Q — ^^:: — m Fishery Bulletin ■^'virES o* '^ JUN 1 1 1979 A Woods Hole, Vol. 77, No. 1 / JanuaryTSTS RICHARDSON, SALLY L., and WAYNE A, LAROCHE. Development and occur- rence of larvae and juveniles of the rockfishes Se6astes crameri,Sebastes pinniger, and Sebastes helvomaculatus (family Scorpaenidae) off Oregon 1 LEATHERWOOD, STEPHEN. Aerial survey of the bottlenosed dolphin, Tursiops truncatus, and the West Indian manatee, Trichechus manatus, in the Indian and Banana Rivers, Florida 47 MORGAN, STEVEN G., and ANTHONY J. PROVENZANO, JR. Development of pelagic larvae and postlarva of Squilla empusa (Crustacea, Stomatopoda), with an assessment of larval characters within the Squillidae 61 COHEN, DANIEL M., and JOSEPH L. RUSSO. Variation in the fourbeard rockling, Enchelyopus cimbrius, a North Atlantic gadid fish, with comments on the genera of rocklings 91 SUMIDA, B. Y., E. H. AHLSTROM, and H. G. MOSER. Early development of seven flatfishes of the eastern North Pacific with heavily pigmented larvae (Pisces, Pleuronectiformes) 105 GREENBLATT, PAUL R. Associations of tuna with flotsam in the eastern tropical Pacific 147 HAYNES, EVAN. Description of larvae of the northern shrimp, Panda/as borealis, reared in situ in Kachemak Bay, Alaska 157 TRICAS, TIMOTHY C. Relationships of the blue shark, Prionace glauca, and its prey species near Santa Catalina Island, California 175 OMORI, MAKOTO, and DAVID GLUCK. Life history and vertical migration of the pelagic shrimp Sergestes similis off the southern California coast 183 NEVES, RICHARD J., and LINDA DEPRES. The oceanic migration of American shad, Alosa sapidissima, along the Atlantic coast 199 KENDALL, ARTHUR W., JR., and LIONEL A. WALFORD. Sources and distribu- tion of bluefish, Pomatomus saltatrix, larvae and juveniles off the east coast of the United States 213 WAHLE, ROY J., REINO O. KOSKI, and ROBERT Z. SMITH. Contribution of 1960-63 brood hatchery-reared sockeye salmon, Oncorhynchus nerka, to the Co- lumbia River commercial fishery 229 MEYER, THOMAS L., RICHARD A. COOPER, and RICHARD W. LANGTON. Relative abundance, behavior, and food habits of the American sand lance, Ammo- dytes americanus, from the Gulf of Maine 243 (Continued on next page) Rpaf.tlp Washincrt.nn U.S. DEPARTMENT OF COMMERCE Juanita M. Kreps, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Richard A. Frank, Administrator Terry L. Leitzell, Assistant Administrator for Fisheries NATIONAL MARINE FISHERIES SERVICE Fishery Bulletin The Fishery Bulletin carries original research reports and technical notes on investigations in fishery science, engineering, and economics. The Bulletin of the United States Fish Conunission was begun in 1881; it became the Bulletin of the Bureau of Fisheries in 1904 and the Fishery Bulletin of the Fish and Wildlife Service in 1941. Separates were issued as documents through volume 46; the last document was No. 1103. Beginning with volume 47 in 1931 and continuing through volume 62 in 1963, each separate appeared as a numbered bulletin. A new system began in 1963 with volume 63 in which papers are bound together in a single issue of the bulletin instead of being issued individually. Beginning with volume 70. number 1. January 1972, the Fishery Bulletin became a periodical, issued quarterly In this form, it is available by subscription ftxjm the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. It is also available free in limited numbers to libraries, research institutions. State and Federal agencies, and in exchange for other scientific publications. EDITOR Dr. Jay C. Quast Scientific Editor, Fishery Bulletin Northwest and Ala.ska Fisheries Center Auke Bay Laboratory National Marine Fisheries Service, NOAA P.O. Bo.\ 155. Auke Bay. AK 99821 Editorial Committee Dr Klhert H Ahlstrom Dr. Merton C. Ingham National Marine Fisheries Service National Marine Fisheries Service Dr. Bruce B. Collette Dr. Reuben Lasker National Marine F'isheries Service National Marine Fisheries Service Dr. Edward D. Houde Dr. Jerome J. Pella University of Miami National Marine Fisheries Service Dr. Sally L. Richardson Gulf Coast Research Laboratory Kiyoshi G. Fukano, Managing Editor The Fishery Bulletin (USPS 090-870) is published quarterly by Scientific Publications Office. National Manne Fistieries Service. NOAA. Room 450. 1107 NE 45tti Street, Seattle, WA 98105 Controlled circulation paid to Finance Department. USPS. Wastiington, DC 20260, Afthougti tfie contents tiave been copyrighted and may be repfinled entirely, reference to source is appreciated. The Secretary of Commerce has determined that the publication of this penodical is necessary in the transaction of the public business required by law of this Department Use of funds for printing of this periodical has been approved by the Director of the Office of f\i1anagement and Budget through 31 March 1982. Fishery Bulletin CONTENTS Vol. 77, No. 1 January 1979 RICHARDSON, SALLY L., and WAYNE A. LAROCHE. Development and occur- rence of larvae and juveniles of the rockfishes Se6as (O >.2 F . n O CD S "^ O (o ■Q CD E -5 £ E - ___ c at "> ^ o "> ™ o Q) CD i: -ill C 0) ?r *= O E w CD 0) X -; 2 S aleulianus S alutus S atrovirens S aunculatus S aurora S babcocki S borealis S brevispinis S carnatus S caunnus S chlorostictus S chrysomelas S ciliatus S constellatus S cortezi S cramen S dalli S diploproa S elongatus S emphaeus S ensfter S entomelas S eos S exsul S flavidus S gilli S goodei S helvomacuiatus S hopktnsi S lord am S lentiginosus S levis S macdonaldi S maliger S melanops S melanostomu . S miniatus S. mystinus S nebulosus S nigrocmctus S notius S ovalis S paucispinis S peduncularis S philtipsi S pinniger S polyspinis S pronger S rasfrelliger S reedi S rosaceus S rosenblatti S rubernmus S rubnvinctus S rufi nanus S rufus S saxicola S semicinctus S serranoides S sernceps S simulator S sinensis S spinorbis S umbrosus S variegatus S. vanspinis S wilsoni S zacentrus S new sp (Lea and Fitch) (P-1 L- L' L- P- P* 'Described as S rubnvinctus. but northern occurrence indicates it must be S babcocki ^Described as S rhodochloris ^These descriptions ot S rubnvinctus must be S babcocki due to the northern occurrence of specimens. RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Longest dorsal fin spine = distance from base to = distance from base to = distance from base to tip Longest dorsal fin ray = tip. Longest anal fin spine tip. All body lengths given refer to standard length unless noted otherwise. Developmental Terminology Terminology for development of Sebastes spp. used in this paper is as follows: Preflexion larva = prior to notochord flexion. Flexion larva = undergoing notochord flexion from time urostyle begins to slant upward until urostyle is in final upturned position and caudal fin is formed. Postflexion larva = from completion of noto- chord flexion (urostyle may still extend beyond the base of the caudal fin) to onset of transformation of 13th dorsal spine and 3d anal spine from soft ray to spine, and to the associated onset of development of juvenile pigment pattern (usually addition of pigment to the dorsum). Transforming larva = from onset to completion of transformation of 13th dorsal spine and 3d anal spine from soft ray to fully developed spine. Also from the onset of development of juvenile pigment pattern to development of distinctive juvenile pigmentation, often in the form of melanistic sad- dles over the dorsum. Pelagic juvenile = from completion of formation of 13th dorsal and 3d anal spine (and thus attain- ment of adult complement of actual fin spines and rays) and development of juvenile pigmentation until no longer captured pelagically. Benthic juvenile = from time of first capture on bottom and usual associated decrease in intensity of melanistic pigmentation to attainment of sex- ual maturitv. Spination (Figure 1, Table 2) Difficulties arise in naming all the spines found in the head region of larvae and juveniles of Sebastes because not all are found in adults. Further complications arise because the names traditionally used for a number of the head spines do not reflect the bone from which the spine origi- nates. For these reasons we include a composite diagram of spines which may occur during the larval and juvenile periods. The terminology is a combination and modification of that used by Phil- lips (1957), Chen ( 1971), Moser (1972), and Moser and Ahlstrom (1978). Most names used in this paper are the same as those used for adult rockfishes to avoid confusion, even though the bones from which the spines originate are not in- dicated by the name. Exceptions are as follows. The two spines found on the opercular margin are here called the subopercular and the interopercu- lar according to the bones from which they origi- nate. The superior posttemporal (supracleithral of adults), inferior posttemporal (not found in adults), and supracleithral (cleithral of adults) are so-called because of their origin. This is done to avoid confusion with a spine present on the poste- rior margin of the cleithrum, which is here called the cleithral spine. Use of the term infraorbital INFERIOR INFRAORBITAL SERIES. 1ST SUPERIOR INFRAORBITAL SERIES, 1ST SUPERIOR INFRAORBITAL SERIES, 2ND INFERIOR INFRAORBITAL SERIES. 2ND --' INFERIOR INFRAORBITAL SERIES, 3RD -'" SUPERIOR INFRAORBITAL SERIES, 3RD SUPERIOR INFRAORBITAL SERIES, 4 TH ANTERIOR PREOPERCULAR SERIES, I ST- 3RD POSTERIOR PREOPERCULAR SERIES, IST-5TH INTEROPERCULAR SUBOPERCULAR INFERIOR OPERCULAR SUPERIOR OPERCULAR NASAL PREOCULAR SUPRAOCULAR F'jST'XULAR Ip' TrMPANIC PTEROTIC PARIETAL NUCHAL r.FERIOR POSTTEMPORAL -yjPERIOR POSTTEMPORAL SUPRACLEITHRAL Figure l . — Composite diagram of spines present in the head region of larval and juvenile Sebastes species including names used in this paper. Refer to Table 2 for correspondmg names used for adults and bones from which spines originate. FISHERY BULLETIN VOL .NO 1 Table 2. — Names of head region spines of larval and juvenile Sebastes spp. used in this paper with corresponding names used for adults and bones from which the spines originate. Spines listed in the first column are shown in Figure 1 clockwise beginning with the nasal. Bone from which Name used in this paper Name used in adults^ spine(s) originates^ Nasal Nasal Nasal Preocular Preocular Prefrontal Supraocular Supraocular Frontal Postocular Postocular Frontal Coronal Coronal Frontal Tympanic Tympanic Frontal Rerotic Pterotic Pterotic Panetal Panetal Parietal Nuchal Nuchal Parietal Interior postlemporal — Postlemporal Superior postlemporal Supracleithral Postlemporal Supracleithral Cleithral Supracleithrum Cleithral — Cleithnjm Superior opercular Opercular Opercle Inferior opercular Opercular Opercle Subopercuiar Gill cover spine Subopercle Interopercuiar Gill cover spine Interopercle Posterior preopercular senes. lst-5th Preopercular Preopercle Antenor preopercular series. 1sl-3d — Preopercle Superior infraorbital senes, 4th — Infraorbilal 3 (2d suborbital) Superior infraorbital senes — Infraorbital 2 fist suborbital) Inferior infraorbital series, 3d — Infraorbital l (preorbital) Inferior infraorbital series, 2d Lachrymal projection (suborbital spine) Infraorbital 1 (preorbital) Superior infraorbital series, 2d — Infraorbital 1 (preorbital) Superior infraorbital series. 1st — Infraorbital 1 (preorbital) Inferior infraorbital series, isl Lachrymal projection (suborbial spine) Infraorbital 1 (preorbital) 'After Phillips (1957) and Chen (1971) ■'Afler Malsubara (1943) and Weitzman (1962) follows Weitzman (1962 Poss.* as recommendeii by SEBASTES CRAMERl (JORDAN) (Figures 2, 3, 4) Literature. — Pigment patterns of preextrusion larvae of S. crameri were described by Westrheim et al.," including one figure, and Westrheim (19751. Preextrusion larvae (mean total length = 5.7 mm) have a rowof 10 to 23 melanophores(45'7f of 60 larvae had <16 melanophores) along the ventral body midline which stops short of the anus by four myomeres. Melanophore(s) are also usu- ally present on the ventral finfold in the hypural region. The gut is pigmented. No pigment occurs on the head, nape, or dorsal body midline, how- ever. Westrheim ( 1975) reported that S. crameri larvae, along with several other species, reared for several days develop pigment spots on the head, nape, and or lower jaw. *S. G. Poss, Ph.D. Candidate, Department of Zoolog>', Univer- sity of Michigan, Ann Arbor, Ml 48109. pers. commun. .Julv 1977. 'Westrheim, S. J., W. R. Harling, and D. Davenport. 1968, Preliminary report on the maturity, spawning season and larval identification of rockfishes i.Sebastotles ) collected off British Columbia in 1967. Fish. Res. Board Can., Manuscr Rep. 9.51.23 p. Identification (Table 3, Appendix Tables 2-6l. — Eighty-one specimens of S. crameri, ranging from 8.0 to 130.5 mm, were identified. Juveniles were identified using the following combination of characters recorded from specimens in our collec- tions: Gill rakers = 30-34 Lateral line pores = 43-50 Pectoral fin rays = 18-20, usually 19 Anal fin soft rays = 7 Dorsal fin soft rays = 13-15 Supraocular spine = present Interorbital space = flat to convex. No other species on our list of potential species agrees with all these characters. In addition, the characteristic pigment banding of adults was ob- vious on larger juveniles. Larvae and juveniles were relatively abundant in our collections and adults are known to be abundant in terms of biomass in trawl catches off the Oregon coast (Demory et al. 1976; Niska 1976). The develop- mental series was linked together primarily on the basis of pigmentation and also body shape and time of occurrence. Identification of most of the smaller specimens was further substantiated by meristics, particularly the constancy in nurn lor of anal and pectoral fin rays (Table 3). RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES 9.0 mm 12.6 mm 14.7 mm FICI RE 2.— Planktonic larvae (9.0, 12.6, 14.7 mml of Si>6as/(?,s crameri. FISHERY Bl'LLETIN VOL 77. NO '). •'' 19.0 mm 3.<^ , ^'¥i^>:J^. '^-/ r %-':^«^< 5c^- t-' ^^-"f^ ;i^(' 22.7 mm 31.8 mm FICL'RK 3.— Transforming specimen 1 19.0 mmi and pelagic juveniles (22.7, 31.8 mmi t,{ Sebastes cr, RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES V> 'X>\ 56.9 mm ..r^'^^^s^^s^s 78.8 mm Figure 4. — Pelagic juvenile (56.9 mm) and benthic juvenile (78.8 mm) oC Sebastes crameri. Distinguishing Features. — Characters useful to distinguish the smallest i(ientified larvae (8.0 mm) are the heavily pigmented pectoral and pel- vic fins, the presence of a heavy nape pigment patch from which some melanophores extend down and over the gut externally on the body wall, the absence of dorsal midline pigment other than at the nape, the presence of ventral midline pig- ment as =11 distinct melanophores of which the anterior ones are embedded and only the posteri- ormost ones remain on the ventral body surface, and pigment at the tip of the lower jaw. The pres- ence of pigment on the first dorsal fin in larvae as small as 11 mm is also a useful character. Meris- tics, presence of a supraocular spine, flat to convex shape of the interorbital space, heavily pigmented FISHERY BULLETIN: VOL. 77. NO. 1 Table 3. — Meristics from larvae and juveniles ofSebastes crameri off Oregon, based on unstained specimens. Specimens above dashed line are undergoing notochord flexion. All specimens had 8 superior and 7 inferior principal caudal fin rays and 7 branchiostcgal rays on each side. Standard length (mm) Dorsal fin spines and rays Anal fin spines and rays Pectoral fin rays Pelvic f spines and Left n rays Right 3111 rakers first arch) Lateral line pores Diagonal scale Left Right Left Right Lett Right rows B.O (') (') — 19 (') (') _ 8.0 (') (') 19 19 i') P) — — — — — 9.0 III + IM3-14 P.7 19 19 M') l.C) _ 9.0 P. 14 P.7 19 19 I.C) 1,0 _ — — — 9.3 P. 14 P.7 19 19 l.C) 1,0 - — — — — 10,6 VI + IM3 P,7 19 19 1.5 1,5 S 10.6 VlllfP.14 ll',7 19 19 1,5 1.5 _ _ _ — — 10.7 IX + I'.13 IP, 7 — 19 1,5 1.5 — 12.2 X + 11.14 IIP,7 19 19 1,5 1.5 _ 19+ 8=27 _ — _ 12.6 XUIM3 IIP.7 19 19 1,5 1.5 — = 19+ 8=27 _ _ _ 12.8 Xl»|i.l4 IIP.7 19 19 1,5 1.5 — — — _ 13.6 XIIIM3 IIP.7 19 19 1,5 1.5 _ -18+ 8=26 — — _ 13.8 XIIIM4 IIP,7 19 20 1.5 1.5 _ -20+ 8=28 — _ _ 14.4 XIIP.14 IIP,7 19 19 1,5 1.5 — -20+ 8=28 _ — _ 14.7 XIIP.14 IIP.7 20 19 1,5 1.5 _ 21+ 9 = 30 _ _ _ 15.4 XIIP.14 IIP.7 18 18 1,5 1.5 — — _ _ _ '16.0 XIIP.14 IIP.7 19 19 1,5 1.5 — 21+ 8=29 _ _ _ '16.3 XIIP,14 IIP.7 19 19 1,5 1.5 — 22+ 8=30 — _ _ '17.3 XIIIM3 IIP.7 19 19 1.5 1.5 — 21+ 9=30 _ _ _ '17.4 XIIIJ.13 IIP.7 19 19 1,5 1.5 _ 22+ 9=31 _ — — '18.2 Xlll^,14 IIP.7 19 19 1.5 1.5 _ 20+ 9=29 _ _ _ '18.4 XIIP,13 IIP,7 20 19 1,5 1,5 — 22+ 9=31 — — — '18.6 XIIIM4 IIP.7 20 20 1,5 1.5 _ 22+ 8=30 _ _ _ '19.0 XIII-M4 IIP.7 19 20 1,5 1.5 _ 22+10 = 32 _ — — '20.0 XIIP.14 IIP,7 19 19 1.5 1,5 21^ 9- = 30 22+ 9=31 _ _ _ '20.3 XIIIJ.14 IIP.7 19 19 1,5 1,5 22 + 9 = =31 22+ 9 = 31 — — — *21.0 XIIP.14 IIP,7 19 19 1.5 1.5 22 + 9- =31 21+ 9=30 _ _ _ 522.7 XIII.13 III.7 20 20 1.5 1.5 22 + 9 =31 22+ 9 = 31 _ 523.5 XIII. 13 111,7 19 19 1.5 1.5 23 + 9 =32 22+10=32 _ =24.2 XIII.14 111,7 19 19 1.5 1.5 23 + 9 = 32 22+ 9=31 _ — — 525.6 XIII.15 III.7 19 20 1.5 1.5 22 + 9 = 31 23+ 9=32 _ _ _ 528.6 XIII.14 111,7 19 19 1.5 1.5 22 + 9 =31 23 + 10 = 33 — =30.0 XIII.13 III.7 19 19 1.5 1.5 22 + 9 =31 23+ 9=32 •48 -47 _ 531.8 Xlil.l3 111,7 19 19 1.5 1.5 23 + 10 = =33 22+10=32 46 _ _ 535.7 XIII.14 III.7 19 19 1.5 1.5 23- 9 = 32 23+ 9 = 32 45 -43 — 538.2 XIII.14 111,7 19 19 1.5 1.5 23 + 10 =33 23+ 9=32 — — _ 556.9 XIII.14 III.7 19 19 1,5 1.5 22 + 9 =31 22+ 9 = 31 45 46 _ 546.8 XIII.13 III.7 19 19 1,5 1.5 24 + 9 =33 23+ 9=32 -48 — — 549.2 XIII.14 111,7 19 19 1.5 1.5 23 + 10 =33 24 + 10=34 ^43 =46 _ 558.9 XIII.14 III.7 19 19 1.5 1.5 22+ 9 =31 22+ 9=31 45 45 — 563.0 XIII.14 III.7 19 19 1.5 1.5 23 + 9 =32 23+ 9=32 45 46 _ 563.2 XIII.13 III.7 19 19 1.5 1.5 22 + 9 = =31 23+ 9=32 JO 46 _ 565.0 XIII.14 111.7 19 20 1.5 1.5 24 + 9 = 33 24+ 9=33 49 50 _ 567.6 XIII.14 111,7 19 19 1.5 1.5 22 + 10 = 32 23 + 10=33 47 48 — 578.8 XIII, 14 III.7 19 19 1,5 1,5 22- 9- -31 22- 9-31 48 44 _ '86.1 XIII.13 111,7 19 18 1.5 1,5 23 + 9 =32 23+ 9=32 46 46 _ 591.8 Xlll,14 III.7 19 19 1.5 1,5 22 + 10 = 32 23-10=33 47 49 -53 594.4 XIII.14 III.7 19 19 1.5 1,5 22 + 8 =30 22- 9=31 49 47 -59 594.7 XIII.14 111,7 19 20 15 1,5 23 + 10 =33 23- 9=32 45 45 — 596.2 XIII.13 III.7 19 18 1.5 1,5 22 + 9 =31 22+ 9=31 47 45 •55 5105 6 XIII.13 111,7 19 19 1.5 1.5 22 + 9 = -31 22+ 9 31 47 47 -51 5125.7 XIII.14 111,7 19 19 1.5 1.5 23- 9 = -32 23+10-33 45 44 -59 5130.5 XIII.13 111,7 20 2" 1.5 l.."^ 23 + 10 = =33 23+ 9=32 46 47 -60 forming ^Nol formed ^Posteriormost dorsal or anal spine appears as a soft ray ^Transforming. ^Pelagic juvenile 5Ben1nic juvenile pectoral and pelvic fins, and pigment banding pat- tern on the body serve to distinguish juveniles. General Development. — The smallest specimens (8.0-9.0 mm) of S. craryieri in the series are under- fi^o'.ig the final stages of notochord flexion, which i.'^ completed by the time larvae are 10 mm. Trans- formation from postflexion larvae to pelagic juveniles is rather gradual beginning when larvae are about 16 mm. It is charactorized by addition ot pigment beneath the second d^rs.'l fin along witli initiation of structural change of ihe "prespines" in the dorsal and anal fins. Tr.msformation is complete in 22 mm specimens and the juvenile pigment pattern is obvious. Transition from pelagic to bentbic habitat probably occurs when fish are 40 to 60 riim. The largest 1 elagif uvenile. captured in a neuston net. was 56.9 mm and the 1' RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES smallest juvenile taken in a bottom trawl was 46.8 mm. Morphology (Tables 4, 5). — Measurements of var- ious body parts were made on 53 selected speci- mens of S. crameri, ranging from 8.0 to 130.5 mm long, to examine developmental morphology. Rel- ative body depth at the pectoral fin base and at the anus increases somewhat, 32 to 34% SL and 24 to 28'7f SL, respectively, during development from flexion larvae to benthic juveniles. A more marked change occurs in snout to anus distance which increases from 54 to 65'7f SL. The distance from the snout to the pelvic fin base increases slightly. Head length decreases somewhat during de- velopment from 39 to 369c SL, while major de- creases occur in eye diameter (40-33% HL), upper jaw length (56-41% HL), and interorbital distance (36-23% HL). Snout length first increases slightly and then decreases with respect to head length. The length of the angle gill raker increases from 9 to 16% HL. Fin Development (Tables 3, 4, 5). — Pectoral fins are formed in 8 mm larvae of S. crameri and the adult complement of 18 to 20 (usually 19) fin rays (or ray elements) are countable in 9 mm speci- mens. The fins become more elongate with de- velopment, increasing from 17% SL in flexion lar- vae to a maximum of 32% SL in pelagic juveniles. Depth of the pectoral fin base decreases from 13 to 10% SL. Pelvic fin buds are present on 8 mm lai'vae and the forming spines and rays (1,5) can be counted in 9 mm larvae although they are not fully developed until the larvae reach about 10 mm. Length of the pelvic fins increased from 7 to 21% SL during the larval and juvenile periods. Length of the pelvic spine, which is less than the longest ray, increases from 5%' SL in flexion larvae to 19% during trans- formation, and then decreases to an average of 13% in benthic juveniles. In 8.0 mm larvae the adult complement of 8 -i- 7 principal caudal rays can be counted although notochord flexion does not appear to be complete until larvae are >9.3 mm. Counts of superior and inferior secondary caudal rays made on one stained juvenile, 38.2 mm, were 12 and 13, respec- tively. Bases of some dorsal and anal fin rays and spines are visible on 8 mm larvae. Development of the second dorsal and anal soft rays occurs simul- taneously with the central rays forming first and the posteriormost rays last. Developing soft ray elements are visible and adult complements can be counted on 9 mm larvae although rays do not appear fully formed until larvae are >10 mm. Dorsal spines begin to form slightly after initia- tion of soft ray formation at =9 mm. The third, fourth, and fifth dorsal spines develop first. The 12th spine is not formed until larvae are >13 mm long. The second anal spine is formed at 10.6 mm and the first is formed by 12 mm. The transition of dorsal and anal fin "prespines" to spines is com- plete at around 22 mm. The longest dorsal spine increases from 22 to 45% HL during the pelvic phase, and decreases to 37% in benthic juveniles. The longestdorsal ray increases from 26 to 41-43% HL during development. The longest anal spine increases from 16 to 37 or 38% HL. Spination (Tables 4, 6). — Spines visible on the left side of the head of an 8.0 mm larva of S. crameri consist of the parietal; the second, third, and fourth preopercular spines of the posterior series; the first, second, and third preopercular spines of the anterior series; the postocular; and the pterot- ic. Another more developed 8.0 mm specimen has a developing nuchal spine bump; the inferior post- temporal; the first spine of the inferior infraorbital series, and the first spine on the superior infraor- bital series. The parietal spine is relatively short, averaging 6.5 to 6.6% HL in larvae and decreasing to 3.0% HL in pelagic juveniles. The nuchal spine in- creases in length from 1% HL in flexion larvae to 4% in postflexion and transforming specimens then decreases to 3% in pelagic juveniles. Parietal and nuchal spines begin to fuse near their bases at 10.7 mm, gradually fusing towards the tips until in specimens >38 mm the parietal tip is no longer visible. In benthic juveniles the nuchal and parietal spines are fused and their relative lengths are =2% HL; however, increased pigment and musculature allowed measurement only from tip to body junction. The parietal spine and ridge are not serrated in larvae <9 mm. Serrations first appear at the center of the parietal ridge at 9 mm and persist until =39 mm. The posterior series of preopercular spines are among the most prominent in the larvae. The first through fifth spines of the series are present in larvae >10 mm. The third spine of the series is the largest, averaging 17 or 18% HL in larvae and then decreasing to 7% HL in benthic juveniles. Spines in the posterior preopercular series never 11 FISHERY BULLETIN: VOL. 77. NO. 1 Table 4.— Body proportions of larvae and juventies of Sebastes cramen.S. pinniger. andS. helvomaculatus . Values given are percent standard length iSL) or head length (HLl including mean, standard deviation, and range in parentheses. (Number of specimens measured may be derived from Tables 5, 8. and 11.) Item Sebastes cramerl Sebastes pinniger Sebastes helvomaculatus Body depth at pectoral tin baseiSL: Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Body depth at anusiSL: Flexion Postflexion Transforming Pelagic Juvenile Benlhic Juvenile Snouf fo anus length SL: Flexion Postflexion Transforming Pelagic Juvenile Bentfiic Juvenile Snout to pelvic fin ongin:SL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Head lenglh'SL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Eye diameterlHL: Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Upper law length HL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Snout lengthHL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Interorbital distance HL- Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile 4r7g/e gill raker length HL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Longest dorsal spine length^ HL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Longest dorsal ray length^ HL. Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Longest anal spine length^ HL: Flexion Postflexion Transforming 31.8±2.05(29.0-33.8) 31. 7 ±1,26(30 3- 34 9) 32.4±1 74(29 5-35 6) 32.7±1 89(30,3-37.4) 34.4±1,96( 30.1-36.5) 23.6^0 67(22 6-24 4) 24 9±1 19(22 6-26 5) 26.7±1 34(24 7-29 4) 26.8 ±1 15(26 2-29.2) 27.7±1 56(25 1-30 7) 54.0±1 28(52 5-559) 60.5±325(55 1-65 1) 61 .a±3 26(54 3-65 0) 61 .6 ±2 63(57 9-64 3) 65.0:!: 1.81(61. 5- 68 7) 37.6±1 56(35.0-38.9) 40 8±2 02(38 1-44 3) 39 8±3 49(34 1-46.5) 38.9±3 23(34.0-44 5) 40.5 ±1.86(37.3-43.1) 39.0±1 55(37 5-41 1) 38.9 ±1 90(36 8-43 4) 36 6 ±2 43(32 8-38 7) 35.8±1 82(32 3-38 3) 36.4 ±2 75(31 8-39 9) 40.2±1 82(37 8-42 9) 38.2± 1.87(33 9-40 0) 36 9±2 47(33 3-42 1) 30 4 ±2 60(26 6-35 0) 31 .6±2 05(28 9-35 6) 46.5±4.35(40.5-50.0) 43 6±2 45(40 0-46 3) 438±5 55(34 2-50 9) 41 3±4 06(33 9-47 5) 41 2±2 44(37 8-45 6) 29.1 ±1 38(27 0-30 7) 30 0±1 65(26 1-31 7) 31 2±2 69(27 0-35 6) 28 2±2 97(24 6-32 1) 26.3±2.43(22 4-31 2) 35.6 ±1.95(32 4-37 1) 33.0±1 94(29 3-36 0) 31 2±339(259-368) 25 9±2 48(23 0-30 0) 21.6±2 18(18 0-26.8) 8.6±0.00(8.6) 11 4±1 77(8 6-14 4) 13 1 ±1 13(11 1-15 1) 139±082(13 3-15 1) 158tl 06(13 7-174) 21 6±2. 26(19 4-24 1) 34.3±7 13(26 2-45 1) 44 7± 1.55(42 0-46 2) 36.9 ±4 32(31 7-44 3) 26.2±6.96(14 6-33 3) 41.4±232(39 3-43 9) 42.0±2 97(38 1-46 7) 43 1*4 74(37 6-48.1) 15 6±3.16(9 6-18.5) 28.1 ±3 46(23.0-32 0) 40.3±0.92(39.7-41 0) 38 1 ±2 51(33 7-42 0) 35 9±1 36(33 3-38 3) 33.0 ±1.88(29.8-37 0) 34.9±2 15(32 7-37.0) 27 6 ±0 92(26 9-28 2) 285-1 92(24 7-30 6) 27 6»1 63(24 8-30 9) 26.0±1. 11(239-28.0) 29 8±3 68(27 3-34 0) 58 8±1 63(57 7-60 0) 59 6 ±3 42(51 7-62 6) 606 • 1 84(58 1-63 1) 61 4. '3 50(56 0-67 4) 64 2±3 27(60.6-67 0) 41 1 ±3 61(38 5-43 6) 40 7±3 03(34 7-44 9) 41 9*2 74(38 7-46 2) 39 9±3 83(32 9-45-5) 42.7±2.86(41.0-460) 43 ±0.92(42.3-43 6) 42 4 • 2 58(38 2-47 7) 40 5±1 39(38 0-42 6) 37 5±2 52(33.3-42 1) 366±0 51(360-37 0) 37 3 1 27(36.4-38 2) 39 3 1 89(37 5-41 3) 37 5 1 35(34 2-38 7) 34 2 2 77(30 8-42 3) 26 8 -3 22(24 0-30 3) 47 8 -0 99(47 1-46 5) 46 1 3 73(41 2-524) 42 1 ►3.64(35.6-47.0) 41 3- 3 14(34.6-47 4) 44 9 ±2 15(42 7-47 0) 26 9 ►0 28(26 7-27 1) 28 7 -3 45(23.8-34 8) 30 2 ±3 31(25 8-36 5) 27 3 *3 68(21 7-32 5) 28 8 ±0 72(28 0-29 4) 37 3 •127(36 4-38 2) 342 ±2 26(30 4-38 2) 30 ± 1 82(26 3-32 3) 24 4 •3 31(19 5-30 8) 198 •137(183-210) 106 ±1 42(8.3-123) 130 •0 72(11 5-14 5) 14 1 ±1 21(11 7-16 5) 149 ±1 10(138-160) 20 1 ±6 05(13 0-28 6) 32 4 •5 49(23 6-40 6) 38 0±3 79(33.1-46 2) 35 6±4 74(32 0-41 0) 31 5 ±4 26(23.8-38 0) 38 5± 3 60(30 8-42 9) 41 6 ±3 46(35 4-48 7) 42 6±3 83(40 0-47 0) 18 7 ±2 52(14 6-21 3) 28 5 ±5.65(20.0-38 6) 33 3 ±1.44(32.5-35.0) 33 4 ±0 46(33 0-33 9) 32 6±1 79(30 6-35 8) 31 2 ±1.58(28 4-32 9) 33 4 ±1.63(32-3-34.6) 20 7±0.61(20.0-21 2) 24 5 ±2.56(21 6-26 3) 24 7±1 22(23.1-26.9) 23 2±1 24(21 2-25.0) 25 4 ±2 33(23 7-27 0) 56 1 ±1.28(55 0-57 5) 59 1 ±0 50(58 6-59 6) 61 7±1 86(59 2-64 5) 62 8 ±2 46(59 8-66 0) 638*1 06(630-645) 40 5±1 27(39 0-41 2) 40 9±0 45(40 4-41 3) 42 8=3 13(38 0-47 3) 42 8±3 16(39 3-48 2) 40 ±0 92(39.4-40.7) 41.4±1.27(40 0-42.5) 42.0±2 03(40 4-44.3) 40 8±1 92(36 4-43 0) 40 1±1 48(37 5-41 9) 37 6 ±0 57(37 2-38 0) 38 8±1 63(29 4-31 2) 36 3±0.36(35 9-36 6) 35 5 ±2 38(32 0-38 8) 33 6 : 1 76(30 8-36 9) 31 6±5 30(27 8-35 3) 45 ±3.29(4 1.2-46.9) 44 0±3 00(41 0-47 0) 45 7 ±4 23(39 7-53 1) 45 1 ±2 63(40 2-47 6) 52 1 ±0 78(51 5-52.6) 32 3±2 20(30 0-34 4) 330±1 18(31 7-34 1) 32 4±3 72(25 0-37 9) 31 7 ±2.49(26 7-34 1) 26 7±0.42(26.4-27 0) 30 6±1 04(29 4-31 2) 31 4 ±0 55(30 8-31 8) 27 0±2 89(23 3-30 6) 21 5±3 83(13 3-25 6) 146±247(129-164) 134±095(12.3-14 1) 15 1±1 46(12 9-180) 14 2±1 90(12 7-15 7) 10 6±0 50(10 3-1 10) 19 0±0 64(18 6-19 5) 29 2±6 08(22 4-37 5) 30 9±2 93(28 0-35 7) 37 ±4.88(33 6-40 5) 22 8±7 39(1 5 9-30 6) 26 4 ±5 14(20 5-29 5) 36 1 ±3 08(32 5-41 7) 35 1 ±2 53(32 0-38 1) 42 8 ±3 89(40 0-45 5) 160±1 91(146-173) 27 3 ±4 46(22.4-36 1) 12 RICHARDSON and LAROCHE, DEVELOPMENT AND OCCURRENCE OF ROCKHSHES Table 4.— Continued. Item Sebastes cramen Sebastes pinniger Sebastes helvomaculatus Pelagic Juvenile Benthic Juvenile Pectoral fin length SL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Pectoral tin base depth SL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Pelvic fin length 'SL: Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Pelvic spine length SL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Parietal spine lengthHL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile Nuchal spine length HL Flexion Postflexion Transforming Pelagic Juvenile Benlhic Juvenile Preopercular spine lengthiHL Flexion Postflexion Transforming Pelagic Juvenile Benthic Juvenile 37 8-4 36(31,2-43 5) 36 5*4 34(30 6-44 31 17 1 ±1 52(150-189) 21 1 12 26(17 0-23 5) 27 1^1,54(24 7-29 5) 32 1-1 73(30 2-35 3) 29 5±3 61(25 0-38 9) 126-1 27(108-138) 11 IrO 39(10 4-11 8) 104±061(95-11 7) 96i051(85-102) 10,2:0 53(8 8-10 9) 7,3:1 81(52-98) 15,3:1 46(12,3-16,9) 20 6:1 01(18.3-22 1) 20 9:0 60(20 1-21 9) 20 7 '0 97(18 5-22 2) 4 7:1 42(3 4-6 2) 11 4:2 20(6 8-14 6) 18 8:1,65(14,5-20 1) 19 0:1 35(16.2-20,7) 13 9:1 34(12,3-17 1) 65:1 01(54-7 4) 6 6:1 06(5 2-8 5) 6 0:1 24(3 7-7 4) 2 9:0 98(1 8-4 2) 1 1 :0 00(1 1) 4 1 :0 73(3 4-5 8) 44:088(3 1-6 0) 3 2:1 03(2 0-5 0) 1 7:0 64(0 7-2 8) 176 13 84(120-205) 170:1 09(15 5-185) 183:1 53(160-19,7) 12 0:2 85(8 6-16 2) 72:2 72(3 Ml 4) 37 4:4 07(30 8-44 0) 34 5:2 50(32 0-37 0) 25 0:2 69(23 1-26 9) 24 7:2 64(20 2-28 5) 27 0:2 42(22 7-31 5) 26 2:1 36(24 0-28 5) 243:1 21(22 9-25 0) 148:092(14 1-154) 12 6:083(11 4-13 6) 107:0 69(9 7-11 5) 9 1:0 64(8 2-10 1) 8 9:0.23(8 6-9 0) 13 8:2 19(12 3-15 4) 172:4 12(10 0-22 8) 22 7:1 59(20,8-25 3) 21 7:1,29(19,4-23 7) 21 3:2,08(19.0-23 0) 5 1:0 00(5 1) 12 1:299(82-150) 19.5:1 38(17 6-21 7) 17 9:2 10(14 5-22 1) 125:0 50(120-130) 24 4:0 35(24,2-24 4) 19 5:7 17(8 8-23 5) 10 2:3 07(3 9-12 9) 7 1:2.66(5.4-10 2) 4 4:1 63(2 5-6 9) 4 8:1 57(2 3-7 2) 3 1:0 96(1 9-5 4) 1 4:0 64(1 0-2 1) 34 4:2 83(32 4-36 4) 31 8:4 86(25 0-39 0) 23 6:2 09(21 2-29 1) 12 8:3 96(9 1-22 2) 4 8:1 39(4 0-6 4) 32 4:5 70(26 8-38 1) 48 8:4 67(45 5-52 1) 23 6:2 11(21 2-25 0) 24 4-0 57(23 9-25 0) 26 : 1 45(24 3-28 3) 26 6:0 28(26 1-26 9) 27 0:0 85(26 4-27 6) 12 5:0 00(12 5) 11 5:084(11 0-125) 9 9:0 64(9 0-10 8) 90:033(82-9 1) 9 3:0 71(8 8-9 8) 135:1 32(125-150) 155:070(148-162) 193*1 62(167-21 6) 192- 1 36(173-21 4) 22 7 1 99(22 0-23 4) 8 3:0 15(8 2-8.5) 12 3:2 26(10 2-14 7) 176:1 02(158-19 1) 164-1 99(135-189) 14 9-0 71(14 4-154) 27 4:4 19(22 9-31 2) 185:224(159-20 0) 126:239(90-163) 56-331(1 1-9 5) 3 1 :000(3 1) 1 8:0 85(1 2-2 4) 4 3:1 51(2 6-5 0) 4 6:0 78(3 0-4 9) 3 5:1 13(1 7-5 2) 27 4:4 19(22 9-31 2) 31 2 '064(308-31 7) 20 2-3 58(16 2-26 5) 11 8 16 29(2 5-15 9) 1 6:1 34(0 6-2 51 'Usually third or fourth in larvae -Usually midfin ^The second spine. fifth or sixth in juveniles develop strong serrations. Spines in the anterior preopercular series are much shorter than those in the posterior series. The second or middle spine is present only in larvae prior to completion of notochord flexion. <10 mm. Its appearance as a spine changes to a small bump which then fuses with the ridges connecting it to the third preoper- cular spine of the posterior series- The first and third anterior spines are present on larvae through pelagic juveniles of =23 mm and then are no longer visible- The superior and inferior opercular spines and the interopercular spine appear by the time the larvae reach 12 mm, although percursor bumps may be seen as early as 9 mm. These spines persist into the juvenile stage. The subopercular spine is present in juveniles >78 mm. Around the eye, the ridge anterior to the post- ocular spine becomes serrated at 10.6 mm. These serrations disappear at the time of supraocular spine formation, >21 mm. The preocular spme begins to appear in transforming specimens >16 mm and is strongly formed by the time fish are 20 mm. Beneath the eye the second spine of the in- ferior infraorbital series forms in larvae >10 mm. The fourth spine of the superior infraorbital series develops under the posterior third of the eye on larvae >13.6 mm and it persists through the juvenile stage as do the two inferior infraorbital spines. The second and third superior and third inferior infraorbital spines never develop. Tiny serrations appear along a ridge between the first and fourth superior infraorbital spines in speci- mens 14.4 to 38.2 mm. The first spine of the superior infraorbital series disappears in speci- mens >50 mm. The nasal spine develops m larvae of =10 mm and persists in juveniles. 13 FISHERY BULLETIN: VOL. 77. NO I T.'\BLE 5. — Measurements (millimeters I of larvae and juveniles o(Sebasles cramen from waters off Oregon. Specimens above dashed line are undergoing notochord flexion. 55 |f en ■a'St .c O 0) 0) S ctsz S E 2$ ^ £ c (5 _ c 9? £ _ -D Q. 01 h > 01 is Q- c Sue •^ > en ra "* — Q. c a. UO, l«s 25 mm. This spine forms at the anterior edge of a foramen of the cephalic lateral line system. The pterotic spine is present in flexion larvae and disappears in juveniles >50 mm. The supracleithral spine develops in larvae of ~11 mm and the superior posttemporal spine can be seen on specimens >18 mm. These latter three spines per- sist in juveniles, however, the inferior posttem- poral becomes reduced in larger juveniles. A cleithral spine develops dorsal to the pectoral fin base immediately posterior to the opercular mar- gin on juveniles >30 mm. 14 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Scale Formation. — Lateral line pores are visible on transforming specimens >18.2 mm. Develop- ing scales are first visible on unstained specimens =20 mm on the posterodorsal region of the head and anterodorsal region of the trunk above the gut cavity. Scale development proceeds posteriorly with the body being covered by 29 mm. Pigmentation. — Melanistic pigment on 8.0 mm specimens of S. crameri (similar to the 9 mm specimen illustrated) is present on the head over the brain. Melanophores line the inside tip of the lower jaw and may also be present along the an- teroventral margin of the maxillary. In the ab- dominal region interna! melanophores are dense- ly concentrated on the dorsal surface of the gut and more sparsely distributed laterally and ventrally. Additional external melanophores are present on the body wall over the gut cavity. A heavy con- centration of external melanophores and some in- TABLE 6. — Development of spines in the head region o^ Schastcs crameri larvae andjuveniles. Specimens above dashed line are undergoing notochord flexion. + denotes spine present and - denotes spine absent. Standard length (mm) Parietal Nuctial Preopercular (anterior series) Preopercular (posterior series) Opercular 5tti Supenor Interior cular Inter- Sub- oper- oper- Pre- Supra- Post- cular cular ocular ocular ocular 80 + - + 80 + + + 90 -f + + 90 + - + 93 + + - 106 + + + 106 4- -f -f 122 + -t- + 126 + + + 128 + + + 136 + + + 138 + + + 14 4 + + + 14 7 + + + 154 + -1- + -'16 -*- + + M63 + + + ^173 + + -t- '174 + -f + '182 + + + '184 + + + '18 6 + + + '19.0 -f- + -t- '20-0 + -1- + '203 + + + '21.0 -f + ■t- '227 + + + =23-5 + + V) '24-2 + + '25-6 + + - '28.6 + + - '30-0 -t- + - '31.8 + + - '357 -*- + - '382 -*- -f - '56 9 + + - M6.8 + + - ■•49.2 + + - '58 9 + -(- - "63.0 + + _ -63 2 + + - "65 + + _ "67 6 + + - "788 + + _ "86.1 + + - "91 8 + + - "94.4 + + - "947 + + - "96.2 + + _ "1056 + -f - "125 7 ^^ + 5 _ "1305 -i-5 + S - (') V) 'Bump indicates beginning of spine formation. ^Transtorming ^Pelagic )uvenile ^Benthic juvenile ^Parietal and nuchal spines fused ^Spine IS bifid 15 FISHERY BULLETIN: VOL, 77. NO 1 Table 6. —Continued. Infraorbitals Nasal length (mm) Interior Superior Posttemporal <-„p„. 1st 2d 3d 1st 2d 3d 4tfi Coronal Tympanic Pterotic Superior Interior cleithral Cleilhral 8.0 80 90 90 93 106 106 122 126 128 136 138 144 147 154 '160 '163 '17,3 '174 '182 '18 4 '186 '19.0 '20.0 '20,3 '2' J22 7 J23,5 >242 325.6 ^28.6 '30.0 '31 8 '35.7 '382 '56 9 "46.8 M9 2 ■■58 9 '630 ■•632 -65 "67.6 '78 8 "86 1 "91 8 "944 "94 7 "96 2 "105 6 "125.7 "130.5 {') + + + + + + + + + + + + + + + + + + + + + + (') + + + + + + + ternal pigment is present in the nape region al- though the dorsal midline is pigmentless. A few large stellate melanophores extend laterally from the nape to the gut cavity. A series of 10 or 11 distinct melanophores is visible along the ventral midline of the tail, the anterior five of which are embedded in musculature dorsal to the developing anal fin. A few small melanophores may be pres- ent on the notochord tip. The pectoral fins are distinctively and heavily pigmented. A dense con- centration of melanophores occurs on the proximal surface of the fin base but the distal surface is unpigmented. Elongate melanophores line the inner and outer surfaces of the fin blades creating a striated appearance. The developing pelvic fins are also pigmented. As larvae develop, pigment increases on the head over the brain. Melanophores persist along the tip of the lower jaw and the anteroventral margin of the maxillary. Several melanophores develop around the bases of the posttemporal and supracleithral spines in larvae >10.5 mm and on the dorsal part of the operculum anterior to the opercular spines in larvae >13.5 mm. Pigmentation within the gut cavity remains in- tense through larval development and external melanophores remain scattered on the body wall over the gut. In larvae -10.5 mm, as dorsal fin 16 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES spines develop, melanophores are added to the nape patch along the dorsal midline and posteri- orly along the dorsolateral body surface. The large stellate melanophores extending from the nape patch to the gut disappear by 12 mm. A few exter- nal melanophores appear along the anterior mar- gin of the middle of the cleithrum beneath the gill cover in 12 or 13 mm larvae. In the tail region the ventral midline melano- phores gradually become embedded, anterior ones first, and are obscured by overlying musculature by the time larvae are 13 mm long. A melanophore is sometimes present near the tip of the notochord. The pigmentation of the paired fins increases m intensity throughout the larval period, although the di.stal base of the pectoral fin remains unpig- mented. As the pelvic fins develop, melanophores line the rays giving a striated appearance similar to that of the pectoral fins. Melanophores appear on the anterior portion of the spinous dorsal fin by the time larvae are 11 mm long, and the anterior two-thirds of the fin remains rather heavily pigmented throughout larval development. The soft dorsal and anal fins remain unpigmented. One to several internal, vertically elongate melanophores appear at the base of the caudal fin posterior to the hypural elements on most larvae >9 mm long, but the fin base is never completely lined with pigment. During the transformation period, 16 to 21 mm, pelagic juvenile pigmentation begins to develop. On the head, pigment increases around the post- temporal spines and joins with the nape pigment. Internal and external melanophores are added on the dorsal part of the opercle forming a patch which expands ventrally on specimens >19 mm. Scattered melanophores appear along the dorsal surface of the snout and the anterior portion of the upper lip (internal and external) on specimens >18.5 mm long. Pigment increases around the orbit, lining the dorsal, posterior, and ventral margin of the orbit by 19 mm. In the abdominal region, an increase in musculature over the gut cavity obscures the internal gut pigment although scattered external melanophores persist. The nape patch extends anteriorly joining the head pigment, laterally toward the body midline, and posteriorly to the 12th dorsal spine. Two saddles of intensified melanistic pigment begin to develop beneath the first dorsal fin late in the transforma- tion period. An anterior saddle joins the head pig- ment and another saddle located midfin expands ventrolaterally. Melanophores are added dorsally and ventrally along the anterior margin of the cleithrum beneath the gill cover, eventually ap- pearing as a line of pigment. In the tail region, melanophores appear beneath the middle of the second dorsal fin in 16 mm specimens. They ex- pand anteriorly to join the pigment beneath the spinous dorsal, posteriorly over the caudal pedun- cle, and laterally towards the body midline ap- pearing as a saddle by 20 mm. Some melanophores at the base of the second dorsal fin become concen- trated along muscles surrounding the dorsal pterygiophores giving the appearance of vertical lines of pigment by 20 mm. An additional melanophore may appear at the point of articula- tion of each dorsal soft ray 4 through 10 beginning on 18 mm specimens. Pigment is added internally and externally along the lateral midline of the caudal peduncle. On the first dorsal fin pigmenta- tion increases extending posteriorly to the 1 1th or 12th dorsal spine. In pelagic juveniles >22 mm long, small melanophores appear over the surface of the head. Melanophores almost entirely ring the orbit by 31 mm. Pigment increases on the snout and upper and lower jaws. The two pigment saddles beneath the first dorsal fin become more pronounced and extend moi-e ventrolaterally. A third saddle forms beneath the first dorsal fin posterior to the first two in specimens about 22 to 25 mm long. In the tail region, the saddle beneath the second dorsal fin extends to the lateral midline by 24 mm and even- tually reaches the ventral body margin in a 57 mm specimen. The number of melanophores increases on the caudal peduncle until dorsal and lateral pigment are joined forming a fifth pigment saddle in juveniles about 25 mm long. This fifth saddle eventually extends to the ventral body margin as does the saddle beneath the spinous dorsal fin. An increase in the number of melanophores occurs along the lateral midline of the caudal peduncle giving the appearance of a distinguishable, but not heavy, line of pigment. Small melanophores are added between saddles 3 and 4 and 4 and 5, along the myosepta first. The pectoral and pelvic fins remain heavily pigmented, although the amount of pigment on the base of the rayed portion of the pectoral fin decreases. Pigmentation on the spinous dorsal fin decreases in intensity between spines III and V, and between spines VIII and IX, corresponding to areas between the first, second, and third pigment saddles on the body. On speci- mens >38 mm long, pigment on the dorsal fin 17 FISHERY BULLETIN VOL 77. NO. 1 above the third saddle darkens into a distinct black blotch. Melanophores are added to the basal half of the second dorsal fin above the fourth sad- dle, appearing continuous with it on specimens ■29 mm long. Melanophores are also added to the basal half of the anal fin eventually extending from the second anal spine to the posteriormost anal fin ray on all specimens >38 mm. Specimens >36 mm have a melanophore at the point of ar- ticulation of each soft anal fin ray, although these melanophores soon become obscured by muscula- ture and scales. Three to seven small external melanophores are added near the bases of the caudal fin rays forming an indistinct line. Benthic juveniles >60 mm long retain essen- tially the same melanistic pigment pattern as pelagic juveniles except the intensity decreases resulting in a somewhat faded appearance. Addi- tional light scatterings of melanophores appear in the lower jaw and gular region, second dorsal and anal fins, and body in general. Two bars of pigment radiate ventrally from the posteroventral margin of the eye. The basic banding pattern and black blotch at the base of the dorsal fin remain evident in the largest juvenile, 130 mm, examined. This is the same banding pattern apparent in adults, however, the black blotch on the spinous dorsal fin disappears. In life (Moser**) a juvenile (122 mm) is reddish- brown dorsally, with white on the belly and five brownish bars on the bodv. The first four bars "H. G, Moser. Fishery Biologist (Research i. Southwest Fisheries Center. National Marine Fisheries ,Service, NOAA. P.O. Box 271, La Jolla, CA 92038, pers. commun. 1977. extend ventrally to slightly below the lateral line and dorsally onto the dorsal fins as diffuse dark areas. The head is reddish-brown and pale below eye level, with three brownish transverse bars: one at the anterior level of the orbit, one at the posterior level of the orbit, and one between and posterior to the parietal ridges. A large spot is on the opercle dorsally, and the axillary region has a dusky blotch. Except for the dark bars, the first and second dorsal fins are dusky at the base, grad- ing to pale orange or yellowish with Vermillion or deep red at the margin. The basal half of the anal and pelvic fins is whitish and the distal half grades from reddish to dark orange-red at the tips. The outer pelvic ray has a milky white lateral margin. The pectorals and caudal fins are pale orange, the pectorals with dark orange-red tips and the caudal with a faint dusky band on its posterior half Occurrence (Figures .5, 6 1. — Sebastes crameri ranges from Santa Catalina Island off southern California to the Bering Sea (Miller and Lea 1972). Off Oregon, Washington, and British Co- lumbia it is primarily an outer shelf/upper slope species generally occuring in depths of 150 to 300 m (Snytko and Fadeev 1974). Distinct population clumps have been found off the Oregon coast be- tween lat. 44°30' and 45°20' N (Snytko and Fadeev 1974). Most of our collections containing young S. crameri were taken along a transect off Newport (lat. 44°39.1' N) off the central Oregon coast. The smallest larvae and the greatest numbers of lar- vae and pelagicjuveniles were taken at stations 83 and 93 km offshore (water depths 700-1,300 m). The nearest inshore station on this transect at L- • r •r L ^» h Pelagic Juveniles 1 . . ■-■ ^1 ^i ^1 'i V*™""" *'. ; ^*\ Lil* r H : A„^ Benthic Juveniles / -:.. : - "i - \ ^1 V~-— ,.| FlOURE 5. — Number of specimens and location of capture oflarvae and juveniles ofSehnstes crameri ofTOregon ( 1961-75) described in this paper. 18 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES MAR 40 60 eO 100 Stondofd Length (mm) 20 140 Figure 6. — Seasonal occurrence of larvae and juveniles of Sebastes cramen off Oregon. Data from 1961 to 1975 combined. Dashed line separates pelagic and benthic stages. which a larva (15.7 mm) was taken was 28 km (depth 95 m). The farthest offshore occurrence on this transect was a 26 mm pelagicjuvenile 194 km offshore. Benthic juveniles were generally taken nearer to shore than larvae or pelagic juveniles at depths of 55 to 200 m. Most pelagic specimens came from Isaacs-Kidd midwater trawls towed obliquely through the water column. Four speci- mens, 17.7, 24.0, 38.2, and 56.9 mm, were collected in a neuston net in June, 56 to 65 km off Newport. Spawning times reported for S. crameri are November through March off California (Phillips 1964) and primarily February off Oregon, Washington, and British Columbia (Westrheim 1975; Westrheim et al. see footnote 7). However, mature females with ovaries containing embryos have been collected in February, March, ,'\pril. and June (Westrheim et al.,^ see footnote 7; Mar- ling et al.'"). Pelagic specimens in our collections were taken primarily in April, May, and June although two postflexion larvae were taken in August. Larvae under 10 mm were only taken in April and May. No specimens were taken Sep- tember through February. Because of a lack of information on larval growth, parturition time 'Westrheim. S. J.. W R. Harling, D, Davenport, and M. S, Smith. 1968. Preliminary report on maturity, spawning sea- son, and larval identification of rockfishes iSeicstorfcsl collected off British Columbia in 1968- Fish, Res. Board Can.. Manuscr Rep. 1005, 28 p, '"Harlmg.W. R.. M.S. Smith, and N, A, Webb. 1971. Pre- liminary report on maturity, spawning season, and larval iden- tification of rockfishes iScorpaenidae) collected during 1970. Fish. Res. Board Can. Manuscr. Rep. 1137, 26 p. cannot be inferred. The wide range of lengths of pelagic specimens, 8 to .30 mm in April, 9 to 36 mm in May, 18 to 57 mm in July, indicates spawning may be variable and protracted. Benthic juveniles were taken March through July. In trawl surveys off Oregon, adults ranked sec- ond in biomass only to S. diploproa of all rockfishes collected over the continental slope and fifth or sixth on the continental shelf (Demory et al. 1976). Snytko and Fadeev ( 1974) reported it to be one of the most abundant trawl-caught rockfish species over the slope together with S. alutus, S. saxicola, and S. diploproa. This species was one of the three major contributors to the 1963-71 Ore- gon landings of the Pacific ocean perch fishery exceeding ,S. alutiis in 1971 (Niska 1976). Al- though little can be said about the actual abun- dance of larvae and juveniles off Oregon because of the various kinds of samples examined and irregu- lar nature of the sampling effort, they were one of the more common kinds relative to the other species of Sebastes in the samples. SEBASTES PINNIGER (GILL) (Figures 7, 8, 9) Literature. — Pigmentation of preextrusion larvae of S. pinniger was listed in tabular form by Wes- trheim (1975). Newborn to 2-wk-old larvae were described by Waldron (1968) and the older larva was redrawn by Moseretal. (1977). Mean length of larvae at hatching is 3.6 mm SL. Newborn lar- vae have an irregular double row of pigment (usu- ally <16 melanophores) along the ventral midline between the 18th and 22d myomere and some pigment above the yolk sac near the anus. After 2 wk additional melanophores are present at the tip of the lower jaw, on the ventral part of the yolk sac, on the pectoral fins, along the dorsal midline in an irregular double row between the 19th and 21st myomeres, and in the hypural region. The ventral midline melanophores may extend as far forward as the 14th myomere. Identification (Table 7, Appendix Tables 2-6).— A total of 269 specimens of S. pinniger, 7.9 to 181 mm long, were identified. Juveniles were iden- tified using the following combination of charac- ters compiled from specimens in our collections: Gill rakers = 40-45, left arch; 38-46, right arch Lateral line pores = 40-45 Pectoral fin rays = 16-18, usually 17 19 FISHERY BULLETIN VOL 77. NO 1 8.9 mm 9.8 mm I4.lmm Figure 7.— Planktonic larvae (8.9. 9.B mm.l and transforming specimen (14.1 mm) of Sebastes pinniger. 20 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES 16.2 mm 20.0 mm 29.4 mm Figure 8. — Transforming specimen 1 16.2 mmi and pelagic juveniles i20.0, 29.4 mm) of Sebastes pinniger. 21 FISHERY BULLETIN VOL, 77. NO 1 40 mm 59.4 mm Figure 9. — Pelagic juvenile (40.0 mm) and benthic juvenile (59.4 mm) of Sehastes pinniger. Anal fin soft rays = 7 Dorsal fin soft rays = 13-15, usually 14 or 15 Supraocular spine = present Interorbital space = flat to convex. Large juveniles ( >26 mm SL) have the black blotch at the base of the posterior half of the spi- nous dorsal fin characteristic of adults. Other Sebastes juveniles which have a black blotch, e.g.. S. nu'lanops, S. //ac/f/w.s, S. cranieri, do not agree with the characters given above. Of the Sebastes species occurring off Oregon, S. pinmger has the best fit to all these characters. Sebastes rmniatus and S. emphaeus also agree with many of the counts. However, juvenile S. iiiiniatus and S. em- phaeus lack a black blotch at the posterior base of the spinous dorsal fin. Sebastes mtniatus usually has 18 rather than 17 pectoral rays, and S. em- phaeus lacks supraocular spines. The larvae and juveniles in the series in question were among the most abundant in our collections. Adult S. pin- niger are known to be abundant in trawlable areas offshore whereas S. miniatus are not commonly taken (Demory et al. 1976; Niska 1976). Sebastes emphaeus, although not previously reported from Oregon, is well represented in our samp'es. Fig- ment pattern, general body shape, time of occur- rence, and constancy in number of anal fin soft rays and pectoral rays helped link the dev iop- mental series together. 22 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Table?. — Meristics from larvae and juveniles of Se6as/espmni^<>r off Oregon, based on unstained specimens. Specimens above dashed line are undergoing notochord flexion. All specimens had 8 superior and 7 inferior principal caudal fin rays and 7 branch iostegal rays on each side. standard length (mm) Dorsal fin spines and rays Anal fin spines and rays Pectoral fin rays Pelvic fin spines and rays Left Rigtit Gill rakers (first arcti) Lateral line pores Diagonal scale Left Riglit Left Rigtit Left Right rows 78 78 CI — f7 17 — M') IV) — — — — — 88 Vllltl=.14 III5.7 8.9 IX^IMS IIIJ.7 93 XIIP,14 IIP.7 98 XIIP,14 IIP.7 107 XIII3.14 IIP,7 107 XIIIMS ll|5,7 109 XIIIM5 IIP,7 123 XIIP.15 IIIJ.7 12 3 XIIIM4 1IP.7 ■■128 XIII3.15 IIIJ.7 M30 XIIP,14 IIP.7 '14 1 Xll|5,14 IIP. 7 "142 XIIP.U lll'.7 ■■152 XIIIM5 lll'.7 "160 XIIIM4 IIP.7 "160 XIIIM4 III5.7 "162 Xll|5,15 IIP7 "168 Xll|5.t4 IIIJ.7 "178 XIII5.15 IIP.7 "18 4 XIM5.14 IIP.7 M86 XIII, 16 III.7 ^■189 XIII.IS III.7 M94 XIII.IS 111,7 5195 XIII.14 111,7 520 XIII.14 III.7 520 8 Xlll,14 111,7 522 4 XIII.14 III.7 523 4 XIII.14 111,7 526 4 Xlll,14 IM.7 526 4 XIII.14 III.7 526 6 XIII.IS III.7 528 6 XIII.14 III.7 528 8 XIII.15 III.7 529 4 XIII.14 III. 7 530 4 XIII.13 III.7 530 9 Xlll,14 111,7 534 1 XIII.14 III.7 538 XIII.14 III.7 538 7 XIII.IS 111,7 5392 XIII.14 '11.7 5400 XIII.14 l'l,7 541 XIII.14 .117 542 4 XIII.IS 111,7 5594 XIII.14 111,7 5117 7 Xlll,14 111,7 5181 XIII.IS III.7 17 17 18 17 17 17 17 17 17 17 17 17 17 17 17 18 17 18 17 17 17 17 17 17 17 17 17 17 17 1- 16 17 17 17 17 17 1; 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 18 17 17 18 17 17 17 17 17 17 17 17 ■7 17 17 17 I.S IS 1.5 I.S 1,5 1,5 IS 1.5 I.S 1.5 I.S 1,5 1.5 15 1,5 1,5 1,5 I.S I.S 1.5 IS 1.5 1,5 1.5 1.5 I.S 1.5 1,5 1.5 1 ; i.f I.S 1.5 1,5 1.5 1.5 1.5 15 l.i 1.5 1.5 I.S 1,5 1.5 1,5 1,5 1,5 — — — IS — — — 1.5 _ _ — 1.5 — — — I.S — — — 1,5 — — — 1,5 — — — 1,5 — — — I.S — — — I.S -~ — — 1.5 — _ — 1.5 — 27- 12 or 13 = 39 or 40 — 1,5 — — — 1,5 — — — 1,5 — 28+13=41 — 1,5 — — — 1,5 — 27 + 13=40 — 1.5 — _ — I.S — 27 + 12 = 39 — I.S — — — 1,5 27-14=41 28-14=42 — 1.5 29-13=42 28-13=41 _ 1,5 27*13=40 26' 12-38 — 1,5 27-13=40 27-12 39 — 1,5 27-14=41 28-13-41 44 1,5 28-13=41 28-13=41 — I.S 28-13 = 41 29-13=42 _ IS 29*13=42 28-14=42 -44 1.5 29+15=44 29 + 14 = 43 -43 I.S 28- 14=^42 2d -13=41 — 1,5 28-13 = 41 29 + 14=43 — IS 28-13=41 29*14 = 43 »42 IS 29-13 = 42 28-13 41 — 1.5 28- 13 = 41 28 + 14=42 -44 1.5 28-13 = 41 28 + 13 41 «44 1.5 31 14 = 45 31 + 15-46 — 1,5 29-14=43 29 + 14=43 .44 l,S 28*14 = 42 29 + 14=43 — 1,5 27-13 = 40 29+i:.=42 =42 1,5 29-14=43 29+1 4 43 =41 1.5 28 + 14=42 29 + 13=42 40 1,5 30-14=44 30-1- 44 — I.S 29-14 = 43 29-14 = 43 1,5 29-14=43 29-14 = 43 :.,_ l,S 29-14 = 43 29- 13-42 45 1.5 30-14=44 28-14=42 43 =44 =40 x44 «42 «44 =41 43 40 43 44 43 =51 =50 'Forming ^Not formed ^Postenormost dorsal or anal spine appears as a soft ray "Transforming 5Pelagic luvemle 5Benthic juvenile Distinguishing Features. — Characters useful in distinguishing the smallest larvae (7.8 mm) of S. pintager identified from our collections are the presence of remnants of both dorsal and ventral midline melanophores the anterior of which are nternal, the lightly pigmented pectoral fins, melanophores at the tip of the lower jaw and on the anteroventral margin of the maxillary, the pres- ence of one or two large external stellate melano- phores on the (i- sum just posterior to the parietal spines, the relatively deep body (40'7f SL), long parietal spines (24'^f HL), and long pectoral fins (25% SL). Later stage larvae are characterized by their relative lack of pigment on the trunk except over the gut, together with the relatively deep body and long parietal and third posterior preopercu- lar spines. Meristics, presence of the supraocular spine, flat to convex shape of the interorbital space, and dark blotch at the base of the spinous dorsal serve to distinguish the juveniles. 23 FISHERY Bl'M-ETIN VOL 77. NO. 1 General Development. — The smallest larvae of S. pinniger identified, 7.8 mm, are in the final stage of notochord flexion. By the time larvae are 8.8 mm long, fle.xion is complete. Transformation to pelagic juvenile begins in larvae -12.5 mm long with the initiation of spine formation in the dorsal and anal fin "prespines" and the appearance of a patch of melanophores on the dorsum immediately posterior to the second dorsal fin. Transformation of the "prespines" to spines is complete in speci- mens > 18.6 mm and some pigment has been added beneath the first dorsal fin marking the beginning of pelagic juvenile pigmentation. The dorsal pig- mentation becomes more pronounced during the pelagic juvenile period which lasts until ~40 to 50 mm. The largest pelagic juvenile taken was 42.4 mm and the smallest benthic juvenile was 59.4 mm. Morphology (Tables 4, 8). — Forty-eight specimens of S. pinniger. 7.8 to 181.0 mm long, were mea- sured for developmental morphology. Larvae ap- pear quite deep bodied, but body depth at the pec- toral fin ba.se decreases considerably during the pelagic period from 40 to 33'r SL. In comparison, body depth at the anus/SL changes relatively lit- tle, decreasing slightly then increasing. Snout to anus length increases from 59 to 64'^( SL while snout to pelvic fin distance increases to a lesser degree. Head length decreases from 43 to 37*^^ SL during development as more marked changes occur in eye diameter, decreasing from 37-39 to 27'r HL, and interorbital distance, decreasing from 37 to 20Cf HL. Upper jaw length/HL first decreases and then increases while snout length/HL increases then decreases. The length of the angle gill raker in- creases with respect to head length from 1 1 to 14 or 15'7f. Larvae and young juveniles up to 24 mm have a prominent symphyseal knob directed anteroven- trally. It becomes less obvious with development and is barely noticeable by the time juveniles are 29 mm long. Fin Development (Tables 4, 7, 8). — Pectoral fins are present and the adult complement of 16 to 18 (usually 17) rays can be counted in 7.8 mm larvae of S. pinniger. although the ventral rays are not fully formed until >8 mm. The pectoral fins are relatively long in flexion and postflexion larvae averaging 2.5''( SL and they maintain this approx- imate proportion through development. Depth of 24 the pectoral fin base decreases from 15 to 9'/f SL. Developing pelvic fins are visible on 7.8 mm larvae and the adult complement of I, 5 is count- able in postflexion larvae of 8.8 mm. The pelvic fins are rather long, averaging 14'^f SL in flexion larvae and increasing to a maximum of 23'^f SL in transforming specimens. Length of the pelvic spine, always less than the fin itself, increases from 5^'<- SL in flexion larvae to 2Cf( in transform- ing specimens then decreases to 1.3''f in benthic juveniles. The adult complement of principal caudal rays can be counted in 7.8 mm larvae, before the com- pletion of notochord flexion at 8.8 mm. Counts of secondary caudal rays were 11 superior and 12 inferior rays on each of two stained juveniles, 29.5 and 33.4 mm. Bases of some of the dorsal and anal fin ray and spine elements are visible on the 7.8 mm larvae. The adult complement of ray and spine elements is present in postflexion larvae >9 mm and the rays and spines (with "prespines") appear fully formed by 9.3 mm. Transformation of "prespines" to spines is completed by 18.5 mm. The longest dorsal spine increases from 20 to 38'? HL during the pelagic period. The longest dorsal ray increases from 32 to 42 or 439*^ . The longest anal spine in- creases from 19 to 37'7( HL during pelagic de- velopment. Spmation (Tables 4, 9). — Spines present on the left side of the head of the two smallest specimens of S. pinniger, 7.8 mm, include the parietal; the nuchal; the first and third anterior preopercular; the second, third, and fourth posterior preopercu- lar; the postocular, the pterotic, the inferior post- temporal; the first spine of the inferior infraorbital series; and the first spine of the superior infraorbi- tal series. The parietal spine and ridge are heavily and relatively deeply serrated in small larvae and the spine is relatively long, averaging 24'f HL in flex- ion larvae. Its relative length decreases with de- velopment to 20^7^ HL in flexion larvae, 10^ in transforming specimens, and 77c in early pelagic juveniles, <20 mm. The much smaller nuchal spine averages 4 or 57r HL in postflexion and transforming larvae, decreasing to 19f in benthic juveniles. The parietal and nuchal spines fuse to- gether, beginning in pelagic juveniles -20 mm until only the nuchal tip is visible in juveniles >40 mm. Serrations along the parietal ridge can be seen on specimens up to 39 mm. RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Table 8. — Measurements (millimeters) of larvae and juveniles of Sebastes pinmger from waters off Oregon. Specimens above dashed Ime are undergoing notochord flexion. o — t- £ en c li S O) 0) — I O OJ c — CO S (U c E ra »-□ UJ Is £•5 c ra _ n O 0) c m£ Q- C Q. is CL h - 111 3 c o -t 78 98 4.6 3-3 0.88 1,6 12 1 2 32 2 1 21 1 1 40 1 2 3.4 0.80 (') 1 2 — (*) (') (') 78 95 45 3.4 0.92 1 6 13 1 3 3 1 22 1 8 1 2 C) 96 30 084 C) 1 1 — (^1 (») .......... 88 11 2 55 42 1 22 1 5 1 4 37 25 2 1 1 2 72 88 36 — _ 1 2 _ _ 1 8.9 11 1 46 34 92 1 4 1 4 1 3 30 22 1 8 1 2 88 1 1 34 76 016 1 2 — 46 1 1 (=) 93 11 5 56 40 1 3 1 9 1 5 1 4 35 26 2 1 1 2 1 2 1 4 38 94 10 1 4 — 52 1 1 {') 98 123 58 4 1 1 2 1 9 1 6 1 5 38 30 2 7 1 2 — 1 7 34 96 18 1 6 34 — 1 3 60 107 14 1 66 4 7 1 3 22 1 9 1 6 43 32 27 1 4 — 1 9 48 — — — 054 1 1 1 5 1 107 134 63 46 1 6 20 1 9 1 4 39 29 27 1 3 1 6 23 4 7 — — 1 2 48 1 1 4 88 109 128 63 45 1 2 22 1 8 1 5 43 33 — 1 4 1 6 20 44 — — 1 5 44 92 1 4 84 123 155 77 50 1 3 2 1 1 9 1 7 4 4 34 30 1 4 — 24 4 9 44 18 1 6 56 — 1 9 1 123 154 76 52 1 6 — 2 1 1 7 48 3 7 35 1 4 — 28 52 — 36 1 3 64 1 5 1 9 — '128 157 80 52 1 9 2 1 20 1 6 4 5 34 29 1 3 24 27 59 66 18 1 3 70 1 5 1 6 1 3 '130 152 82 55 1 7 2 1 2 1 1 6 4 8 3 5 35 1 5 — 27 59 60 30 1 6 68 1 3 20 1 1 '14 1 17 1 85 59 21 21 22 1 7 49 35 — 1 5 26 30 60 68 32 1 3 68 — — 1 5 '142 168 86 57 1 6 — 22 1 8 5 1 39 — 16 25 30 58 — 36 1 3 72 1 7 22 1 5 '152 192 9 1 62 1 9 28 23 20 54 4 3 43 1 7 3 1 3 7 62 80 40 1 5 84 1 9 24 1 8 '160 20 94 62 1 7 28 24 20 59 4 5 45 1 8 — 38 62 — 28 1 4 80 24 — 20 '160 208 93 66 1 7 31 25 20 57 4 5 4 5 1 6 — — 62 26 18 1 4 088 — 24 1 7 '16.2 20 6 102 69 1 9 32 26 20 62 50 5 1 1 8 — 4 1 6 7 — 50 1 6 90 28 29 — '166 197 10 1 67 2 1 28 2 5 1 9 63 4 7 4 5 1 8 — — 65 — 34 1 6 88 22 25 — '178 20 8 107 70 22 28 27 20 64 52 48 1 8 36 4 1 76 — — 1 6 090 — 28 — '184 21 8 107 70 1 9 28 25 22 64 5 1 4 4 20 40 4 4 75 72 16 1 6 94 — 30 27 «186 22 9 11 7 76 23 33 26 20 62 4 7 50 1 8 36 42 86 70 32 — 1 1 26 32 26 «189 23 5 11 7 7 7 24 33 2 7 2 1 64 48 — 1 9 36 4 1 84 — — 1 6 09 — — 24 "194 23 4 11 2 80 19 34 27 22 66 54 52 1 9 4 2 46 76 46 30 1 7 1 1 — 31 26 "195 24 6 115 82 22 3 5 28 22 67 52 — 20 43 46 66 84 44 1 4 1 30 — 2 7 "20 25 4 11 5 74 1 8 34 28 22 74 56 5 7 20 — 46 80 40 30 — 1 1 — 32 28 "20 8 24 8 126 80 26 3 1 28 21 70 53 59 20 39 42 85 Joined 32 1 2 1 2 — — 27 •22 4 26 7 130 84 20 34 30 23 7 7 59 60 22 45 52 80 Joined 26 1 4 1 2 — — 32 '234 28 8 13 1 78 2 1 3 7 33 24 80 63 6 1 2 1 4 7 5 1 77 Joined 28 — 1 2 36 38 33 "26 4 33 4 15.2 9 1 2 1 4 2 35 26 89 70 73 25 — 60 99 Joined 40 1 4 1 5 — 40 40 "26 4 312 173 104 34 40 34 24 89 70 72 24 46 55 120 Joined 20 1 2 1 5 — — 32 "26 6 32 170 10 6 26 42 34 22 89 7 1 7 1 24 48 6 1 109 Joined 40 — 1 4 — — 36 "28 6 38 1 179 107 30 40 35 27 92 73 76 26 — 64 1 1 4 Joined 28 1 3 1 5 — 42 4 1 •28 8 36 3 192 106 34 43 3 7 26 96 76 76 26 52 62 13 1 Joined 30 1 2 1 5 40 4 1 4 4 "29 4 37 1 179 10 1 26 4 1 37 27 105 80 7 5 28 52 66 107 Joined 28 1 2 1 6 44 4 4 4 4 "30 4 38 1 20 5 11 5 3 7 49 3 7 26 10 1 7 5 7 7 25 52 65 134 Joined — 1 2 1 6 44 4 4 4 4 "30 9 38 6 20 8 130 4 1 45 40 27 104 81 86 28 55 72 134 Joined — 1 2 1 6 46 46 — "34 1 42 6 22 7 125 39 53 4 27 11 83 — 28 5 7 66 155 Joined 34 1 5 1 6 4 4 48 48 "38 46 6 22 5 138 30 57 4 7 30 11 6 9 1 93 31 — 7 7 14 1 Joined 30 1 3 1 9 49 57 53 "387 46 4 23 4 133 33 60 4 5 29 120 98 96 34 66 78 142 Joined 46 1 4 2 1 54 — — "39 2 48 8 23 5 139 32 59 4 5 30 11 7 10 1 102 33 57 80 146 Joined 30 1 3 1 9 — 6 1 53 "40 49 1 23 5 149 36 60 4 7 33 12 5 104 96 36 65 88 155 Joined 30 1 4 2 1 53 66 63 "41 50 4 25 14 7 43 59 46 31 122 98 104 34 63 84 178 Joined 30 1 5 2 1 56 66 55 ■42 4 51 7 26 4 154 4 3 5 7 49 30 130 11 102 37 64 87 165 Joined 40 1 4 2 1 51 63 52 »59 4 71 36 21 8 64 93 66 40 194 162 136 51 74 11 3 24 4 Joined 46 1 4 30 7 4 89 75 '1177 141 8 78 3 43 8 125 195 11 2 86 41 6 33 2 29 4 10 1 148 25 5 48 3 Joined 64 1 7 66 138 174 142 »181 224 1172 65 4 18 1 30 6 159 137 67 2 61 5 45 1 163 218 41 2 83 5 Joined 70 2 3 106 26 7 30 9 23 9 'Usually third or fourth in larvae, fifth or sixth in juveniles ^Usually midfin ^The second spine *Bump ^Not formed ^Forming 'Transforming "Pelagic juvenile 'Benthic juvenile The posterior series of preopercular spines are prominent in S. pinmger larvae. The heavily ser- rated third spine is relatively long averaging 32 to 34'7( HL in flexion and postflexion larvae. Its relative length then decreses to 5^f in benthic juveniles. All five spines of the series are present in larvae >10 mm. Serrations are visible on the second, third, and fourth spines until =29 mm. The first posterior preopercular spine is some- times bifid in pelagic juveniles. The smaller first and third spines of the anterior preopercular series are also conspicuous on small larvae, but decrease in prominence until they are no longer visible in pelagic juveniles >26 mm. The second anterior preopercular spine never becomes appar- ent. 25 FISHERY BULLETIN: VOL, 77. NO. 1 The superior opercular spine is present on lar- vae by 9 mm and the inferior opercular spine ap- pears later in larvae —12 or 13 mm. Both spines are present on juveniles. An interopercular spine develops on the edge of the gill cover, usually in larvae >10 mm. A subopercular spine was not present on any of the specimens examined. The ridge anterior to the postocular spine is heavily serrated and remains so until preocular spine formation. The preocular appears first as a bump in transforming larvae =16.0 mm long and develops into a spine in pelagic juveniles >19 mm. Development of the supraocular follows a similar pattern appearing at about the same time as the preocular. Beneath the eye the fourth spine of the superior infraorbital series is present in larvae >9 mm and the third spine of this series is present in all larvae >13 mm. The second superior infraorbi- tal spine never forms. All three superior infraorbi- tal spines disappear by 43 mm. The second spine of the inferior infraorbital series is present on speci- mens >10 mm and the two spines in this series persist in juveniles. The third inferior infraorbital spine never develops. The nasal spine develops T.^BLE 9. — Development of spines in the head region of Sebastes pinniger larvae and juveniles. Specimens above dashed line are undergoing notochored flexion. + denotes spine present and - denotes spine absent. 88 8.9 9.3 9.8 10.7 10.7 10.9 12.3 123 M2.8 '13.0 '14 1 '142 '15.2 '160 '160 '16.2 '16.8 '178 '18 4 '186 M8.9 J 19.4 M9.5 =20.0 ■1208 =22.4 123 4 '264 =26.4 =26 6 =28.6 =28.8 =29.4 =30 4 =30.9 =34.1 =38.0 =387 '39.2 =40.0 '41 =42.4 «594 *117.7 6181 Standard length Parietal Nuchal Preopercular (anterior series) 1st 2d 3d Preopercular (posterior series) Opercular Superior Inferior Inter- oper- cular Sub- oper- cular Pre- Supra- ocular ocular Post- {mm) 1st 2d 3d 4th 5th ocular 7.8 78 » + + - + + - + - >- -- + ~ ~ " ~ - 4 + + {') 4- 4- i') {') + - + + (') + + i') f 4 {') (') {') (^) n (') + + + + 'Transtorming, -'Bump tndicates beginnrnq of spine formation ^Pelagic luvemle ■'Spine IS bifid ^Parietal and nuchal spines fused ■^Benthic juvenile ^Spine has become rounded, no sharp tip 26 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Table 9.— Continued. Infraorbitals Nasal Posttemporal Coronal Tympanic Rerotc Superior Interior Standard length (mm) Inferior Supenor Supra- 1st 2d 3d isl 2d 3d 4th cleithral Cleithral 78 78 4- - - - - - — — + - + - - + - + - 8.8 + - 8.9 + - 9.3 + - 9-8 + - 10,7 + + 10.7 + + 10.9 + + 12.3 -f + 12.3 + + M2.8 + + •13.0 + + '14.1 + + M4.2 + + M5.2 + + M6.0 + + M6.0 + + '16.2 + + '16.8 + + '17.8 + + '184 + + 318.6 + + 318-9 + + 319.4 + + 319.5 + + 320.0 + + 320-8 + + 3224 + + 323.4 + + 326.4 + + 326.4 + + 326,6 + + 328.6 + + 328.8 + + 329,4 + + 330-4 + + 330.9 + + 334.1 + + 338.0 + + 338,7 + + 339.2 + + 340.0 + + 341.0 + + 342,4 + + 659.4 + + 61177 + ^ + M81 + ' + 7 {') + + + + + + + + + + + -I- (^1 first as a bump in larvae >9 mm and is present in juveniles. The tympanic spine appears on specimens >35 mm SL. This spine forms at the anterior edge of a foramen of the cephalic lateral line system. The pterotic spine, present in the smallest larvae, dis- appears in benthic juveniles. The supracleithral spine develops posterior to the inferior post- temporal on larvae >9.5 mm and the superior posttemporal spine is present dorsal to these in specimens >14 or 15 mm. This latter spine is occa- sionally bifid. The inferior posttemporal disap- pears in benthic juveniles. Posterior to the opercle the cleithral spine is visible in pelagic juveniles of 19.5 mm and persists in benthic juveniles. Scale Formation . — Lateral line pores are visible on specimens >17 mm. Scale formation has begun on juveniles >23 mm. Pigmentation . — The smallest larvae of S. pinniger examined, 7.8 mm (similar to the 8.9 mm speci- men illustrated), have pigment on the head over the brain. Melanophores line the inner tip of the lower jaw and a few are present along the antero- ventral margin of the maxillary. In the abdominal region, an internal melanistic shield covers the dorsal half of the gut, appearing darkest on the dorsal surface. A few additional melanophores are present along the ventral midline of the gut cav- ity. Two or three lai-ge stellate melanophores are 27 FISHERY BULLETIN: VOL. 77, NO, 1 on the dorsum immediately posterior to the parietal spines. In the tail region several embed- ded melanophores, sometimes fused, are on the dorsal and ventral body midlines near the caudal peduncle. These midline melanophores are pres- ent in the same region as the midline pigment shown on Waldron's (1968) reared 2-wk-old lar- va. The pectoral fin blades are lightly pigmented with elongate melanophores. Melanophores are also present on the inner side of the pectoral fin base but not on the outer side. The pelvic fins also have a light scattering of melanophores. The caudal fin base is unpigmented. During larval development, pigment increases on the head over the brain. Occasionally one or two melanophores are present on the snout. Melano- phores lining the inner tip of the lower jaw and those on the anteroventral margin of the maxil- lary remain throughout the larval period. The melanistic shield over the gut intensifies laterally and melanophoreson the ventral midline disappear. The two to three stellate melanophores on the dorsum posterior to the parietal spines dis- appear by the time larvae are 9 mm long. In the tail region, the dorsal and ventral midline melanophores near the caudal peduncle are no longer visible on larvae >9 mm. The rayed portions of the pectoral and pelvic fins remain lightly pigmented during the larval period but melanophores are no longer present on the inner side of the pectoral fin base in larvae >10 mm. During the transformation period, 12.8 to 18.6 mm, the amount of pigment increases gradually. In the head region, internal pigment is added to the opercle dorsally until a patch of 6 to 10 melanophores is visible on specimens >16 mm. Internal gut pigmentation decreases in intensity due to overgrowth by musculature. A few melano- phores sometimes appear on the nape and beneath spines V to XI of the first doral fin, although not consistently until late in the transformation period in specimens >17 mm. The most prominent addition of pigment occurs dorsally in the tail re- gion just posterior to the soft dorsal fin. Melano- phores are added along the dorsolateral surface of the caudal peduncle. Directly below these melanophores, three or four internal and one to four external melanophores are added along the lateral midline in specimens >15 mm. The amount of pigment on the pectoral and pelvic fins decreases during this period. During the pelagic juvenile period, 18.9 to 42.4 mm, new pigment is added over the dorsal surface of the head, interorbital, snout, premaxillary (specimen >26 mm), and on the lower jaw (speci- men >35 mm). The opercular patch enlarges. Around the eye, melanophores are added first on the posteroventral margin of the orbit in speci- mens 19 to 23 mm, and eventually line the orbit. A radiating bar of melanophores begins to extend from the posteroventral margin of the orbit on specimens >28 mm, extending onto the preopercle on specimens -30 mm. In the abdominal region, melanophores are added dorsolaterally to the nape and beneath spines V to X of the first dorsal fin forming two pigment patches connected by a dor- sal row of melanophores by 23 mm. The nape patch expands forming a saddle ( first in position) extend- ing from the parietal spine to the third dorsal spine and ventrally to the superior posttemporal spine by 28 mm. Two saddles (second and third) develop from the pigment patch beneath the spi- nous dorsal fin, midfin beneath spines IV to VI and posteriorly beneath spines VIII to XI. These two saddles are separated by a relatively unpigmented area on the dorsum. As they extend more ven- trolaterally, they fuse together in two places just above and below the lateral line creating a second, circular, less pigmented area on specimens >39 mm. These two saddles eventually extend to the dorsal portion of the gut cavity by 42 mm. A single external melanophore may occur on the midan- terior margin of the eleithrum beneath the gill cover. In the tail region, the dorsal patch of pig- ment on the caudal peduncle extends to the lateral line forming another saddle by 23 mm which reaches the ventral body margin by 27 mm. Be- neath the second dorsal fin melanophores increase in number and become concentrated along the muscles surrounding the dorsal pterygiophores appearing as vertical lines of pigment by 23 mm. Melanophores also develop at thepoint of articula- tion of all but the anteriormost three or four dorsal soft rays. A melanistic saddle (fourth in position) develops beneath soft dorsal rays 3 to 12 or 13 extending ventrolaterally to the body midline by 34 mm and three-fourths the distance to the ven- tral margin by 42 mm. The pectoral and pelvic fins are no longer pigmented in specimens >21 mm Pigment develops on the first dorsal fin membrane between spines IX and XI in juveniles '26 mm, eventually forming the "black blotch" characteris- tic of larger juveniles and adults. Melanistic bars form on the first dorsal fin between spines I to III 28 RICHARDSON and LAROCHE DEVELOPMENT AND OCl'URRENCE OF ROCKFISHES and V to VIII above the first and second saddles. By 39 mm the outer half of the fin is completely pigmented, while two unpigmented areas remain on the proximal half of the fin between the two pigment bars. Melanophores are added on the sec- ond dorsal fin above the fourth saddle until the proximal one-fourth of the fin between rays 2 and 13 or 14 is pigmented. The base of the caudal fin never becomes outlined with melanophores, but some melanophores develop on the dorsal second- ary caudal rays. Recently preserved pelagic juveniles of S. pin- niger, 32 to 35 mm, are covered with orange chromatophores which are lost during prolonged preservation. They are present on the dorsal part of the head, on the snout, around the orbit, and on the opercle. On the body they are concentrated along the myosepta and lateral midline, with greater numbers on the dorsal half of the body but also e.xtending to the ventral margin. Orange chromatophores are also concentrated on the spi- nous dorsal fin, along the basal one-fourth of the caudal fin, and the anal fin membrane around the anal spines. A general increase in melanistie pigmentation occurs in benthic juveniles >59 mm. On the head, the two pigment bars beneath the orbit remain distinct and extend over the operculum. Pigment increases between the saddles obscuring the pat- tern seen on pelagic juveniles. Melanophores are added to both the inner and outer surfaces of the pectoral fin base and on the basal one-third of the pectoral fin blade. The pelvic fin remains unpig- mented. The addition of melanophores to the spi- nous dorsal fin obscures the pattern seen on pelagic juveniles although the black blotch re- mains intense and distinct. The entire caudal fin is lightly pigmented with more intense pigment oc- curring over the bases of the primary rays and all upper secondary rays. Occurrence (Figures 10, 11). — Adults of S. ptn- ntger occur between Cape Colnett, Baja Califor- nia, and southeast Alaska (lat. 56" N, long. 134° W) (Hart 1973). Off Oregon they are most common on the continental shelf between 100 and 200 m (Snytko and Fadeev 1974). A major population concentration has been found between lat. 44°30' and 45" N off Oregon (Snytko and Fadeev 1974). :Li.-^_ iui £ <^ 10 MAR -H 1 H/—< 1 APR -I 1 w^^ 1 MAY JUN '< II f AUG 40 60 60 100 Standord Length (mm) 120 180 190 Figure ll. — Seasonal occurrence of larvae and juveniles of Sebastes pinniger off Oregon. Data from 1964 to 1975 combined. Dashed line separates pelagic and benthic stages. ■^ .' : 4 1 ^ •• • /." - Larvae Pelagic Juveniles TIj" T r f Benthic Juve uveniles Figure lO. — Number of specimens and location of capture of larvae and juveniles of Sefeasfespjnm^er off Oregon 1 1964-75 1 described in this paper- 29 FISHERY BULLETIN; VOL, 77, NO 1 Larvae, including transforming specimens, of .S. pinnigcr in our collections were captured at a wide range of stations from 13 to 306 km offshore. The largest numbers and smallest larvae (<8.8 mm) were taken at stations 83 to 120 km off Newport beyond the continental shelf break. This may partly be a reflection of increased sampling effort in that area. Pelagic juveniles occurred at a simi- lar wide range of stations, mostly beyond the con- tinental shelf Interestingly, 30 specimens, rang- ing in length from 8.9 to 18.6 mm were captured 306 km off Coos Bay, Oreg., well beyond the conti- nental shelf Perhaps this wide ranging offshore occurrence of larvae and pelagic juveniles is re- lated to their morphology. The larvae are quite stubby and deep bodied with particularly long head spines, features which could contribute to increased flotation and dispersal by currents. Most specimens were captured in oblique midwater trawl and bongo net tows. Three benthic juveniles were taken close to the coast in depths of 30 to 35 m. Reported spawning times for S. pinniger are November to March off California (Phillips 1964i and January to March off Oregon, Washington, and British Columbia (Westrheim 1975). Larvae <10 mm were taken March through June, and larger pelagic specimens were taken March through August. The wide range in lengths, 9 to 25 mm in March, 7 to 38 mm in April, 8 to 34 mm in May, 9 to 43 mm in June, may be indicative of protracted and variable spawning. Benthic juveniles were taken in June and August. Sehastes pinniger is one of the most abundant trawl-caught rockfish species on the continental shelf off Oregon together with S. flavidus and S. entomelas (Snytko and Fadeev 1974). In trawl surveys off Oregon it ranked either first or second only to S. entomelas in biomass over the shelf (Demory et al. 1976). It was one of the major con- tributors to "other rockfish" landings in Oregon during 1963-71 (Niska 1976). Larvae and juveniles were the most numerous in available collections of the three species described in this paper. SEBASTES HELVOMACULATUS AYRES (Figures 12, 13) Literature. — Westrheim etal. (see footnote 9) pre- sented a schematic illustration of a preextrusion larva of S. helvomaeulatus and described the pigment pattern in a tabular form. The latter table was also in Westrheim (1975). Preextrusion lar- vae (mean total length =4.1 mm) have a ventral midline row of usually <16 (83"^* of 120 larvae) melanophores which stop short of the anus usually by as much as four myomeres. Pigment is absent from the dorsal midline, the head, nape, and lower jaw, and is usually not in the hypural region. The illustration shows some melanophores over the hindgut and ventrally beneath the yolk sac. Wes- trheim (1975) added that larvae of S. hel- vomaeulatus, along with 10 other species which had been reared for several days, develop pigment spots on the head, nape, and/or lower jaw. Identification (Table 10, Appendix Tables 2-6). — Twenty-six specimens of S. helvomaeulatus, 7.7 to 183 mm long, were identified. Juveniles were identified using the following combination of characters obtained from specimens examined in this study; Gill rakers = 28-31 Lateral line pores = 35-43 Pectoral fin rays = 15-17, usually 16 Anal fin soft rays = 5-6, usually 6 Dorsal fin soft rays = 12-14, usually 13 Supraocular spine = present Interorbital space = concave. Of the Sebastes species occurring off Oregon, S. helvomaeulatus has the best fit to the above characters. Sebastes aurora and S. elongatus also agi'ee with many of these characters, butS. aurora was eliminated since it has 24 to 28 gill rakers and S. elongatus was eliminated since it does not have a supraocular spine. Larval and juvenile speci- mens of S. elongatus identified from our collec- tions are noticeably more slender than specimens of S. helvomaeulatus and also are pigmented dif- ferently. Pigment pattern, body shape, time of oc- currence, and constancy in number of anal fin soft rays and pectoral fin rays helped link together the developmental series. Distinguishing Features. — Characters useful in distinguishing the smallest larva of S. hel- vomaeulatus identified, 7.7 mm, are the pig- mented fringes of the pectoral and pelvic fins; the general lack of body pigment; melanophores in- side the tip of the lower jaw; narrow interorbital distance (317f HL); long, deeply serrated, parietal spines (27% HL); and relatively long pectoral fins 30 RICHARDSON and LAROCHE; DEVELOPMENT AND OCCURRENCE OF ROCKFISHES 8.0 mm 10.9 mm 13.4 mm FIGURE 12. — Planktonic larvae (8.0, 10,9 mml and transforming specimen (13.4 mm) o( Sebasles helvomaculatus. 31 FISHERY BULLETIN: VOL. 77, NO, 1 <. ^^,,, < 18 4 mm ^/y^A 41 6 mm ■^ Figure 13. — Transforming specimen (18.4 mm) and pelagic juveniles (22.4, 41.6 mm) of Sehastes helvomaculatus . {2A'7c SL). Later stage larvae change very little in larva to pelagic juvenile. Meristics, presence of a appearance from the smallest larva, except for an supraocular spine, the concave shape and narrow increase of dorsolateral internal gut pigment. A width of the interorbital space, the patch of distinctive pigment patch appears on the caudal melanophores on the caudal peduncle, and the peduncleduring the period of transformation from single melanistic pigment saddle extending pos- 32 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Table 10.— Meristics from larvae and juveniles of Sebastes helvomaculatus off Oregon, based on unstained specimens Specimens above dashed line are undergoing notochord flexion. All specimens had 8 superior and 7 inferior principal caudal fin rays and 7 branch iostegal rays on each side. Standard length (mm) 77 80 80 Dorsal Anal fin fin spines spines and rays and rays Pectoral fin rays Right Pelvic fin spines and rays Left Right Gill rakers (first arch) Lateral line pores Right IIR7 III2.7 16 16 16 16 16 l.(') l.(') I.C) l.(') I.C) I.C) Right Diagonal scale rows 88 — 111^.6 16 99 Xll|2,13 III2.6 16 109 XIIIM3 IIP.6 16 = 120 XIII'.IS 111^6 16 = 120 Xll|2,13 111^.6 16 =134 Xlll',13 lll=,7 16 =134 Xll|2,13 MR 6 16 = 136 XIIP.13 W3 16 = 178 XIII2.12 111^6 16 = 179 Xlll'.12 lll',6 16 = 184 XIIIM3 111^6 16 =184 Xlll',12 111^6 16 = 186 XIIIM3 III.6 16 '198 Xlll,13 III.6 16 '20 3 Xlll,14 111,6 16 ■'21 6 XIII, 13 111,6 16 «22 1 XIII.14 111,6 16 422 2 XIII.13 111,6 16 422 4 Xlll,13 111,6 16 "238 Xlll,12 111,5 16 •41 6 Xlll,13 111,6 16 M364 XIII.13 111,6 16 5183 XIII.14 111,6 17 16 16 16 16 16 16 16 16 16 16 16 16 17 16 16 16 16 16 15 16 16 15 16 1.5 1.5 1.5 1.5 1.5 1,5 1,5 1.5 1.5 1.5 1,5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 — — _ _ 1.5 — — _ _ 1.5 — _ _ 1.5 — _ — _ 1,5 — _ — 1,5 — _ 1.5 — _ — _ 1.5 — 21+9 = 30 _ 1.5 21+9=30 22 + 9 = 31 •42 — 1.5 21+9 = 30 21+9 = 30 _ _ 1.5 21+9 = 30 20+8=28 _ _ 1.5 21+9 = 30 21+9 = 30 42 _ 1.5 19+8-27 19+8=27 — — 1.5 21 +8 = 29 21+8 = 29 .40 _ 1.5 21+9 = 30 20 + 8 = 28 -39 _ 1.5 21+8=29 21+8=29 -39 _ 1.5 20 + 9=29 20+8 = 28 -40 • 40 1 5 20+8=28 20+8=28 -38 -38 1.5 21+9=30 21+9 = 30 =41 -41 1.5 20 + 9 = 29 20 + 9 = 29 -43 -43 1.5 22 + 9=31 22 + 8=30 39 38 1.3 21+9 = 30 21+9=30 35 35 1,5 22 + 9 = 31 22+9=31 40 39 'Not formed •'Posterior dorsal or anal spine appears as a soft ray =Transtormtng •Pelagic juvenile ^Benihic juvenile teriorly from the nape to dorsal spine XI and ven- trally about one-half the distance to the lateral line, all serve to distinguish pelagic juveniles. General Development. — The smallest larva of S. helvomaculatus identified, 7.7 mm, is in the final stage of notochord flexion, which is completed by 8.8 mm. Transformation to pelagic juvenile begins in larvae =12 mm long with the initiation of spine formation in the dorsal and anal fin "prespines" and the appearance of a lateral pigment patch on the caudal peduncle. Transformation of the "pre- spines" to spines is completed in specimens >19 mm at which time some pigment appears beneath the spinous dorsal fin and pigment is added to the dorsal margin of the caudal peduncle pigment patch marking the beginning of pelagic juveniles pigmentation. More pigment is added beneath the first dorsal fin during the pelagic juvenile period although the saddle never becomes pronounced. Additional small external melanophores cover most of the fish by the end of the pelagic juvenile period, which probably lasts until =40-60 mm. The largest pelagic juvenile examined was 41.6 mm and the smallest benthic juvenile was 1.36.4 mm. Morphology (Tables 4, 11). — Twenty-six speci- mens of S. helvomaculatus, 7.7 to 183 mm long, were measured for developmental morphology. Relative body depth/SL changes little at the pec- toral fin base, decreasing slightly then increasing while it generally increases at the anus. Snout to anus distance increases from 56 to 63 or 64% SL and the snout to pelvic fin distance increases somewhat then decreases. Head length increases slightly (41-42*2 ) then decreases (38%) with respect to standard length. Eye diameter decreases (39-32% HL), as do the interorbital distance (31-15% HL) and snout length (32 or 33-27% HL). Upper jaw length in- creases from 44-46 to 52% HL. The length of the angle gill raker first increases (13-15% HL) then decreases ( 1 1% ). Larvae and juveniles <24 mm have a weak symphyseal knob which becomes less obvious with development. Fin Development (Tables 4, 10, 11).— The adult complement of 15 to 18 (usually 16) pectoral fin rays can be counted on the smallest larva, 7.7 mm, of S. helvomaculatus although the ventralmost rays are not fully developed. Pectoral fins are 33 FISHERY BULLETIN: VOL 77. NO 1 Table 1 1. — Measurements (millimeters) of larvae and juveniles of Sehastes helvomaculatus from waters off Oregon Specimens above dashed line are undergomg notochord flexion, E m ? U i n 2 * I .S ^a 2y= -sBfi "£ ).^>™2ca> (OCT £ ti (0 "* — : 3! a? 7 7 95 43 32 1 1 1 5 1 2 1 25 1 6 1 9 96 64 10 30 10 10 - (') (?) I') 60 96 4 4 32 96 1 5 1 3 1 28 1 7 20 1 68 1 2 33 090 004 090 - (') (') (') 80 9.9 46 34 1 1 1 4 1 3 1 26 I 6 1 7 1 66 10 33 78 08 78 (') (') (') 88 10,9 52 39 1 3 1 4 1 4 1 2 29 1 9 22 1 1 40 1 3 36 78 10 1 2 48 {") 80 (*) 99 12,3 58 4 1 1 3 16 1 5 1 3 33 26 24 1 1 1 2 1 6 40 80 22 1 3 56 88 12 60 109 134 65 4 4 1 5 1 8 1 6 1 4 37 28 26 1 2 1 6 1 7 45 70 22 — 62 82 1 3 76 «120 149 74 49 1 6 24 1 8 1 5 4 1 30 30 1 2 1 9 20 52 80 24 1 3 78 1 1 1 8 1 1 '120 144 7 1 49 1 5 26 1 9 1 5 4 3 3 1 34 1 3 2 1 24 52 72 24 — 88 — 1 9 1 2 '134 16 8 85 54 1 6 2 7 20 1 6 4 1 34 33 13 24 29 60 66 30 — 82 — 1 9 1 4 '134 168 85 56 18 26 20 1 6 4 7 36 36 1 5 24 26 57 72 26 1 3 72 — 1 9 1 3 '136 168 85 58 22 24 20 1 5 4 4 33 33 1 3 22 24 62 — 28 1 1 80 1 4 1 9 1 4 '17,8 22 1 107 75 2 7 32 24 1 8 57 4 5 45 1 6 34 38 72 1 32 — 1 1 23 26 23 '179 22 2 112 73 26 29 2 4 1 7 57 42 4 5 1 7 3 1 32 80 80 028 1 3 1 1 — 28 22 '18 4 229 11 6 7 2 1 30 2 5 1 9 59 43 49 1 8 32 37 70 096 36 1 4 1 1 2 1 — 1 9 '184 23 110 72 1 8 34 2 7 1 8 57 4 4 52 1 8 34 37 70 70 34 1 3 1 1 27 30 26 '186 21 1 120 80 2 7 34 26 19 58 43 48 1 8 34 34 88 72 24 1 3 1 1 — 26 — '198 24 6 120 82 28 33 28 2 1 64 46 52 1 8 3 1 36 82 — 36 1 3 1 2 — 26 22 '20 3 25 3 128 84 28 40 28 20 62 4 7 53 1 8 ^ 4 1 90 80 34 1 3 1 2 — 30 20 '21 6 26 4 130 84 2 5 40 28 20 7 1 52 57 20 — 40 86 — 14 — 1 2 — 32 30 '22 1 26 4 142 89 30 4 2 30 1 9 72 53 59 20 34 44 98 0,72 26 — 1 4 28 32 27 '22 2 27 7 146 93 30 4 2 30 1 9 67 5 1 59 20 42 4 4 10 7 0,46 32 — 1 3 26 3 1 3 1 '22 4 27 7 134 8,4 26 38 3 1 20 72 56 60 20 4 1 48 88 — 44 1 1 1 3 30 32 32 '23 8 29 1 157 94 3 1 4 3 2 9 1 9 72 52 64 22 39 43 107 40 30 — 1 2 28 34 — '41 6 49 8 26 2 165 4 4 70 57 22 11 8 88 70 34 56 72 166 18 — 042 2 1 49 6 1 64 '136 4 169 86 51 8 140 26 7 183 6 7 44 323 37 6 120 197 30 53 8 16 — 13 57 174 20 7 270 = 183 219 118 1 68 1 180 35 8 18 9 11 2 633 494 48 4 18,0 28 2 429 74,5 — — 0,32 7,0 276 31,0 310 'Usually third or founh m 'Usually mtdfin ^The second spine *Not formed ^Forming 'Transforming 'Pelagic juvenile 'Bentfiic juvenile larvae. fittfi or sixth in juveniles rather long, averaging 24-269!^ SL during the pelagic period. Depth of the pectoral fin decreases from 12''f in flexion larvae to 97? in benthic juveniles. Pelvic fin spines and developing rays are visible on the 7.7 mm larva. The adult complement of I, 5 is countable on the smallest postflexion larva, 8.8 mm. The relative length of the pelvic fin increases from 14 to 23'7r^ SL with development. The pelvic spine, always shorter than the pelvic fin rays, in- creases from 8% SL in flexion larvae to IS'/r in transforming larvae and then decreases to 15'% in benthic juveniles. The adult complement of 8 + 7 principal caudal fin rays can be counted on the 7.7 mm preflexion larva. Flexion is completed by 8.8 mm. Superior and inferior secondary caudal rays on two stained juveniles 22.4 and 23.8 mm long, were 12 + 12 and 11 + 11, respectively. Bases of dorsal and anal fin spines and rays are visible on the 7.7 mm larva. Rays and spines (in- cluding "prespines"! are fully formed by 9.9 mm and the adult complements can be counted. "Pre- 34 spines" become spines in specimens >19 mm. The longest dorsal spine increases from 19% HL in postflexion larvae to 377f in benthic juveniles. The longest dorsal ray, always longer than the longest dorsal spine, increases from 23 to 43*^7^ HL during development. The longest anal spine increases from 16 to 49^r HL. Spination iTables 4, 12). — Spines on the left side of the head of the smallest S. helvomaculatus (1.1 mm) include the parietal; first and third anterior preopercular spines; second, third, and fourth posterior preopercular spines; postocular; pterotic; inferior posttemporal; and first spine of the superior infraorbital series. The parietal spine and ridge are deeply serrated in larvae and pelagic juveniles, but the serrations are no longer visible by 41.6 mm. The parietal spine is very long in flexion larvae, averaging 27'^ HL. Its length decreases with development to 3% HL in benthic juveniles. The much smaller nuchal spine, which appears by 8 mm, averages 29f HL in flexion larvae and increases to 4 or 5'S in postflex- RICHARDSON and LAROCHE; DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Table 12.- -Development of spines in the head region o(Sebastes helvomaculatus larvae and juveniles. Specimens above dashed line are undergoing notochord flexion. + denotes spine present and - denotes spme absent. Standard length (mm) Panetal Nuchal Preopercular ' (anlenof series) Preopercular (posterior series) Opercular Superior Inferior Inler- oper- cular Sub- oper- cular Pre- ocular Supra- ocular Post- 1st 2d 3d 1st 2d 3d 4lh 5th ocular 7 7 80 8.0 + — + + + — + + - + + — + - + + + + + - - - - - - + 8.8 9.9 10.9 '12.0 '12.0 '13.4 '13.4 '13.6 '17.8 '17.9 '18.4 '18.4 '18.6 =19.8 '20.3 321.6 322.1 322.2 322.4 323.8 341.6 '136-4 '183 + + + + + + + + Table 12.— Continued. Infraorbitals Nasal Coronal Tympanic Plerotic Posttemporal Superior Inferior ^'Cr^:.' Superior Supra- (mm) 1st 2d 3d 1st 2d 3d 4th cleithral Cleithral 77 80 80 - + - - + - - + - - - - - - + - - + - - + - + - + - + - 9.9 10.9 '12.0 '12.0 '13.4 '13.4 '13.6 '17.8 '17.9 '18.4 '18.4 '18.6 319.8 320.3 321.6 322.1 322.2 322.4 323.8 341.6 '136.4 '183 I}) I}) -(') (') 'Transforming ^Bump indicating beginning of spine formation ^Pelagic juvenile 'Benttiic juvenile ion, transforming, and pelagic juvenile stages. The nuchal and parietal spines are fused together by the time juveniles are 42 mm long. The posterior preopercular spine series is prom- inent in S. helvomaculatus larvae. The third spine of the series is weakly serrated in larvae >8 mm up to pelagic juveniles. It is relatively long in larvae averaging 27 to 31'7f HL in flexion and postflexion stages. Its length decreases to 2'7f in benthic juveniles when it is no longer serrated. 35 FISHERY BULLETIN VOL, 77. NO, 1 Very weak serrations appear on the second and fourth posterior preopercular spines of most larger larvae and smaller pelagic juveniles. All five pos- terior preopercular spines are present on speci- mens >8.0 mm. The first and third anterior preopercular spines seen on the smallest larva are no longer visible on specimens >23 mm. The sec- ond anterior preopercular spine never develops. The superior and inferior opercular spines are present on all specimens >8 mm. The interopercu- lar spine is present at 8.8 mm and persists into benthic juveniles. The subopercular spine is pres- ent just above the interopercular spine on the largest benthic juvenile, 183 mm. The supraocular ridge and the anterior margin of the postocular spine are serrated on specimens up to 23.8 mm. The preocular and supraocular spines are first seen as bumps in a 13.4 mm speci- men. Serrations are present on the supraocular spine but disappear along with those on the su- praocular ridge on larger pelagic juveniles. The first superior infraorbital spine is visible up to 23 mm. The second superior infraorbital spine appears on specimens 12 to 23 mm. The fourth superior infraorbital spine is present on larvae >8 mm and the third superior infraorbital spine is present on larvae >13.4 mm. The third and fourth spines both disappear by 23 mm. The first and second spines of the inferior infraorbital series are present on all specimens >8 mm but appear only as blunt projections on benthic juveniles. The third inferior infraorbital spine never develops. The nasal spine appears as a bump by 9 mm and becomes strong and sharp during the larval period. The tympanic spine develops by 41.6 mm and appears as a strong sharp spine on benthic juveniles. The pterotic spine is present on all specimens >41.6 mm. The inferior posttemporal spine is present on all specimens examined but is minute on the two benthic juveniles, 136 and 183 mm, and probably disappears in larger specimens. The supracleithral spine is present on all speci- mens >8.0 mm. The superior posttemporal ap- pears at 13.4 mm and is present on all larger specimens. Posterior to the opercle the cleithral spine appears on all specimens >19 mm. Scale Formation. — Lateral line pores first appear anteriorly and are visible on specimens >17 mm. Scale formation begins on pelagic juveniles >23 mm. Pigmentation. — The smallest larva of S. hel- vomaculatus, 7.7 mm (similar to the 8.0 mm specimen illustrated), has pigment on the head over the brain. Melanophores line the inner tip of the lower jaw. In the abdominal region, an inter- nal melanistic shield is present over the dorsolat- eral surface of the gut. No other pigment is visible on the body. The pectoral and pelvic fins are fringed with expanded and fused melanophores and have a light scattering of more contracted, elongate melanophores on the fin blades. Both inner and outer pectoral fin base surfaces are un- pigmented. During larval development, pigment over the brain becomes obscured. At 13.4 mm pigment in- side the lower jaw disappears. Specimens >17 mm develop two to six internal melanophores dorsally on the opercle. During the transformation period, 12.0 to 18.6 mm, two or three melanophores may appear just posterior to the orbit on specimens >18 mm. In- ternal gut pigment increases ventrolaterally reaching the ventral surface of the gut by 17.9 mm. The anterior margin of the cleithrum is usu- ally unpigmented. A patch of 9 to 10 large stellate melanophores appears laterally on the caudal peduncle at 12.0 mm at the beginning of the trans- formation period. Melanophores are added to this patch until it extends to the dorsal body surface at = 18 mm. Melanophores in this patch often appear expanded and fused. The pectoral and pelvic fins remain fringed with pigment although this may not be obvious if the fins are frayed. The number of melanophores on the fin blades generally de- creases. During the pelagic juvenile period, 19.8 to 41.6 mm. pigment appears over the head surface, snout, and upper lip of specimens "^22 mm. Melanophores are added along the posteroventral margin of the orbit and a patch of melanophores appears just dorsal to the first superior infraor- bital spine. The internal pigment patch on the operculum remains distinguishable. Internal gut pigment becomes increasingly obscured by muscu- lature. A single saddle of melanophores develops on the dorsal surface of the body over the nape and beneath the spinous dorsal fin anterior to dorsal spine XI. The first melanophores generally appear there at the onset of the pelagic juvenile stage, although a few may develop earlier. This saddle extends ventrolaterally from the nape to the vicin- ity of the supracleithral spine and from the spi- nous dorsal fin halfway to the lateral line by 22 36 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES mm. By 41.6 mm small external melanophores cover all but the ventralmost one-fourth of the abdominal region including most of the pectoral fin base and the dorsal one-fourth of the gut re- gion. The dorsal saddle and internal gut pigmen- tation still appear as more darkly pigmented areas. The caudal peduncle patch expands to the dorsal and ventral body margins. Specimens >20 mm have a few melanophores extending an- teriorly from the peduncle patch along the dorsal body margin under the posteriormost dorsal rays. By 41.6 mm the entire tail region of the body is also covered with small external melanophores, although the caudal peduncle patch and dorsal midline melanophores remain visible. Pectoral and pelvic fins lose all pigment by 41.6 mm, except for a patch of small melanophores on the base of the central pectoral rays. The spinous dorsal fin becomes completely covered with small melano- phores by 41.6 mm and small melanophores cover the proximal one-fourth of the soft dorsal fin. Small melanophores extend onto the bases of the caudal fin rays by 41.6 mm. Melanistic pigment is inconspicuous on the benthic juveniles examined. 136 and 183 mm. The caudal peduncle pigment patch is no longer visi- ble. Occurrence (Figures 14, 15). — Sebastes hel- vomaculatus ranges from Coronado Bank, off San Diego, Calif, to Albatross Bank, Gulf of Alaska, and occurs in depths from 133 to 456 m (Chen 1971). It is apparently primarily a deepwater species judging by some of the older common names given to it, "deep-water scacciatale" and "deep-water scratch-tail" (Phillips 1957). The largest numbers and smallest larvae were taken 83 and 120 km off Newport beyond the continental shelf break. Most pelagic juveniles were taken at the same locations as the larvae, probably reflect- ing the increased sampling effort in that area. One benthic juvenile, 136 mm, was taken in an otter trawl at a depth of 370 m (lat. 44°47.9' N, long. 124°40.9' W). A second juvenile, 183 mm, was col- lected after a seismic profiling explosion on Stonewall Bank ( =lat. 44°30' N, long. 124°25' W). JUL I 1 1 ihX- AU6 J. X-L SEP OCT NOV JlL -4- 20 to 60 80 100 120 140 180 190 Standard Length (mm) Figure 15. — Seasonal occurrence of larvae and juveniles of Sebastes helvomaculatus off Oregon, Data from 1961 to 1976 combined. Dashed line separates pelagic and benthic stages. ' ' ' 1^^- , w--^-^- '• )"-" - ■^ - '. '. i .' L^. \ 1 - i Jl' A „, Pelagic Juveniles ]• , , "^r-. FIGURE 14. — Number of specimens and location of capture of larvae and juveniles of Se6as^es helvomaculatus off Oregon (1961-76) described in this paper. 37 FISHERY BULLETIN: VOL, 77, NO, 1 Based on examination of gonads, Westrheim (1975) reported that parturition of S. hel- vomaculatus takes place primarily in June from Oregon to British Columbia. We took small larvae >10 mm only in July and August. Pelagic juveniles were captured in August, September, and November. The two benthic juveniles were taken in July. Adults of S. helvomaculatux are uncommon in Oregon trawl landings iNiska 1976). They ranked 9th and 16th in biomass in trawl surveys on the Oregon continental shelf and 8th on the continen- tal slope together with S. elongatus and S. zacen- triis (Demory et al. 1976). Larvae and juveniles were not common in our collections. COMPARISONS (TABLE 13) Prior to this paper, developmental series of 7 of the 69 northeast Pacific (including the Gulf of Cal- ifornia) species of Sehastes had been described: S. cortezi, S. sp. Gulf Type A, S. jordani, S. levis, S. macdonaldi , S. melanostomus , and S. paucispinis (Moser 1967, 1972; Moser et al. 1977; Moser and Ahlstrom 1978). While pelagic stages of these species exhibit some similarities to the three de- scribed by us, they also differ in a number of characters. The most notable of these are discus- sed here in a comparative sense. Flexion and postlarvae of S. pinniger are quite deep bodied (38-40/f SL) although body depth at the pectoral fin base decreases considerably (33'7f SL) by the pelagic juvenile stage. Larvae and juveniles of S. melanostomus are also deep bodied. Pelagic stages of S. Jordani are comparatively slender (17-24'7< SL). Prior to completion of notochord flexion, S. paucispinis is also relatively slender bodied. Pelagic stages of S. crameri, S. he/vomaculatus. S. levis. and S. macdonaldi are somewhat intermediate in body depth. Snout to TABLE13, — Morphometric comparison of larvae and juveniles of nine species ofSebastes from the northeast Pacific. Values are mean percentages of body proportions related to standard length (SL) or head length SL: Preflexion — — — — — — 4 — — — Flexion 7 _ 14 1 6 6 12 14 14 Postflexion 15 16 17 Transforming _ 21 _ 19 9 21 14 16 35 23 Pelagic juvenile — 21 _ 19 14 24 22 20 25 22 Benthic juvenile _ 21 _ 23 -_ _ _ — _ 21 Parietal spine length HL: Preflexion — — Flexion 6 27 24 Postflexon 2r-22 7 25-34 18 20-23 20 Transforming 6 13 10 Pelagic juvenile — 3 — 6 _ _ _ — _ 7 Benthic juvenile 3 Preopercular spine lengtti HL: Preflexion — — — — — — — — — — Flexion 18 27 34 Postllexion 17 _ 31 _ _ 35 _ 32 Transforming _ 18 — 20 — _ — — — 24 Pelagic juvenile _ 12 _ 12 — _ _ — _ 13 Benthic juvenile - 7 - 2 — — — — — 5 'Values from Ivloser et al, (1977) and Moser and Ahlstrom (1978) 38 RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES anus distance is markedly shorter in larvae and juveniles oCS.jordaiii (36-53'^< SL) compared with the other species. The pectoral fins in S.jordani remain compara- tively short (7-22% SL) during pelagic develop- ment while those of S. levis attain an exceptional size (to 45'7( SL). Late larval stages of S. pauci- spinis also have outstandingly long pectoral fins (36'"f SL). Fin lengths among the other species are intermediate by comparison and vary to a lesser degree during development. The pelvic fins of S. pauc7spi>!ii' also become extraordinarily long (35'> SL) during the late larval period whereas those of S.jordani remain relatively short. Parietal spine length varies among species with the largest spines appearing in early larvae of S. helvornacu/atus {279i HL) and S. sp. Gulf Type A (25-349f HL). This spine is noticeablely short on S. cramen (3-7% HL) during the entire pelagic phase. The third preopercular spine is outstand- ingly long on early larvae of S. macdonaldi (35% HL) and S. pinniger (34% HL) but is compara- tively short on S. cramen (17% HL) as is the parietal. Pigmentation on the paired fins varies from the unpigmented condition in S.jordani to the heavily pigmented fins of S. macdonaldi and S. crameri. The pectoral fins of S. cortezi are pigmented at the fin base but not the outer margin, while pigment is primarily concentrated on the outer margin of the fins in S. paucispinis, S. levis, and S. helvomacu- latu.s at least during the early pelagic period. Pec- toral fins of S. pinniger, S. melanostomus, and S. sp. Gulf Type A are lightly pigmented. General body pigmentation differs among the species considered. Larvae of S. pinniger have a '•haracteristic lack of body pigment. A patch of uape pigment develops early in S. crameri and S. macdonaldi. appearing more pronounced in the former species. Postflexion larvae of both S. cram- eri and S. macdonaldi develop pigment on the entire spinous dorsal fin. A characteristic black blotch develops on the posterior portion of the first dorsal fin in pelagic juveniles of S. pinniger. Lar- vae of S. melanostomu.'i, S. paucispini.'i, and S. macdonaldi have a characteristically low number of ventral midline melanophores, 4 to 11 (mean 8), 6 to 14 (mean 9), and 6 to 14 (mean 8), respectively. A patch ofpigment forms on the caudal peduncle of S. helvomaculatus , S . paucispinis, S.jordani, and S. cortezi. The form of the patch varies with the species and is most pronounced in S. hel- vomaculatus. One characteristic melanophore ap- pears at the base of the caudal fin in S. cortezi, while melanophores form a line ofpigment at the base of the caudal fin in S.jordani, but not in any of the other species. Pelagic juveniles of S. helvomaculatus develop only one melanistic pigment saddle beneath the spinous dorsal fin. Five distinct saddles form on S. macdonaldi, S. crameri, S. levis, S. paucispinis, and S. pinniger in comparable locations on the body although a more blotchy pattern develops on S. pinniger. On S. melanostomus, three pro- nounced melanistic bars develop on the body. Ap- parently no obvious saddles or bars develop on pelagic juveniles of S. jordani or S. cortezi. These comparisons together with distinguish- ing features of each species given by us, Moser (1972), Moser et al. (1977), and Moser and Ahlstrom (1978), and range of occurrence should aid in identification of all but the smallest larvae. As additional species are described, such compari- sons may also provide insight into relationships within the genus Sebastes. ACKNOWLEDGMENTS We thank H. Geoffrey Moser for helpful advice and for the use of unpublished data on color pat- tern in a livejuvenile of S. crameri. Stuart G. Poss offered useful advice on head spine terminology. During the course of this study the following people provided helpful information on Sebastes spp.: Carl Bond, Jerry Butler, William N. Esch- meyer, Colin Harris, Michael Hosie, Andy Lamb, Bruce M. Leaman, Alex E. Peden. Jay C. Quast, David Stein, Arthur D. Welander, Sigurd J. Wes- trheim, Norman J. Wilimovsky. Range Bayer, Robert A. Behrstock, Carl Bond, Jerry Butler, Colin Harris, Michael Hosie, Robert Lea, Law- rence Moulton. and Alex Peden provided addi- tional specimens of Sebastes to examine. Special thanks are extended to William G. Pearcy for al- lowing us to use his extensive midwater trawl collections from waters off Oregon. Lo-Chai Chen, H. Geoffrey Moser, Stuart G. Poss, and Sigurd J. Westrheim reviewed an earlier draft of the man- uscript. This research was supported by a 1-yr ( 16 June 1976-15 June 1977) contract No. 03-6-208- 35343. LITERATURE CITED AHLSTROM. E. H. 1961. Distribution and relative abundance of rockfish 39 FISHERY BULLETIN; VOL 77. NO 1 {Sebastodes spp.) larvae off California and Baja Califor- nia. Rapp. P-V. Reun, Cons. Int. Explor. Mer 150:169- 176. 1965, Kinds and abundance offi.'shes in the California Cur- rent region based on egg and larval surveys. Calif Coop Oceanic Fish, Invest, Rep. 10:31-52. Bailey, R. M., J. E. Fitch, E. S. Her.ald. E. a. Lachner, C. C. LINDSEV. C. R. ROBINS, AND W. B. SCOTf. 1970, A list of common and scientific names of fishes from the United States and Canada, Am. Fish. Soc. Spec. Publ. 6, 149 p BARSLIKOV, V, V. 1973, A systematic analysis of the group Sebastex waki- yai-S. paradoxus-S. steindachneri. Communication 2 (containing a redescription of .S. wakiyan. J Ichthyol, (Engl, Transl, Vopr. Ikhtiol.l 13:824-833, Chen, L.-C. 1971, Systematics, variation, distribution, and biology of rockfishes of the subgenus Sfhastomus (Pisces, Scor- paenidae,Sefca,s(e.<;). Bull, ScrippsInst,Oceanogr,,Univ, Calif, 18, 115 p. 1975, The rockfishes. genus Sebaxtes (Scorpaenidae), of the Gulf of California, including three new species, with a discussion of their origin. Proc. Calif Acad. Sci. 40:109- 141. DeLacy, A. C, C. R, Hit/., and R. L, Dryfoo.s, 1964. Maturation, gestation, and birth of rockfish iSebas- todes) from Washington and adjacent waters. Wash. Dep. Fish., Fish. Res. Pap. 2(31:51-67. Demory, R. L., M. J. HosiE, N. Ten Eyck, and B. O, FORSBERG. 1976. Marine resource surveys on the continental shelf off Oregon, 1971-74. Oreg. Dep. Fish. Wildl,, Completion Rep.. July 1, 1971 to June 30, 1975, 49 p. EFREMENKO, V. N., AND L. A, LiSOVENKO. 1970, Morphological features of intraovarian and pelagic larvae of some Sebastotles species inhabiting the Gulf of Alaska. In P. A. Moiseev (editor), Soviet fisheries inves- tigations in the northeast Pacific. Part V, p, 267-286, (Transl, Isr, Program Sci, Transl,; available Clearing- house Fed, Sci, Tech, Inf, Springfield, Va,, as TT71- 50127), EIGENMANN, C, H, 1892, The fishes of San Diego. California, Proc, U.S. Natl, Mus, 15:123-178. FOLLETT, W. I., AND D. G. AINLEV. 1976. Fishes collected by pigeon guillemots, Cepphus co- luniba (Pallas), nesting on Southeast Farallon Island, California. Calif Fish Game 62:28-31, Hart, J, L, 1973. Pacific fishes of Canada. Fish, Res. Board Can. Bull, 180, 740 p. Lea, R, N,, and J. E. Fitch. 1972, Sebastes rufinanus, a new scorpaenid fish from Califomian waters, Copeia 1972:423-427, Matsubara, K, 1943. Studies on the scorpaenoid fishes of Japan, Anat- omy, phylogeny and taxonomy 1 and II, Trans, Sigen- kagaku Kenkvusyo, Tokyo, 486 p, MERKEL, T. J. 1957. Food habits of the king salmon, Oncorhynchus tshawytscha i Walbaum), in the vicinity of San Francisco, California, Calif Fish Game 43:249-270, Miller, d. j,, .\nd r, n, lea. 1972. Guide to the coastal marine fishes of California. 40 Calif Dep, Fish Game, Fish Bull 157, 235 p, Morris, R, W, 1956. Early larvae of four species of rockfish, Sebastodes. Calif Fish Game 42:149-153, MO.SER, H, G, 1967, Reproduction and development of Sebastodes paucispinis and comparison with other rockfishes off southern California. Copeia 1967:773-797, 1972, Development and geographic distribution of the rockfish, Sebastes macdonaldi (Eigenmann and Beeson, 1893), family Scorpaenidae, off southern California and Baja California. Fish, Bull,, US, 70:941-958. M(.)SER, H. G., E, H, AHLSTROM, AND E. M, SANDKNOI', 1977, Guide to the identification of scorpionfish larvae (family Scorpaenidae) in the eastern Pacific with com- parative notes on species ofSebafttes and Helicolenus from other oceans. U.S. Dep, Commer., NOAA Tech, Rep, NMFS Circ, 402, 71 p, MOSER, H. G., AND E. H. AHUSTROM. 1978. Larvae and pelagic juveniles of blackgill rockfish, Sebastes melanostomus, taken in midwater trawls off southern California and Baja California. J. Fish. Res. Board Can, 35:981-996, NISKA, E, L, 1976, Species composition of rockfish in catches by Oregon trawlers 1963-71. Oreg. Dep Fish, Wildl, Inf Rep, 76-7, 80 p. PACIFIC Marine Fisheries Commission. 1964-1976. Data series: Bottom or trawl fish section. Pac. Mar. Fish. Comm., Portland, Oreg., p, 1-472, 500-510, Phillips, J. B. 1957 A review of the rockfishes of California (family Scor- paenidae), Calif Dep, Fish Game, Fish Bull 104, 158 p, 1964, Life history studies on ten species of rockfish (genus Sebastodes). Calif. Dep. Fish Game, Fish Bull. 126, 70p Powell, D, E., D, L. Alverson, and R, Livincstone, Jr. 1952, North Pacific albacore tuna exploration — 1950, U.S. Fish Wildl, Serv,, Fish, Leafl, 402, 56 p. i] PRITCHARD, A. L., AND A. L, TESTER, 1944. Food of spring and coho salmon in British Colum- bia. Fish. Res. Board Can Bull 65. 23 p. QUAST, J. C, AND E. L, Hall, 1972. List of fishes of Alaska and adjacent waters with a guide to some of their literature. U.S. Dep. Commer., NOAA Tech. Rep, NMFS SSRF-658, 47 p. Richardson. S. L. 1977, Larval fishes in ocean waters off Yaquina Bay. Ore- gon: abundance, distribution and seasonality January 1971 to August 1972. Oreg, State Univ, Sea Grant Coll, Prog, Publ, ORESU-T-77-003, 73 p. Richardson, S. L.. and W, G, Pearcy, 1977. Coastal and oceanic fish larvae in an area of up- welling off Yaquina Bay. Oregon, Fish, Bull., US 75:125-145, Rosenblatt, R. H., and L.-C. Chen. 1972. The identity o{ Sebastes babcocki and Sebastes rub- rivmclus. Calif Fish Game 58:32-36, SILLIMAN, R, P, 1941. Fluctuations in the diet of the chinook and silver salmons iOncorhynchus tsckawytscha and O. kisutch ) off Washington, as related to the troll catch of salm- on. Copeia 1941:80-87. SNVTKO, V, A,, AND N, S, FADEEV, 1974. Data on distribution of some species of sea perches along the Pacific coast of North America during the sum- RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES mer - autumn season. Doc. Subm. Canada-USSR Meet, on Fish, in Moscow-Batumi, USSR, November 1974, 14 p. iTransl. 3436, Can. Transl. Ser.l Taylor, W. R. 1967. An enzyme method of clearing and staining small vertebrates. E>roc. US. Natl. Mas. 122(3596), 17 p. VerHOEVEN, L, a. (editori. 1976. 28th annual report of the Pacific Marine Fisheries Commission for the year 1975. Pac. Mar. Fish. Comm., Portland, Oreg., 46 p. Waldron, K. D. 1968. Early larvae of the canary rockfish.Setastorfespm- niger. J. Fish. Res. Board Can. 25:801-803. Wales, J. H. 1952. Life history of the blue rocklish, Sebastodes mys- tinus. Calif. Fish Game 38:485-498, Weitzman,S. H. 1962. The osteology of Brycon meeki. a generalized characid fish, with an osteological definition of the fami- ly. Stanford Ichthyol. Bull. 8(1), 77 p. WESTRHEIM, S. J. 1966. Northern range extensions for three species of rockhsh iSebastesflai'idus.S.pauctspinis andS.ptnniger) in the North Pacific Ocean. J. Fish. Res. Board Can. 23:1469-1471. 1975. Reproduction, maturation, and identification of lar- vae of some Sehastes iScorpaenidae) species in the north- east Pacific Ocean. J, Fish Res. Board Can. 32:2399- 2411. WESTRHEIM, S. J., AND H. TSUYUKI. 1967. Sebastodes reedi, a new scorpaenid fish in the north- east Pacific Ocean. J. Fish. Res. Board Can. 24:1945- 1954 1972. Synonymy of Sebastes caenaematicus with Sebastes borealis, and range extension record. J. Fish. Res. Board Can. 29:606-607. WHITNEY, J. P. 1893. Salmon in salt water Forest Stream 41:120-121. YOUNG, P. H, 1969. The California partyboat fishery 1947-1967. Calif Dep. Fish Game, Fish Bull. 145, 91 p. 41 FISHERY BULLETIN VOL 77. NO 1 APPENDIX Table l. — Ranges of eastern North Pacific species ofSehastes.' This Hst does not include one new species being described by Lea and Fitch (Chen 1975). Asterisk indicates species in the subgenus Sehastomus. o o — 3 ^ Species Southern range limit O 5 Northern range limit S aleutianus S alutus S atrovirens S aunculatus S aurora S babcocki S borealis S brevispmis S camatus 'S caunnus^ S chlorostictus S chrysomelas S ciliatus 'S constellatus S cortezi S cramen S dalli S diploproa S elongaius S emphaeus 'S ensifer S eniomelas 'S eos 'S exsul S fiavidus S gilli S goodei "S helvomaculatus S hopkinsi S lordani "S lentiginosus S lews S macdonaldi S maliger S melanops S melanostomus S mtniatus S mystinus S nebulosus S nigrocinctus 'S notius S ovaJis S paucispinis S pendunculans S phillipsi S pinniger S polyspinis S pronger S rastrelliger S reedi "S rosaceus "S rosenblaW S rubernmus rubnvtnctus '■ rufinanus rufus saxicola semicinctus serranoides sernceps Simulator sinensis spinorbis umbrosus variegatus varispinis ' wilsoni zacentrus Monterey. Calif La Jolla, Caht Pt San Pablo, Ba)a Hipolilo Bay, Baja San Drego, Calif San Diego, Calif Eureka, Calif Santa Barbara I , Calif San Rogue, Baja San Benito I . Baja Cedros I , Baja Natividad I . Baia Dixon Entrance, B C Thetis Bank. Baja Gult ot Calif Santa Catalina 1 . Calif Sebastian Viscaino Bay, Baja San Martin I , Baja Cedros I . Baja Punta Gorda, Calif ^ Ranger Bank, Ba/a Todos Santos Bay. Baja Sebastian Viscamo Bay, Baja Gult of Calif San Diego, Calif Ensenada, Baja Magdalena Bay, Baja Coronado Bank, Calif Guadalupe I . 6a|a Cape Coinetl, Baja Los Coronados I . Baja Ranger Bank. Baja Gulf of Calif Pi Sur, Calif Paradise Cove, Baja Cedros I , Baja San Benilo I , Baja Pt Santo Tomas. Baja San Miguel I , Baja Pt Buchon, Baja Uncle Sam Bank. Baja Cape Coinetl. Baja Pt Blanco, Baia Gulf of Calif Newport. Calil Cape Coinetl, Baja S E Alaska San Diego, Calif Playa Mario Bay. Baja Crecent City, Calif Turtle Bay. Baja Ranger Bank, Baja Ensenada. Baja Cape Colnett, Baja San Clemenli I , Calif Guadalupe I , Baja Sebastian Viscamo Bay, Baja Sebastian Viscamo Bay Baja San Benito I , Baja Cedros I , Baja Guadalupe I . Baja Gulf of Calif Gulf of Calif Pt San Juanico, Baja Queen Charlotte Sd . B C Gull of Calif Cortez Bank, Calif San Diego, Calif Aleutians and Japan Bering Sea and Japan Timber Cove, Sonoma Co , Calif S E Alaska Amphndile Pt , Vancouver I , 8 C Amchilka I , Alaska S E Kamchatka Bering Sea Eureka, Calif Gult of Alaska Copalis Head. Wash Eureka. Caht Benng Sea San Francisco. Calif Gult of Calif Bering Sea San Francisco. Calif Alaska Peninsula Green I , Montague I , Gult of Alaska Kenai Peninsula, Gult ot Alaska San Francisco. Calif Kodiak. Alaska San Francisco. Calit [''Wash) Gult of Calif Kodiak. Alaska Monterey. Calif Cape Scott. Vancouver I . B C Albatross Bank. Gulf of Alaska Farallon 1 . Calif Le Perouse Bank, Vancouver I . B C Santa Catalina I , Calif Usal. Mendicino Co . Calif Pt Sur. Calif Gult of Alaska Amchitka I , Alaska Wash ^Bering Sea) Vancouver I , B C BC (''Bering Sea) S E Alaska S E Alaska Guadalupe I . Baja San Francisco. Calif Kodiak. Alaska Gult ot Calif Monterey Bay. Calif. S E Alaska Eastern Kamchatka Bering Sea Yaquina Bay. Oreg Sitka, Alaska San Francisco, Calif CPuget Sd , Wash ) Avila, Calif CSan Francisco. Calif ) Gulf ot Alaska San Francisco. Calif San Clementi I . Calif Mad River. Calif S E Alaska PI Pinos. Monterey Co . Calif Redding Rock, Del None Co . Calif San Francisco. Calif San Pedro, Calif CPt Conception. Calif ) Gulf of Calft Gulf of Calif Pt Conception, Calif Unimak Pass, Aleutian I Gult of Calif S E Alaska Sanak 1 , Aleutians 'Compiled from Bailey etal ( 1970), Chen (1971). Lea and Filch (1972), Miller and Lea (1972), Ouast and Hall (1972). Rosenblatt and Chen (1972), Barsukov (1973), Hart (1973), and Chen (1975), and original data for S emphaeus No records from ttie Sea of Okhotsk ^Includes S vexiiiaris (Chen 1975. W N Eschmeyer. Senior Curator tor Research, California Academy of Sciences. Golden Gate Park. San Francisco. CA 941 18, pers commun November 1976) ^Based on data obtained dunng this study 42 RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES Appendix Table 2. — Chart showing interorbital curvature and presence or absence of the supraocu- lar spine for rockiishes [Sebastes spp.) occurring off Oregon.' x indicates usual condition; o indicates occasional occurrence. Inlerorbital Interorbital Flat-convex Concave Flat-convex Concave Supraocular spine Supraocular spine Species Present Absent Present Absent Supraocular spine Supraocular spine Species Present Absent Present Absent S- aleutianus S. alutus S. aunculatus S. aurora S. babcocki S. borealis S. brevispinis S. caunnus S. chlorosticlus S cramen S. diploproa S. elongatus S. emphaeus S. entomelas S. eos^ S. flavidus S goodei S. helvomaculatus S. lordani S maliger S melanops S melanostomus S miniatus S mystinus S nebulosus S nigrocinctus S paucispinis S pinniger S pronger S rastrelliger S reedi S rosaceus^ S ruberrimus S saxicola S wilsoni S- zacenlrus ' Compiled from Phillips ( 1 957) , Westrheim and Tsuyuki ( 1 967. and original data for S emphaeus ^Species may be rare off Oregon 1972). Chen (1971). Miller and Lea (1972). and Hart (1973). APPENDIX Table 3. — Numbers of dorsal, anal, and pectoral fin soft rays for rockiishes iSebastes spp.) occurring off Oregon.' x indicates usual numbers, o indicates occasional occurence. Species Dorsal fin rays Anal fin rays Pecloral fm rays 11 12 13 14 15 16 17 5 10 11 15 16 17 18 19 20 21 22 S aleutianus S alulus S aunculatus S aurora S babcocki S borealis S brevispinis S caunnus S chlorostictus S cramen S diploproa S elongatus S emphaeus S entomelas S eos^ S tiavidus S goodei S helvomaculatus S lordani S maliger melanops melanostomus miniatus mystinus nebulosus nigrocinctus paucispinis pinniger pronger S rastrelliger S reedi S rosaceus^ S ruberrimus S saxicola S wilsoni S zacentrus 'Compiled from Phillips (1957). Westrheim (1966), Westrheim and Tsuyuki (1967. 1972). Chen (1971). Miller and Lea (1972). and Hart (1973), and onginal data for S emphaeus ^Species may be rare off Oregon 43 FISHERY BULLETIN: VOL 77. NO 1 Appendix Table 4. — Total numbers of gill rakers on first gill arch for rockfishes(Se6as/esspp.) occurring off Oregon.* Species 22 23 24 25 26 27 26 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 S aleutianus x x x x x x S alutus xxxxxxxxx S auriculatus x x x x x x S aurora x x x x x S babcocki x x x x x S borealis x x x x x S brevispinis x x x x S caurmus x x x x x x x S. chlorostictus x x x x x x S crameri x x x x x x S diplopora X X X X X X S elongatus x x x x x x S emphaeus x x x x x x x S entomelas x x x x S eos' X X X X X X S flavidus X X X X X X X S goodei x x x x x x S helvomaculatus x x x x x x S jordani x x x x x x x S. maliger x x x x x S melanops x x x x x x x S rnelariostomus xxxxxxxxx S miniatus xxxxx xxxx S mysf/nus x x x x x x S nebulosus x x x x x x S nigrocinctus xxxxx S paucispmis xxxx S. pinntger x x x x x x S. proriger xxxx xxxx S. rastrelliger xxxx S reed/ x x x x x x x S fosaceus^ x x x x x x S rubemmus x x x x x x S. saxicola xxxxx S wilsoni XX xxxx S zacenfrus x x x x x x x ' Compiled from Phillips ( 1957), Westrhetm and Tsuyuki( 1967. 1972), Chen (1971). Miller and Lea (1972). and Hart (1973), and original data for S empftaeus ^Species may be rare off Oregon. 44 RICHARDSON and LAROCHE DEVELOPMENT AND OCCURRENCE OF ROCKFISHES 3 1 2 O O Q 1 Q. 3 O 5 3 5 3 ra O fD £ tl ro nj -Q -Q ■Q O CO 07 W CO CO t/l C/1 1 5 O.S c o O TD QJ 0) a> o i o t ^ t o c c fe O O 0) cocoi/icocococococo (if bcittlenosed dolphins and West Indian manatees entering or leaving the Indian River during the time of the aerial surveys, indicating direction of travel relative to tidal flow Dale 11977) Bottlenosed dolphins West Indian manatees 10 Aug 1 1 Aug 12 Aug 13 Aug 14 Aug 15 Aug Total 4 adults moving against tide into river through Sebas- tian Inlet 7 adults 2 calves moving with tide trom river into Sebastian Inlet thence against tide back into river 1 adult moving against tide into river through Sebas- tian Inlet 1 luvenile milling within Sebastian Inlet at slack tide 15 individuals consisting ol 5 moving against tide 9 moving both with and against tide and i milling within inlet 2 adults milling within Fori Pierce Inlet 2 adults moving against tide into nver through Fort Pierce inlet 1 adult moving with tide from river to ocean through Sebastian Inlet 1 adult moving with tide from river to ocean through Sebastian Inlet 6 individuals, consisting ol 2 milling withm inlet 2 moving against tide, and 2 moving with tide T\HLK 4 — Summary of West Indian manatee sightings by day during the six 1-day aerial surveys. August 1977. TaHLK 5. — Some estimates of density of bottlenosed dophms, Tursiops sp., in coastal waters of the southeastern United States. Survey Total no ot Number of an mals Calves ol Other possible Date no sightings Total season calves 10 Aug 1 9 13 H7 6%) 1(0 7»„) 11 Aug 2 12 21 2(9 5%l 1(0 7%) 12 Aug 3 8 18 2(11 1%I O(-) 13 Aug 4 1 1 18 1(5 6%) Ot-) 14 Aug 5 11 41 5(12 2°^l O(-) 15 Aug 6 9 40 4(10 0°o| 3(2 O-'o) Total 60 151 15(9 9%) 5(3 3%) Reynolds'i. and were consistent with those re- ported from aerial surveys conducted in Texas using similar methodology (Barham et a!.**! (Table 5). This consistency and the relatively low var- iance estimates are evidence that this was a realistic estimate of the numbers of dolphins in the rivers during the time of the survey. Biittlenosi'd dolphins have been observed to occur as individuals and in groups of over 200 animals i Leathfruiind and Platter''). Mean herd sizes iif hdtlleno.sed dolphins off eastern P^lnrida and in {hv C!ulf of Mexico vary considi'iahiy I'nim one area to another- ('ii'oups apparently decrease 'Odell. D K.. and J, E Reynolds III In press. Distribution and abundance of the bottlenosed dolphin. Tursiitps Iruniiitus. on the west coast of'Florida. Contract Report to the U.S. Marine Mammal Commission. Wash., D.C., 5.5 p. National Technical Information Service. Wash.. DC 'Barham. E, G . J, C. Sweeny. S. Leatherwood. R. K Beggs. and C. L, Barham, 1978, Aerial census of bottlenosed dol- phins tTursifips truiicatiist in a region of the Texas coast. Un- publ- manuscr,. 34 p. Southwest Fisheries Center. National Marine Fisheries Service. NOAA. P.O, Box 271. La Jolla, CA 920.38 "Leatherwood. S,, and M. F, Platter, 1975, Aerial assess- ment of bottlenosed dolphins off Alabama. Mississippi, and Louisiana, hi D, K, Odell, D. B, Siniff. and G, H. Waring ifditorsi. 7\irsiiips tnmcaliis assessment workshop, p, 49-86, Final Report. U,S, Marine Mammal Commission, Contract MM5AC021 Dolphin Dolphins Location Reference per km^ per n mi.^ Mississippi Leatherwood et al 023 057 gull coast (1978) Louisiana Leatherwood et al 44 1 08 gulf coast (1978) Florida' Odell and Reynolds 23 57 West Coast (see footnote 7) Texas Barham et al (see 65 1 61 gull coast footnote 8) Florida This paper 0.6B 1 77 Indian River ^Derived trom their Table 10 by computing the product ol mean I (5 43) and mean herd density (0 0497) in size with distance from shore lOdell and Reynolds see footnote 7i; tend in coastal waters to be larger in deeper and in open water areas than in shallou embaymenls. lagoons, and marshlands I LeatheiuDod and Platter see footnote 9; Leath- erwood et al. 1978; Shane and Schmidley'"); and tend to fluctuate in size seasonally with little pat- tern discernible i Shane and Schmidley see foot- note lOi. The mean group size observed during this stt-id\- IS. 21 \sas well within the limits reported by all authors for eastern Florida and gulf coast v\a- ters. This and the lack olcorrelation between herd size and herd densit\' lurther suppoi't the reason- ableness of this population estimate (only if the distribution of herd sizes were normal could the inference technically lie made that the two vari- ables were independent (Figure 4ii. Because the estimation of variance in total numbers of animals assumes that herd size and '".Shane, S, H,, and D, J, Schmidley, In press. Population hiiilogy of .Atlantic bottlenosed dolphins, Tursittpti truncatus, in the .Aransas Pass area of Texas, Contract Report to the U.S. Marine .Mammal Commi.ssion. Wash,, DC. 2.'i8 p. National Technical Inform.itinn .Service. Wash., D.C. 56 LEATHERWOOD AERIAL SURVEY (IF DOLPHINS AND MANATEES herd density are mutually independent, the data by day were examined for correlation. Using Ken- dall's rank correlation coefficient (Conover 1971) at a = 0.05, mean herd size and mean herd density were demonstrated to be uncorrelated within the area surveyed. The dolphin densities per square kilometer were then multiplied by the area surveyed and a factor of 5 (since the survey covered 20' V of the total area) and the 95'^i confidence limits calculated for the estimate. The figures support an estimate of 438±127 dolphins for the Indian and Banana Riv- ers during the time of the survey. As an alternate method for estimating dolphin densities, I took the average density over repli- cates from column 3, Table 2. This procedure re- sults in a density estimate of 0.40 dolphin km- (1.36 dolphins/n.mi.^), a value very close to the estimate obtained using the method described above (0.41 dolphin km-, 1.41 dolphins/n.mi.^), but having a variance twice as large (0.1837 vs. 0.0941. Because of the higher variance, it can be argued that the first method used, because it takes into account both average herd size and average herd density, is preferable in this case. The numbers of dolphins entering or leaving the river at Sebastian (4 groups totaling 15 animals) and Fort Pierce Inlets (none sighted) were negligi- ble and were judged as insignificant to the total population size. Two of those groups were entering the river against an outgoing tide, one moved from the river into the inlet on an ebbing tide, then turned around and reentered the river, and one was milling within the inlet (Table 3). The surprisingly low estimate does, of course, raise an important question. Is the population of bottlenosed dolphins in the river complex always this small (and only appears larger because of periodic concentrations of animals in limited areas) or is it augmented seasonally by influxes of animals from other areas migrating into,the rivers in response to the movement of fishes? Caldwell ( 1955) and others have suggested lim- ited home ranges for bottlenosed dolphins. Wells et al.," Irvine et al.,'- and Shane and Schmidley "Wells. R. S.. A, B. Irvine, and M. D. Scott 1977, Home range characteristics and group composition of the Atlantic bottlenosed dolphin Tur>ii(>ps tnirtcatus on the west coast of Flonda. In Proceedings lAbstr.l of the Second Conference on the Biology of Marine Mammals, San Diego, Calif., 12-15 Dec. 1977, p. l.i '■^Irvine, A. B., M D, Scott, and R. S Wells, 1977, Move- ments and activities of Atlantic bottlenosed dolphins. In Pro- ceedings lAbstr.l of the Second Conference on the Biology of Marine Mammals, San Diego. Calif, 12-15 Dec. 1977. p. 16. (see footnote 10) have all clearly demonstiated limited home ranges for portions of the popula- tions in their study areas; Wells et al. (see footnote 1 1 ) have shown differences in size and locations of home ranges based on age and sex classes, and all these authors have reported some movements ol' animals into and out of their study areas. Caldwell and Caldwell (1972) summarize the views of the fishermen from eastern Florida that there are "river" and "ocean" T. Iriniciiliis popula- tions. Caldwell et al. (1975) presented evidence from the distribution of cases of "Lobos" disease (lobomycosis) in bottlenosed dolphins that indi- cate greatest susceptibility to the disease in riverine-estuarine stocks and suggest isolation of river from ocean stocks. Shane''' reported that the offshore population of bottlenosed dolphins off Texas rarely interacted with the bay population but that the winter popu- lation in the Port Aransas area was at least twice as large as that in summer, because the bay popu- lation was augmented by "large numbers" of dol- phins entering that area for the winter either from the adjacent gulf or from adjacent bay systems. Whether or not a similar influx occurs in the In- dian River is unclear. Additional surveys during the peak seasons of the most important midwinter fisheries (king and Spanish mackerel, bluefish, spots, and pompano) might provide answers. In considering the questions of the dolphins' population size and alleged damage to nets, it should be remembered that bottlenosed dolphins, at least in some areas, are not uniformly distrib- uted but tend to concentrate in areas of high fish productivity (Leatherwood and Platter see foot- note 9) which are often areas of highest human use (Leatherwood 1975). Irvine et al. (see footnote 12), for example, reported that short-term movements of bottlenosed dolphins near Tampa Bay appear to correlate with movements of mullet. Frequent joint use of resources by dolphins and humans make the dolphins highly visible and could result in inflated estimates of their numbers. Even if not augmented seasonally by immigra- tion from other areas, the relatively small dolphin population in Indian and Banana Rivers could be responsible for net damage of the types reported by Cato and Prochaska ( 1976). Feeding by dolphins near seine and gill net fisheries is well known '^Shane. S, H. 1977, Population biology of Twr-'iio/w /ra(i- latus in Texas. In Proceedings (Ab.str.l of the Second Confer- ence on the Biologvof Marine Mammals. San Diego. Calif. 12-15 Dec. 1977. p. .57. ' 57 FISHERY BULLETIN VOL 77, NO 1 ( Leatherwood 1975), and dolphins sometimes be- come entangled as a consequence (Mitchell 1975). An entangled adult dolphin, struggling for escape, is certainly capable of ripping a small-mesh net apart. Further, bottlenosed dolphins have been documented stealing fish from longlines (Iver- son'''). Even so, dolphins may not actually be re- sponsible for all or even the majority of the dam- age in Indian River. Cato and Prochaska (1976) refer to damage to nets by sharks and cite the need for deterrents. D. K. Caldwell'^ reviewed the evi- dence and concluded that the majority of damage to nets in the Indian River was probably caused by sharks and not by dolphins, citing as support numerous reports by fishermen and others work- ing the area of sharks around nets. He also con- cluded, however, that dolphins were stealing fish and damaging gear in the king mackerel fishery in the nearby Atlantic Ocean. During the aerial sur- veys, I observed huge concentrations of sharks on the sand bars at the entrance of St. Lucie Channel. Therefore, the question of what causes the damage to nets is still open and regulation of the dolphin population based on its supposed size and levels of damage to the fisheries would be premature. Irvine et al. (see footnote 12) reported that in spring calves composed as much as 147^ of the bottlenosed dolphin population near Tampa Bay. Shane (see footnote 13) reported that calves con- stituted from 3.65% (February) to 12.92% (May) of the dolphins in the Port Aransas area (x = 7.61); Leatherwood et al. (1978) reported summer figures from 7.7 to 7.9% calves for coastal Ala- bama, Mississippi, and Louisiana. The 8.1-10.1% calves observed during this survey therefore are well within the reported ranges of percentages of calves in local bottlenosed dolphin populations. It has been noted that in areas where tidal flow is negligible, as is the case within these rivers, dolphin movements appear to be related to some factor other than tide (Shane and Schmidley see footnote 10). Shane and Schmidley found that the dolphins in areas of swiftest current moved against tidal flow. The inability to ascertain a relationship between swimming direction of '■•Iverson.R, T. B. 1975. Bottlenosed dolpliins stealing fish from Hawaiian fishermen's lines. Unpubl- manuscr., 12 p. Southwest Fisheries Center Honolulu Laboratory, National Marine Fisheries Service. NOAA, P O. Box .3830, Honolulu, HI 96812. "'D. K. Caldwell. University of Florida, Biocommunication and Marine Mammal Research Facility. Rt. 1, Box 121, St. Au- gustine, FL 32084, pers. commun. September 1977. groups and tidal flow in the river inlets in this study is perhaps related to our small sample size. Manatees Hartman (see footnote 5) and Irvine and Campbell (1978) reported that Florida manatees concentrated near warmwater refugia during winter months but dispersed during the remain- der of the year. The 151 manatees (some no doubt repeats on successive days) sighted during this survey were distributed throughout the nearshore waters of the Indian-Banana River complex, in- cluding several less saline canals, and animals were not concentrated near the St. Lucie power station or other potential warmwater areas where winter concentrations have been reported (Irvine and Campbell 1978). No manatees were observed in the deeper open water of the rivers. All were in shallower coastal waters, marinas, creek mouths, bayous, and canals. The number of calves ob- | served, composing from 9.9 to 13.2% , depending on the correct classification of the intermediate-sized animals observed, falls within the ranges of 9.6% calves (winter) and 13.4% calves (summer) re- ported by Irvine and Campbell (1978). ACKNOWLEDGMENTS I thank the following for help with this project: aircraft from Orlando Flying Service, Orlando, Fla., were flown by Steve Negrich. Glen Young, Sea World of Florida, flew as second observer. Both men were very competent and patient with the arduous flight schedule. Ed Asper,Sea World, Inc., provided observers at the ocean inlets and offered valuable advice on the animals of the river. Leola Hietala and Louise Anello Irwin typed the manu- script. D. K. Caldwell, A. B. Irvine, Mari Schaef- fer, J. Powers, T. J. Quinn, S. Shane, and R. Wells reviewed the manuscript and made useful sugges- tions for its improvement. Fishery Bulletin re- viewers L. L. Eberhardt and J. R. Gilbert were especially thorough in their treatment. LITERATURE CITED Caldwell. D, K 1955. Evidence of home range of an Atlantic bottlenose dolphin J. Mammal. 36:304-305. C.-^LDWELL. D. K., AND M. C. CALDWELL, 1972. The world of the bottlenosed dolphin J B Lippin- cott Co., Phila.. 157 p. 58 LEATHERWOOD AERIAL SURVEY OF DOLPHINS AND MANATEES Caldwell. D. K.. M. C. Caldwell. J. C. Woodard, L. ajello, W. KAPLAN, and H. M. MCCLURE 1975. Lobomycosis as a disease of the Atlantic bottlenosed dolphin ^Tiirsiops truncatus Montagu. 1821), Am J. Trop. Med. Hygiene 24:105-114. CATO. J. C, AND F. J. PROCHASKA 1976. Porpoise attacking hool < f a 79 KiSHKKV BULLETIN' VOL FlGl'RE 11 ^Sqiiilla emptisa. A-B: stages VI and VII respectively, ventral views. Fifth maxilliped (Figure 13Ri with propodus bearing 18 to 40 spinules, carpus with 9 to 20 .spinules. Pereiopods (Figure 14P to 14Ri slender with or without distal segment of e.xopods setose. Pleopods (Figures 22A to 22C; 23A. 23Bi with distal lobe of gill pinnate. Uropod (Figure 26C) with basal segment ol' exopod armed with 6 to 8 spines, apical segment of exopod with 17 to 60 plumose setae. Endopod of uropod with 10 to 38 plumose setae. Inner spine of basal prolongation with blunt spine on outer prox- imal margin. Basal uropod segment with a dorsal spine on distal margin. Telson (Figure 141) with 8 to 10 pairs of inter- mediate denticles, 26 to 34 submedian denticles. P()stlar\a (Iigure 2 Measurements (mmi: RL, 0.50 to 0.60: CL, 2.90 to 3.30; TW, 2.55 to 3.10; RVV. 0.65 to 0.75; tL. 1.95 to 2.55: TL, 12.3 to 14.20. Eyes large, extending to middle of second seg- ment of antennular peduncle. Cornea bilobed, set obliquely on stalk. Ocular scales rounded, anterior margin of opthalmic somite evenly rounded. Antennular process produced into blunt spine directed anterolaterally, antennular peduncle slightly shorter than carapace, antennule ( Figure 25Ai with inner flagellum bearing 34 segments, median flagellum with 30 segments, outer flagel- lum with 15 segments and 22 aesthetascs ar- ranged in eight groups of 2 or 3. Antenna (Figure 25Bi with 63 to 75 plumose setae, endopod with 16 segments. Rostral plate wider than long, lateral margins tapering to rounded apex. Median carina present. Anterolateral angle of carapace without spine, almost forming right angle, posterolateral mar- gins broadly rounded, carinae poorly developed, median carina not bifurcate anteriorly or pos- teriorly, intermediate and lateral carinae present, reflected carinae absent. Mandible (Figure 25C) serrate, mandibular palp absent. Maxillule (Figure 25D) with coxal endite bear- ing 26 to 27 strong marginal teeth and 6 to 9 small medial teeth. Basal endite with one spine flanked 80 MORGAN and PROVENZANO, DEVELOPMENT OF SQUILLA EMPUSA LARVAE AND POSTLARVA FIGURE 18. Squilla empusa. A-E: stage VII, first to fifth pleopods re- spectively. by one strong seta. Distal margin of basis with three setae. Endopod present as palp on distal margin of basis, armed with two setae. Maxilla (Figure 25E) four-segmented, two prox- imal segments with endites, second bilobed. Five pairs of maxillipeds (Figure 25F to 25J) each maxilliped with one epipod. First maxilliped (Figure 25F) with distal margin of propodus bear- ing 14 teeth, inner margin with 48 to 50 strong setae arranged in 10 transverse rows, 2 or .3 most distal setae spatulate with strong setules. Second maxilliped (Figure 25Gi with dactylus bearing six teeth, pectinate propodus with three moveable proximal spines, dorsal ridge of carpus undivided. Pereiopods (Figure 26A) with setose endopod and exopod. Last three thoracic somites with unarmed sub- median and intermediate carinae. Lateral process of fifth thoracic somite subacute, sloping pos- teriorly. Lateral processes of next two somites bilobed each with a small anterior lobe and a large broadly rounded posterior lobe. Median ventral keel of eighth somite with rounded apex. Abdomen broad, depressed, Submedian, inter- mediate, lateral, and marginal carinae present. Abdominal spines in submedian carinae of sixth somite, intermediate and lateral carinae of fifth and sixth somites, and marginal carinae of fifth somite, formula: submedian 6; intermediate 5 to 6; lateral, 5 to 6; marginal, 5. Sixth abdominal so- mite with sharp ventral spine anterior to uropod articulation. Pleopods (Figure 26B to 26Fl with gills. Pleopod setation presented in Table 2. Uropod (Figure 26G) with eight graded move- able spines on outer margin of proximal segment of exopod, last extending to middle of apical seg- ment. Apical segment of exopod extending pos- teriorly to apex of intermediate spine. Basal seg- 81 FISHERY BULLETIN: VOL 77. NO 1 Table 2. — Number of setae on margins of pleopods of the post- larva ofSqutlla empusa. Figure 19- — SquiUa empusa. stage VIII. ventral view. merit of uropod with dorsal spine on distal margin. Basal prolongation of uropod with two spines, me- sial longer. Single rounded lobe between spines of prolongation. Mesial margin of basal prolongation sinuate. Telson (Figure 24) as wide as long, median carina with sharp posterior spine, prelateral lobes absent, postanal ventral carina absent, subme- dian teeth with moveable apices, denticle formula: submedian, 8 to 10; intermediate, 7 to 10; lateral, 1. Postlarva white with brown chromatophores on eyes and all appendages except mouthparts. Carapace with few chromatophores. Exposed thoracomeres with chromatophores along pos- terior margin. Pleomeres with chromatophores along intermediate and lateral carinae and pos- terior margin. Telson with chromatophores along curved dorsal striations and posterior spine. Abdominal somite structure 1 2 3 4 5 Protopod Endopod Exopod 12-15 55-60 55-59 12-15 60-71 61-64 12-15 66-72 62-64 12-14 63-72 61-63 8-11 59-67 53-56 DISCUSSION Brooks 11878) and Faxon ( 1882) have produced the only prior publications on the larvae ofSquilla empusa. Brooks partially described the develop- ment by reconstruction, and Faxon held an un- identified last stage through metamorphosis to at- tempt to identify it with the adult. .'Although Brooks* illustrations and descriptions indicate that he probably was working with S. empu.'^a, Faxon's do not. The carapace of Faxon's last stage larvae appears to be too broad, the posterolateral spines are too short, and a spinule is present on the posterior margin of the carapace midway between the dorsal and posterolateral spines. Further- more, in Faxon's illustrations both the last larval stage and postlarva have broad abdomens with the first pleomere being as wide as the sixth, but in .S. empusa, the abdomen is tapered with smaller an- terior pleomeres grading into larger posterior ones. Faxon collected his larva from Newport, R.I., where only four species of stomatopods are known to reside: S. empusa. Nannnsquilla grayi. Hetern- squilla arinata. and Platysquilla cnodis (Manning 1974). Because the telson of Faxon's postlarva bears four intermediate denticles, it can be attrib- uted to the Squillidae, and S. empusa is the only squillid known to inhabit the area; the other three species belong to the Lysiosquillidae. Few larval descriptions have been made on southern species of squillid larvae, and of these none possesses the pair of spines on the posterior margin of the carapace, seen in Faxon's larva, nor does S. em- pusa. If Alikunhi (1952, 1967) was con-ect in his identification of the late larva and postlarva, these spines occur on Cloridopsis scorpio from the In- dian Ocean. The spines may be only a specific character or they may be diagnostic for the genus Cloriflopsis. The only member of that genus in- habiting the waters of the Western Atlantic is C (luhia which ranges from South Carolina to Brazil. Perhaps Faxon collected a larva of C. duhia which drifted north with the Gulf Stream. Until more larval descriptions are worked out for western At- 82 MORGAN and PROVENZANO DEVELOPMENT OF SQUILLA EMPUSA LARVAE AND POSTLARVA FR;URE 20.— Squilla cmpusa. A-E: stage VTII, first to fifth pleopods re- spectively. lantic species of stomatopods, the identity of Fax- on's larva will remain uncertain. To identify larvae of S. empusa the spinules of the carapace and denticles of the telson should be examined. Stages I and II possess four spinules on the lateral margin of the carapace and four inter- mediate denticles. The third to ninth stages are armed with six spinules on the lateral margin of the carapace. There are two anterior and three posterior spinules all ventrally directed, and one median spinule laterally directed. The telsons of stages III to IX have S to 10 mtermediate denti- cles. Except for Provenzano and Manning (1978), who reared Gonadactyius oerstedii from hatching to metamorphosis, experimenters who have at- 83 FISHERY BULLETIN VOL 77. NO 1 Figure 21. — SquiUa empusa. stage IX, ventral view. tempted to hatch and rear larvae either to link them with an adult or to describe the entire larval development have been unsuccessful at rearing larvae past the first pelagic stage because the lar- vae could not be induced to feed (Manning and Provenzano 1963). Pyne ( 1972) was unable to rear Pterygosquilla arinata schizodontia eggs past the first pelagic stage, but did hold stages I to VII larvae taken from the plankton for periods as long as 10 to 16 days wherein the larvae passed through at least one ecdysis. Pyne also found it possible to keep later stage larvae for very much longer periods of up to 165 days during which time they molted as many as six times. Pyne reared his lar- vae in mass culture using 4-in (10.2-cm) finger bowls. Alikunhi ( 1975) reared planktonic larvae of Oratosquilla nepa in aquaria through metamor- phosis until they reached adulthood, bred, and produced eggs. The manner in which all .species of Squillidae develop is similar. All Squillidae hatch as pseudozeae with four pairs of pleopods and develop into the alima form. Some, if not all, pass through two propelagic stages before the first truly planktonic stage. The alima is characterized by a telson with four or more intermediate denticles, the distance between the submedian spines in later stages being not larger than that between the intermediate and submedian spines, the pro- podus of the second maxilliped bearing three basal spines, the antennular somite generally having a median spine, the posterolateral spine of the carapace having a basal accessory spine, the eye- stalks long, and the exopod of the uropod being longer than the endopod (Gurney 1942, 1946). Alikunhi (1952) added that alima larvae possess carapaces armed with a varying number of spinules on the lateral margins, the sixth abdomi- nal somite usually being equipped with a pair of submedian dorsal spines, and in advanced larvae, the posterolateral angles of the abdominal somites ending in acute or subacute spines. Alikunhi (1952) noted that between allied species, the specific differences are often "trivial" but remarkably constant. He determined that some features, such as the size of the final pelagic stage, the shape and spinulation of the carapace, telson, and uropods.and the presence or absence of teeth other than the terminal on the dactylus of the second maxilliped, hardly show any variation within a species. These characters may be used for specific determinations but are presently of little aid in defining generic alliances for three reasons. First, relatively few stomatopods have been as- sociated definitely with the adult of the species. Second, most of these have had described only one larval .stage of the entire development. Only 19 of the Squillidae have been definitely connected with their larval forms. Provenzano and Manning (1978) listed 17 species of identified stomatopod larvae, but O. masnavensis was omitted and S. empusa has now been added to the list. Of the 19 species, only 2. P. arinata schizodentia andS. em- pusa, have been reared in the laboratory through essentially their entire pelagic development. Two additional species have been hatched from eggs obtained from a known adult and the first pelagic stage described, i.e., Chirida vhoprat by Gurney 84 MORGAN and PROVENZANO DEVELOPMENT OF SQUILLA EMPUSA LARVAE AND POSTLARVA •"'11 III r^hMk *!i% FIGURE 22— Squilh empusa. A-C: stage IX, first to third pleopods respectively. Figure 2Z.—SquiUa empusa. A-B: stage IX, fourth to fifth pleopods respectively; C: stage IX, uropod. 85 FISHERY BULLETIN VOL 77. NO 1 FlOURE 24. — Squilla empiisa. postlarva. dorsal view. ( 1946) andS. mu/ilis by Giesbrecht ( 1910), and the remainder have had the last stage described by holding the final pelagic stage until metamor- phosis occurred and the stomatopod could be corre- lated with an adult of the species. Reconstructions of the larval development of three species, .S. man- tis by Giesbrecht ( 1910), O. oratoriu by Komai and Tung (1929), and O. maasavensis by Gohar and Al-Kholy (1957), were attempted by collecting larval stages from the plankton and piecing them together. Metamorphosis from the last larval stage was obtained for O. massavensis, but since the larvae were not reared, the larval histories may not be entirely factual. Thus, because so few larval forms have been identified and because most of these have had only one stage described, it is difficult to discover which characters are shared by all members of a genus and which characters are only specific. Of the nine genera of Squillidae which have had larvae described, four genera have had one or more larval stages of a single species described, four more genera have had two species identified, and one genus has had larvae of eight species described. A determination of generic characters is difficult at best for those genera for which only one or two species have been described, especially since there are no adequately rep- resented genera with which to compare charac- ters. The third reason why specific characters are of little help in generic definition lies in the incom- plete descriptions of the larval stages. Characters noted by one author are frequently omitted by another, so that even for the genus Oratosquilta, represented by larval descriptions of eight species, consistent characters are difficult to recognize. An assessment of larval characters was at- tempted to determine which ones were constant within each genus. Most characters mentioned in the descriptions appeared to vary a gr-eat deal for the species within a genus, or the characters that varied relatively little within a genus were fre- quently found in other species of different genera. Of possible value in defining generic associations is the presence or absence of teeth (other than the terminal ) on the dactylus of the second maxilliped. These teeth occur during the last stage in the genera Anchisquil la , Clorida , Pterygosquilla , and Squilloides, although for each of these genera lar- vae of only one species have been described. The dactylus of P. annata schizodontia is armed with 5 to 8 teeth and the first stage is easily diagnosed by the posterior spines of the carapace which bear 6 to 16 spirally arranged, proximal spinules. The spinules are replaced by three ventral spinules in the remaining stages (Pyne 1972). The dactyl of the second maxilliped is equipped with two free teeth in A. fasciata, three teeth inS. lata, and inC. latreillei is usually armed with one tooth, rarely with two (Alikunhi 1952). Newly hatched larvae of C. choprai were too inadequately described to be compared withC. latreillei (Tweedie 1935; Gurney 19461, but the dactylus of the second maxilliped was observed to be unarmed. This is not surprising since C. latreillei and S. lata develop teeth on the dactylus of the second maxilliped in the later stages and P. armata schizodontia develops its first tooth in the third stage. 86 MORGAN and PROVENZANO DEVELOPMENT OF St^CILLA E.VtPL'SA LARVAE AND POSTLARVA 1 A.R F J 1 1 0mm 1 C-E 1 Figure 25. — Squilla empusa. postlarva. A, antennule; B. antenna; C, mandible; D. maxillule; E, maxilla; F-J, first to fifth maxillipeds respectively. 87 FISHERY BULLETIN VOL 77. NO 1 I, ,^.^f?ffe mm 0mh ilM^. Figure 26. — Sqmlla cmpusa, postlarva. A, first pereipod; B-F. first to fifth pleopods respec- tively; G, uropod. 88 MORGAN and PROVENZANO: DEVELOPMENT OF SQL' ILL A KMPl'SA LARVAE AND POSTLARVA The second maxilliped of the remaining de- scribed larvae is unarmed throughout the larval development. To distinguish these genera, other characters, such as the presence or absence of a spine on the basis of the second maxilliped, must be relied on. The spine is definitely born by seven of the eight species oi OratosquiUa, but was not mentioned for O. massavensis. Other species, Squilla enipusa. P. armata schizodontia , Aliina hyalina, and Meiosquilla lebouri have the spine, while Harpiosqiiilla harpax and A. fasclata definitely do not. The development of epipods on five pairs of maxillipeds in older larvae appears to be a generic character of Squilla as most other genera bear four pairs of epipods. Characters such as rostral length and spinula- tion. carapace and telson shape, size, and spinula- tion, and overall body size and appearance have been too variable within the limited number of species presently described to use them in defining generic associations of the larvae. Deriving characters which apply to the youngest larvae as well as the old will be difficult since far fewer characters are present in the early stage larvae, and the gross appearance of the young larvae is very similar due to the small degree of differentia- tion. Other characters such as antennular seg- mentation, mouthpart morphology, setation, spi- nation of the maxillipeds, or the presence of ocular, antennular, epistomal, or basal uropodal spines may also need to be examined. The setation and spination of the first maxilliped may be of great value in defining alliances of the species as well as in making specific determinations. How- ever, many more complete descriptions of the lar- val developments undergone by the various species must be accomplished before larval characters can be used in establishing generic re- lationships. The postlarva of Squilla empusa exh-ibited the basic features of first stage postlarva as deter- mined for other species by Alikunhi (1967). These include the absence of anterolateral spines on the carapace, the extremely poorly developed carina- tion of the carapace, acutely pointed marginal denticles of the telson, and moveable apices of the submedian spines of the telson. As with the adult, the postlarva possesses the full complement of teeth on the raptorial dactylus, just as Alikunhi 11967) found. Furthermore, the five pairs of epipods found in the adult are also possessed by the postlarva. Other adult characters were de- veloped upon the next molt. The dorsal carinations of the carapace were developed, the lateral proces- ses of the exposed thoracic somites five through eight resembled those of the adult, the marginal denticles of the telson were not as acute, and the submedian spines were fixed. The abdominal spi- nal formula was still not equal to that of the adult. Nevertheless, after the postlarva had undergone its first molt more than enough characters were shared with the adult to make a definite determi- nation of the species. CONCLUSIONS 1. Squilla einpusa undergoes nine pelagic stages before attaining the postlarval stage. 2. The last stage stomatopod larva and post- larva described by Faxon (1882) are not S. t'inpusd. 3. Larvae of .S. cmputia may be identified by the spinules of the carapace and the inter- mediate denticles of the telson. Stages I and II possess four spinules on the lateral margin of the carapace and four intermediate denti- cles. The third to ninth stages are armed with six spinules on the lateral margin of the carapace. There are two anterior and three posterior spinules all ventralh' directed, and one median spinule laterally directed. The telsons of stages III to I.X have 8 to 10 inter- mediate denticles. 4. Rostral length and spinulation. carapace and telson size and spinulation, and overall body size and appearance probably are specific rather than generic characters. 5. The presence or absence of teeth on the dac- tylus of the second maxilliped. the presence or absence of a spine on the basis of the sec- ond maxilliped. and the number of epipods may all be useful characters in determining generic status of larvae belonging to the Squillidae. However, many more complete descriptions of the larval developments un- dergone by the various species are needed before larval characters can be used in estab- lishing generic relationships. ACKNOWLEDGMENTS We are indebted to the National Science Found- ation for its support of this work under grant DEB76-11716 to the Old Dommion University Re- search Foundation. 89 FISHERY BULLETIN VOL 77. NO. 1 LITERATURE CITED Alikl'nhi. k. h. 1952. An account of the stomatopod larvae of the Madras plankton. Rec. Indian Mus. (Calcutta! 49:239-319. 1967. An account of the post-larval development, moult- ing, and growth of the common stomatopods of the Madras coast. In Symposium on Crustacea. Ernakulam, India, 1965, p 824-939. Mar. Biol. Assoc. India, Symp. Ser. 2. 1975. Studies on Indonesian stomatopods 1. Growth, maturity and spawning of Squilla nepa. Bull. Shrimp Cult. Res. Cent. 1(11:27-32. BROOKS. W. K. 1878. The larval stages of Squilla empusa Say. Johns Hopkins Univ., Chesapeake Zool. Lab. Sci. Res. 1878:143-170. Burrows. M. 1969. The mechanics and neural control of the prey cap- ture strike in the mantid shrimps S(//;i //a andHemisquil- la. Z. vgl, Physiol. 62:361-381. DRAGOVICH. A. 1970. The food of skipjack and yellowfin tunas m the At- lantic Ocean. U.S. Fish Wildl. Serv., Fish. Bull. 68:445- 460. F.WON. W. 1882. I. — Crustacea. In A. Agassiz, W. Faxon, and E. L. Mark (compilersl. Selections from embryological mono- graphs. Mem, Mus. Comp. Zool, (Harv. Univ. I 9(li, 14 plates. Fish. C. J. 1925. Seasonal distribution of the plankton of the Woods Hole region. Bull. [U.S.I Bur, Fish. 41:91-179. GIESBRECHT, W. 1910. Stomatopoden. Erster Theil. Fauna Flora Golfes von Neapel, Monogr. 33, 239 p. GOH.'^R. H. A. F., .-XNl) A. A. AL-KHOLY 1957. The larval stages of three stomatopod Crustacea (from the Red Sea). Publ. Mar. Biol. Stn., Al-Ghardaqa (Red Seal 9:85-130. GURNEY. R. 1942. Larvae of decapod Crustacea. Ray Soc. (Lond.i Publ. 129, 306 p. 1946. Notes on stomatopod larvae. Proc. Zool. Soc. Lond. 116(11:133-175. HlLDEBR.-\ND, H. H. 1954. A study of the fauna of the brown shrimp tPcnacux aztecus Ives) grounds in the western Gulf of Mexico. Publ. Inst. Mar. Sci., Univ. Tex. 3:233-366. Vol. 3, Crustacea. Wiley In- Kaestner. a. 1970. Invertebrate zoology, terscience, N.Y., 523 p. KOMAi. T., AND Y. M. Tung. 1929. Notes on the larval stages of Squilla oratoria, with remarks on some other stomatopod larvae found in the Japanese Seas. Annot, Zool. Jpn. 12:187-214. LEBOUR, M. V. 1924 Young anglers in captivity and some of their enemies. A study in a plunger jar. J. Mar. Biol. Assoc. U.K. 13:721-734. MacGinitie, G. E.. and N. MacGinitie. 1968. Natural history of marine animals, 2d ed. McGraw-Hill, NY., 523 p. Manning, R, B, 1969. Stomatopod Crustacea of the western Atlan- tic, Stud. Trop. Oceanogr. (Miami) 8, 380 p. 1974. Marine flora and fauna of the northeastern United States. Crustacea: Stomatopoda. U.S. Dep. Commer., NOAA Tech. Rep. NMFS CIRC-387, 6 p. Manning. R. B., and A. J. Provenzano, Jr. 1963. Studies on development of stomatopod Crustacea I. Early larval stages of Gonodactylus oerstedii Han- sen. Bull. Mar. Sci. Gulf Caribb. 13:467-487. PICCINETTI, C, AND G. P. MANFRIN 1970. Prime osservazioni suH'ahmentazione di Squilla mantis L. Bologna Univ. Inst. Zool. Note 3l 101:251-263. PROVENZANO, A. J., JR . AND R. B. MANNING 1978. Studies on development of stomatopod Crustacea II. The later larval stages oi Gonodactylus oerstedii Hansen reared in the laboratory. Bull. Mar. Sci. 28:297-315. PYNE, R, R. 1972, Larval development and behaviour of the mantis shrimp Squilla armnta Milne Edwards (Crustacea: Stomatopodal. J. R. Soc. N.Z. 2:121-146. Randall, J, E. 1967. Food habitsof reef fishes of the West Indies. Stud. Trop. Oceanogr. (Miami) 5:665-847, RKINT.JES. J. W., AND J, E. KING. 1953. Food of yellowfin tuna in the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 54:91-110. SUNIER. A. 1917. The Stomatopoda of the collection "Visscherijsta- tion" at Batavia. Contrib. Faune Indes Neerl. 1(4):62- 75. TWEEDIE. M. W. F. 1935. Two new species of Squilla from Malayan waters. Bull. Raffles Mus. 10:45-52. 90 VARIATION IN THE FOURBEARD ROCKLING, ENCHELYOPUS CIMBRIUS, A NORTH ATLANTIC GADID FISH, WITH COMMENTS ON THE GENERA OF ROCKLINGS Daniel M. Cohen' and Joseph L. Russo^ ABSTRACT Enchelyopus cimbriun, the fourbeard rockling, is a gadid fish living around the rim of the North Atlantic Ocean. It varies geographically in color pattern; anal, dorsal, and pectoral fin ray counts; and vertebral and gill racker counts. There is a lack of overall concordance in patternsof vanation in color and meristics. Morphometric characters do not distinguish populations from different geographical areas, and the fourbeard rockling is considered to be a single species. New distributional records include the Gulf of Mexico, West Greenland, and West Africa. We classify the rockiings as a tribe, Gaidropsanni, of the subfamily Lotinae. Characters previously used to separate rockiings into five genera — skull shape, vomerine tooth patch shape, number and distribution of supratemporal pores, length of first dorsal fin ray, and size of jaw teeth — do not distinguish nominal genera. Number of snout barbels divides rockiings into three groups that we tentatively recognize as genera: Gaidropsarus. the threebeard rockiings, with two snout barbels; Enchelyopus, the fourbeard rockling. with three snout barbels; and Ciliata, the fivebeard rockiings. with four or more snout barbels. Onogadus and Antonogadus are referred to the synonymy of Gaidrop- sarus. The correct generic name for the fourbeard rockling isEnckelyopus Bloch and Schneider 1801 , with Rhinonemus Gill 1863 as a junior synonym. It is not preempted by Enchelyopus Gronovius 1760 in Zoarcidae. which was used in a work that was not consistently binominal. The fourbeard rockling, Enchelyopus cimbritis, is a locally abundant gadid fish found around the margins of the North Atlantic Ocean. Although this fish has been recorded in the literature for more than 200 yr, many aspects of its biology are obscure. Adults are sedentary bottom dwellers taken at depths ranging from about 1 to 650 m [we have been unable to verify depth records to 1,325 m given by Goode and Bean ( 1896) ]. There is some indication that seasonal offshore-onshore move- ments occur (Bigelow and Schroeder 1953; Tyler 1971). The pelagic larval stages are similar in appearance to young hakes ( Urophycis ) and some- times occur in silvery swarms near the surface (Bigelow and Schroeder 1953). Recent collections discussed in this paper show that fourbeard rockiings are more widely distrib- uted than previously was known and that geo- graphical variation is present. One of our objec- tives in this paper is to describe, compare, and 'Systematics Laboratory. National Marine Fisheries Service, National Museum of Natural History, Washington, DC 20560. ^Systematics Laboratory, National Marine Fisheries Service, National Museum of Natural History, Washington, DC; pres- ent address: Department of Biological Sciences, The George Washington University, Washington, DC 20006. Manuscript accepted August 1978 FISHERY BULLETIN VOL 77. NO 1, IHTH evaluate geographical variation of selected characters and to show that a single species is represented throughout the range of the fish. The rockling group of the family Gadidae, which is characterized by several distinctive features, recently was divided into five genera (Wheeler 1969), although most ichthyologists have recog- nized only three (albeit under a variety of names). The second of our objectives is to show that at present there are valid reasons for only three. The fourbeard rockling is currently named En- chelyopus cimbrius by North American ichthyologists and Rinonemus cimbrius by Euro- peans. Our final objective is to show that En- chelyopus is the correct generic name. METHODS All observations were made on museum speci- mens listed in the Appendix. Counts of dorsal and anal fin rays and vertebrae were taken from X-ray photographs. Vertebral counts do not include the terminal ural element. Gill raker counts include all rakers on upper and lower arms of the first arch. Head pores were examined with the aid of a compressed air jet. Measurements and their 91 FISHERY BULLETIN VOL 77. NO 1 statistical analysis are described under Body Proportions. Statistical tests were performed on the IBM :i70-148' computer at The George Washington University, using computer pro- grams written and maintained at the Systematics Laboratory, NMFS, NOAA. and following .statis- tical methods presented by Zar (1974). GEOGRAPHICAL VARIATION The distribution of the fourbeard rockling may be summarized as the coastal waters of the North Atlantic. In the western Atlantic the species oc- curs in: West Greenland (new record); the north- western Gulf of Saint Lawrence and around New- foundland as well (Leim and Scott 1966 and this paper) to Cape Fear (about lat. 34°N) ( Bigelow and Schroeder 1953); the northeast coast of Florida (Bullis and Thompson 1965); off the Florida Keys (new record); and in the northern Gulf of Mexico (new record). In the eastern Atlantic the species occurs: around Iceland (Saemundsson 1949) and the Faroes (Joensen and Taaning 1970); from northern Norway at about lat. 71°N in the Barents Sea and south along the coasts of Scandinavia (Andriyashev 1954); in the western Baltic (rarely to the Gulf of Finland, Svetovidov 1973); th rough - ^Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. out the Noi'th Sea and around the British Isles to the northern Bay of Biscay (Wheeler 1969; Du Buit 1968); and off Cape Blanc, Mauritania (new record). It is not known from the Mediterranean. Figure 1 shows the approximate localities from which we have studied specimens. More detailed locality data are presented in the Appendix. Sampling Areas We have compared fish from the following geo- graphical areas. Gulf of Mexico. Only 3 localities are represented in our collections. These specimens are among the most darkly pigmented of any we have studied. Southern Atlantic. Specimens taken from the South Carolina coast at about lat. 33°N to about lat. 29^N on the east coast of Florida, which is as far south as specimens have been caught in the western Atlantic outside of the Gulf of Mexico. There is no reason to doubt that this population is continuous with those farther north, and the northern boundary as here given is arbitrarily limited by available study material. Intermediate. Fish caught in the vicinity of Cape Hatteras from about lat. 35°N to the vicinity of Norfolk Canyon at about lat. 37"N are included in Figure l. — Localities for our specimens of Efichelyopus cimbriu^. Some dots represent more than one collection. For detailed data on localities see Appendix. 92 COHEN and RUSSO: VARUTION IN FOURBEARD ROCKLING this area, which we separate because it is geo- graphically between the region to the south. where fishes are mostly dark colored. Northern Atlantic. This region extends along the western Atlantic coast from north of the vicin- ity of Norfolk Canyon to the northern North American limit of E. cimbrius occurrence. Greenland. A single specimen from West Green- land is apparently the only known occurrence of £. cimbrius from Greenland. Iceland. The region around Iceland. Europe. Although E. cimbrius occupies a con- siderable area we have examined only a small sample, mainly from Denmark and Norway. Africa. Two specimens from off the coast of Mauritania ca. lat. 21°N are the most southerly known. Color Enchvlyopus cimbrius from the Gulf of Mexico and Southern Atlantic areas have on the average more of the dorsal fin colored with dark pigment than do fourbeard rocklings from other areas (Ta- ble 1 ). We have attempted to quantify this charac- ter by coding it on a 0-10 scale with representing Table l. — Frequency distributions of degree of dorsal fin pig- mentation in Enchelyopus cimbrius from eight geographical areas. = no dark pigment in dorsal fin; 10 = entire fin darkly pigmented. Degree of pigmenta ion N Area 1 2 3 4 5 6 7 8 9 10 X SD Gull ol Mexico 2 1 5 2 4 1 1 2 18 62 2 1 Southefn Atlantic 1 - 2 6 1 6 17 6 6 2 47 67 19 Intermediate 7 6 4 6 2 1 3 1 30 3 6 2 8 Northern Atlantic 29 5 7 3 — 2 46 18 13 Greenland 1 1 5 - Iceland 5 2 2 1 ■* 10 19 11 Europe 1 26 1 1 1 2 32 14 09 Afnca 1 1 2 1 5 — a fin with no dark pigment and 10 representing a fin that is completely dark. Values were subjec- tively assigned by a single observer (Cohen). Fig- ure 2A shows a New England fish that would be coded as 1; Figure 2B shows the color pattern of a fish from the Gulf of Mexico, which would be coded as 6. Note that fish are morphologically inter- mediate and most variable in the Intermediate region'* where the mean is 3.8 and the standard deviation is highest at 2.8. Two other pigment characters were noted; how- ever, neither was quantified. Fish with light fins lacked dark pigment in the groove along the base of the row of filaments between the strong first dorsal ray and the beginning of the normally de- veloped dorsal fin ( Figure 3 A); fish with dark dor- sal fins had varying amounts of dark pigment in this region (Figure 3B). Also, in many Gulf, Southern Atlantic, and Intermediate fish the body was dusky; in most others the body was a rather light straw color. Meristics Frequencies of both anal fin rays and dorsal fin rays show a pattern similar to, though less pro- nounced than, that shown by dorsal fin pigmenta- tion in the western Atlantic (Tables 2, 3), with fish from the Intermediate area being intermediate between fish from the north and the south. Also, for anal fin rays the standard deviation is larger in fish from the Intermediate area than in adjacent samples. These two characters differ from dorsal pigmentation in having the highest mean in the Iceland sample. Frequencies of pectoral fin rays and vertebrae for North American samples from the Inter- mediate area have nearly identical means in both ■'Detailed descriptions of color variation in samples from Nor- folk Canyon and comparisons with specimens from the northeast coast of Florida have been presented by: P, Szarek. 1974 A preliminary study of Norfolk Canyon Enchelyopus cimbrius. Ichthyology Term Paper. Virginia Institute of Marine Science. Table 2. — Frequency distributionsof numbers of anal fin rays in Enchelyopus cimbrius from eight geographical areas. Number of anal fin rays N X Area 36 37 38 39 40 41 42 43 44 45 46 47 48 49 SO Gulf of Mexico 6 4 2 4 16 40 2 1 2 Southern Atlantic 6 1 1 18 8 3 46 40 8 1 1 Intermediate 1 2 5 4 7 2 2 2 — — 1 26 42 8 22 Northern Atlantic 8 8 9 13 9 2 2 1 52 43 5 1 7 Greenland 1 1 43 — Iceland 2 4 3 1 10 453 09 Europe 1 — 1 1 — 2 1 3 6 1 — — — 1 17 426 30 Afnca 1 1 2 44 5 — 93 FISHERY BULLETIN; VOL, 77. NO. 1 FIGURE2.—£nc/n>/yDpu.s(imfcriu.s. A, USNM 213501. standard length 282 mm, offCape Cod, dorsal fin pattern coded as 1 (see text). B, color pattern of a fish from the Gulf of Mexico (USNM 2 1 784.3 1 drawn on the outline of the fish shown in Figure 2 A, dorsal fin pattern coded as 6 (see text). Table 3. — Frequency distributions of numbers of dorsal fin rays in Emhelyapus ctmbnus from eight geographical areas. Number of dorsal fi n rays N X Area 45 46 47 48 49 50 51 52 53 54 55 SO Guit ol Mexico 1 1 11 3 16 47 07 Southern Atlantic 1 8 10 12 7 8 1 47 4/9 15 Intermediate 1 3 8 9 5 — 2 1 29 49 9 1 6 Northern Atlantic 1 — - 6 13 8 12 4 4 3 1 52 50 4 1 y Greenland 1 1 51 — Iceland 5 2 3 10 50 8 09 Europe 1 2 3 3 4 3 1 17 49 2 1 7 Africa 2 2 50,0 — of these characters with Northern Atlantic fish, rather than being intermediate (Tables 4, 5); how- ever, for pectoral fin rays, fish from these two areas have lower counts that are in between Gulf and Alantic, and Greenland, Iceland, and Europe samples. Iceland fish average highest of all in dor- sal and anal fin ray counts and in vertebral counts (not including the few specimens from Greenland and Africa). In pectoral counts, however, Iceland and Europe specimens have identical means. In total gill raker counts (Table 6) eastern At- lantic samples have higher means than do western Atlantic samples, with the highest standard de- viation being in the Northern Atlantic samples. Body Proportions Measurements were taken of the following eight body parts and compared for six of them in fish from the six geogi-aphical areas listed below and described previously under sampling areas (Greenland and Africa are not included in the present analysis). Linear regressions were calcu- lated for the following dependent variables, with standard length as the independent variable: 94 COHEN and RUSSO: VARIATION IN FOURBEARD ROCKLING Table 5. — Frequency distributions of numbers of pectoral fin rays in Enchelyopus cimbrius from eight geographical areas. FIGURE 3— Enchelyopus cimbrius. A. USNM 213501, head length 62.8 mm, off Cape Cod, note absence of dark pigment along base of fin with short rays. B, USNM 217843. head length 33.2 mm, Gulf of Mexico, note dark pigment along base of fin with short ravs. Table 4, — Frequency distributions of numbers of vertebrae in Enchelyopus ctmbnus from eight geographical areas. Number of v 'ertebrae N X Area 49 50 5t 52 53 54 55 SD Gulf of Mexico 9 7 16 51 4 05 Soutfiem Atlantic 1 1 18 22 10 52 51 8 09 Intermediate 4 7 12 6 1 30 52 8 1 Northern Atlantic 3 14 26 15 1 59 52 9 09 Greenland 1 1 54 — Iceland 4 3 3 10 53 9 09 Europe 2 3 7 3 15 52 7 1,0 Africa 1 1 2 545 — Number of pectoral fin rays Area 15 16 17 18 19 N X SD Gull of Mexico 1 2 9 6 1 19 17.2 0.9 Southern Atlantic 9 21 14 1 45 172 08 Intermediate 2 9 14 4 29 167 08 Northern Atlantic 5 21 21 5 1 53 165 09 Greenland 1 1 17 — Iceland 1 2 2 5 10 17 1 1 1 Europe 1 2 8 4 1 16 17 1 10 Afnca 2 2 16 — Table 6. — Frequency distributions of total numbers of gill rak- ers on first arch in Enchelyopus ctrnhrtus from eight geographi- cal areas. Number of g ill rakers Area 5 6 7 8 9 10 11 12 13 N X SD Gulf of Mexico 5 3 2 — 1 11 90 13 Southern Atlantic 2 9 12 17 4 44 9 3 1,0 Intermediate 1 1 11 6 5 24 9 5 1.0 Northern Atlantic 3 1 1 8 8 12 6 2 41 9 1 18 Greenland 1 1 9 — Iceland 2 5 2 1 10 10.209 Europe 6 4 3 1 1 15 10,1 1.3 Africa 1 — 1 2 10.0 — tic 53 (50.5-297); Iceland 10 (151-327); Europe 27 (93.8-300). Analysis of covariance was used to compare re- gression lines (Tables 7, 8) for six measurements that we have treated as linear based on a coefficient of determination ir^) of 0.73 or higher (Table 8). Two measurements, ventral fin length and barbel length, had coefficients of determina- tion ranging from 0.42 to 0.61 and were not further analyzed. Fishes from all si.x geographical areas demon- strated overall coincidence at the 0.05 level of sig- nificance in two characters, head length and upper jaw length. Hypotheses concerning overall coinci- dence of regressions for the other characters were rejected and hypotheses concerning the equality of slopes and intercepts were simultaneously tested. The hypothesis concerning the equality of slopes was rejected for the Dj-Dj distance versus stan- dard length regression lines. Regression data were snout to first dorsal fin (pre D, distance); first dor- sal fin to the dorsal fin beginning posterior to the row of small filamentous rays (D,-D:i distance); head length; pectoral fin length; upper jaw length; horizontal diameter of eye (orbit length); length of barbel on lower jaw; and ventral fin length. Num- bers of specimens measured and their size ranges (standard length in millimeters) were: Gulf of Mexico 17 (125-228); Southern Atlantic 46 (125- 263); Intermediate 29 1 104-202); Northern Atlan- TABLE 7. — Significance of differences in six morphometric characters in Enchelyopus cimhrius from six geographical re- gions. Independent variable is standard length. Overall Equality Equality Dependent variable N coincidence ol slopes of intercepts Pre Di distance 165 '0 0048 5342 "49 10 * D,-D3 distance 165 '00024 '00111 '0 0012 Head length 182 03004 — — Pectoral fin length 150 '00061 0617 '0 0011 Orbit lengh 166 '22 10 ' 0.1839 "2 4 10 ' Jaw length 166 2892 — — 'Rejection of hypothesis of equality at the 05 level of significance 'Reiection of hypothesis of equality at the 001 level of significance 95 FISHERY BULLETIN: VOL. Table 8. — Y intercepts in millimeters, slopes, coefficients of determination ir^). and N for regression lines calculated on Enchelyopus cimbnus from six geographi- cal areas. Independent variable is standard length. Measurement Geographical PreD, D,-Dj Head Pectoral Upper jaw Orbit area distance distance length fin length length length Gulf of f^lexico: V intercept 2 91 2 21 2 29 17 -3 08 10 Slope 16 12 18 14 11 04 r' 89 86 93 87 87 79 N 16 16 17 14 17 17 Soutfiern Atlantic: Y intercept Oil ■4 74 22 -0 89 -1 83 76 Slope 17 015 20 15 11 04 r' 96 89 94 091 89 090 N 43 44 46 43 44 44 intermediate Y intercept ■0,60 -0 74 ■0 71 48 ■2 69 -0 06 Slope 18 12 021 14 11 005 /■' 95 86 92 87 92 79 W 29 29 29 29 29 28 Northern Atlantic. Y intercept •0,32 47 ■0 43 -2 22 ■3 38 1 64 Slope 18 12 21 16 12 004 1-2 0,97 89 97 92 87 92 N 51 51 53 38 51 50 Iceland: Y intercept 0,47 3 59 2 09 6 02 ■5 71 2 65 Slope 0,17 10 20 12 13 03 r' 79 92 99 87 98 98 N 10 10 10 10 9 10 Europe: Y intercept -061 ■4 37 ■0 74 ■2 06 ■4,70 1,29 Slope 18 16 21 15 12 04 I-' 097 73 91 0,90 91 94 N 16 16 27 16 16 17 submitted to a Newman-Keuls multiple range test in order to determine which population sample or groups of population samples were different from others. This procedure failed to detect differences between any slopes, a not uncommon occurrence due to the fact that the analysis of covariance is a more powerful test than is the multiple range test. The sample from Iceland had the lowest slope at 0.10, the Northern Atlantic, Gulf of Mexico, and Intermediate samples each had a slope of 0.12, the Southern Atlantic sample had a slope of 0.15, and the sample from Europe had a slope of 0.16. The hypotheses concerning the equality of Y intercepts was rejected at the 0.0.5 level of sig- nificance for all four characters tested. These re- gression data also were submitted to a Newman- Keuls multiple range test in order to determine which population sample or groups of population samples were different from others. Again, this procedure failed to detect significant differences between any Y intercepts. If a more stringent 0.001 level of significance is used, only orbit length tests as being significantly different with respect to overall coincidence. Data for this regression from each of the six samples were submitted to a continuation of analysis of covariance to determine whether differences in the regression lines were attributable to the slopes and/or the Y intercepts. We accept equality of the slopes with a probability of 0.85. However we re- ject the equality of the Y intercepts after calculat- ing a probability of equality of 2.06 x 10"''. Re- gression data were submitted to a Newman-Keuls test, which failed to detect differences between any pairs of intercepts. Inspection of our data shows that rocklings from Iceland appear to have a proportionally larger eye than do other rocklings; however, our sample is small and may be biased by larger fishes; hence we do not draw inferences from this apparent difference. Although differences between samples appar- ently exist, we do not interpret them as represent- ing the kind of discontinuity that indicates dis- tinct species. Their significance is beyond the scope of this paper. Discussion We believe that the fourbeard cockling is best considered as a single species throughout its en- tire range. Differences in pigment pattern, meris- tics, and the relative size of several body parts do exist; however, there are neither trenchant dis- continuities in variation nor is there any overall 96 COHEN and RVSSO VARIATION IN FOL'RBEARD ROCKLING concordance in patterns of variation. Differences between and similarities among samples are summarized in Figure 4 and discussed below for meristics and color pattern. Differences in morph- ometric characters are so slight that we do not further consider them. Gulf of Mexico and Southern Atlantic samples are quite similar, although at this time the two might be semi-isolated from each other. The clockwise loop current system in the Gulf of Mexico provides a possible pathway for the disper- sal of young, pelagic stage rocklings out of the gulf; there is no present avenue for recruitment into the Gulf of Mexico. If the single rockling taken off the Florida Keys represents more than a stray, then perhaps Gulf of Mexico and Southern Atlantic populations are continuous; otherwise, the north Gulf-northeast Florida distribution pattern is similar to that noted first in fishes by Ginsburg (19521. Although E. cimhnus seems rare in the Gulf of Mexico its occurrence at two widely sepa- rated localities, with a collection of 16 individuals from one of them, indicates that the .species is estab- lished there. Although pelagic stages have not yet been taken from the Gulf of Mexico or Southern Atlantic areas, it seems reasonable to assume that they occur there and are available for dispersal in the Gulf Stream system. Rocklings from the Intermediate area are in- deed intermediate between adjacent populations to the north and south in degree of pigmentation and in dorsal and anal ray counts. Furthermore, for two of these characters, color and number of anal fin rays, the standard deviation is larger than in other populations, implying that recruits from different spawning populations are entering the area or that the characters are genetic and variabil- ity is being maintained during spawning in the Intermediate area. For two characters, numbers of vertebrae and pectoral fin rays. Intermediate and Northern Atlantic fish are nearly identical and differ from Southern Atlantic and Iceland sam- ples. These characters must be determined or mediated differently than are color pattern and dorsal and anal fin ray counts. Gill raker count appears to reflect still a third method of character determination as the means are different on the two sides of the Atlantic. Although pelagic early stages have not been taken in the Intermediate area, they may be available for dispersal to the northeast by means of the Gulf Stream and to the southwest in coastal currents that parallel the Gulf Stream. Such dispersal patterns would help to account for the occurrence of dark-colored rock- lings in the north and light-colored ones in the south. Rocklings from the Northern Atlantic area more closely resemble fish from Europe and Ice- land in degree of pigmentation and number of vertebrae than they do their immediate neighbors to the south. Conversely they are closer to other North American samples in numbers of pectoral CHARACTER Gulf S. Atl. GEOGRAPHICAL AREA Intermed . N. Atl. Iceland Europe Color Anal Rays Dorsal Rays Vertebrae Pectoral Rays Gill Rakers 6.2 40.2 47.0 51.4 17.2 6. 7 40.8 47.9 51.! 17.2 3.8 42.8 43.5 49.9 50.4 52.8 52.9 16.7 16.S 1.9 1.) 42.6 49.2 FIGL'RE 4. — Summary of means of character states for Enchelyopu^ cimbnus from six geographical areas. Heavy lines are drawn around entries that are discussed in the te.xt as separate entries and that illustrate overall lack of convergence m character states. 97 FISHERY BULLETIN; VOL, 77. NO, 1 rays and gill rakers. Spawning is known to occur in the Northern Atlantic area. Eggs have been taken from surface tows in Passamaquoddy Bay, where spawning peaked at bottom temperatures of 9° to 10°C (Battle 1930). In Long Island Sound eggs were found to be most abundant in the upper 12 m (Williams 1968). In reviewing the natural history of E. cirnbriuK in the Gulf of Maine, Bigelow and Schroeder (1953) mentioned the pos- sibility of planktonic existence as long as 3 mo. Given such a time span, the complex hydrographic regime of the area might occasionally distribute early stages to the south inshore of the Gulf Stream or even more rarely might transport them via the Gulf Stream to the eastern Atlantic. Iceland rocklings are usually light colored, as are fish from the Northern Atlantic and Europe areas. For counts of dorsal and anal fin rays, and vertebrae, Iceland fish have the highest means of all (ignoring the two fish from Africa); perhaps these characters are influenced by temperature, as Iceland has the lowest temperatures of any of the six areas. In numbers of pectoral rays, Iceland and European fish are identical and in gill rakers nearly so, and different from counts of North American ones. Adults at least of the Iceland population may be isolated as Kotthaus and Krefft (1967) did not catch E. cinibritis along the Iceland-Faroe ridge. Enchelyopus cinihrius spawns at least around the southwest coast of Ice- land (Einarsson and Williams 1968). The linear range of the fourbeard rocklingalong the coasts of Europe is about as great as along the coasts of North America. We have examined only a small sample, from southern Scandinavia; hence, it is possible that more variation exists than we have recorded. However, we point out that in our sample the color pattern resembles that of Iceland and Northern Atlantic fish, that counts of anal and dorsal fin rays and vertebrae are lower than those in Iceland, and that in numbers of pectoral fin rays and gill rakers Europe and Iceland fish are more like each other than they are like North American populations. Rocklings are known to spawn in European waters [Svetovidov 1 1973) gives several references]. Enchelyopus cimbrius could have reached Europe from the west via the Gulf Stream system; it seems unlikely that east to west disper- sal is possible. We do not know whether the West Greenland specimen of E. cimbrius represents a breeding population or a stray. The two West African examples are so far re- 98 moved from their nearest known neighbors ( Bay of Biscay ) that we forego conjecture as to their origin. THE GENERA OF ROCKLINGS The rocklings are classified in the subfamily Lotinae of the family Gadidae (Svetovidov 1948) and can be distinguished by the nature of the three dorsal fins, which, although scarcely separated from each other, bear quite different kinds of rays (Figure .5). The first dorsal fin consists of a single, unsegmented ray which is not bilaterally divided (we have examined microscopic sections) and is supported by a strong pterygiophore. The ray is thicker than any others in the dorsal fin and in many species is longer as well. In Enchelyopus cimbrius it is soft, being ossified only proximally. Sharply distinguished from the first and third dor- sal fins is a row of small, unsegmented, bilaterally divided filaments which appear fleshy, although they stain with alizarin. These small rays origi- nate on a compressed ridge that rises from a mid- dorsal groove. Although Bogoljubsky (1908) fol- lowed by Svetovidov ( 1948) did not consider these filaments to be true fin rays they should be consi- dered as such, as examination of an alizarin prep- aration and of sections shows that a simple, os- sified, rod-shaped skeletal support is present for each. The third dorsal fin is composed of ordinary, bilaterally divided, segmented rays, each with a well-developed pterygiophore. A second characteristic of the rocklings is the presence on the snout of prominent barbels ithe closest approach to this character among other gadids being a nasal cirrus in Lota ) in addition to the barbel at the tip of the lower jaw. Thus, the rocklings are distinguished by two specialized characters and can be considered as a distinct tribe of Lotinae, the Gaidropsarini [clas- sified as a distinct family by some, for example, de Buen (1934)]. Although rocklings have been treated under as many as 14 different generic names [see Svetovidov (1973) for synonyms], many ichthyologists (for example, Andriyashev 1954; Norman 1966) follow Svetovidov (1948) in recog- nizing three. More recently, however, five genera have been recognized (Wheeler 1969). How many genera should be recognized and why? In his 1948 treatment of the rocklings, Svetovidov provided diagnoses for the three gen- era that he recognized based on barbel number, skull shape, vomerine tooth patch shape, and COHEN and RUSSO VARIATION IN FOURBEARD ROCKLING 'muiidiiiiiiilM'- r// Fl( ;L'RE 5, — Enchelyopus cimhrius. USNM 217900, standard length 135 mm; photograph of an alizarm preparation m glycerin showing the three different kinds of dorsal fin rays and their skeletal supports. number and distribution of supratemporal pores (our Table 9). Unfortunately, he was unable to study all of the species. We have examined six of the nominal Gaidropsarus species that he recog- nized, both species oiCiliata, and, of course, En- vhelyopus (study material of all genera is listed in the Appendix). Number of barbels is the only character that unequivocally divides our material according to Svetovidov's classification. Proper evaluation of the skull-width character will require the examination of osteological prep- arations, which we have not done. We note, how- ever, that although Ciliata inustela has a notably broad skull, that ofC septentrionalis appears to be narrower. Also, although most species oiGaidrop- Hcinis appear to have narrow skulls, that of G. guttatus appears broad. Regarding the size and shape of the vomerine tooth patch, it is highly variable, and although it may serve to distinguish some species it is of doubtful value at the genus level. Table 9. — Summary of diagnostic characters for three rockling genera given by Svetovidov (1948). Characters Genus and no. No. of Skull Supratemporal of species barbels shape Vomer pores Gaidropsarus 3 Narrow Head large. 3 - 1 pair + 1 (13) apex angular median Enchelyopus 4 Narrow Small 3 - 1 pair + 1 (1) median Ciliata 5 or Broad Head small, 2 - 1 pair (2) more anterior a semicircle Number of supratemporal pores also is a vari- able character. Five of the Gaidropsarus species that we have studied show the pattern given for the genus by Svetovidov (1948), one median and one pair of pores ( = 3). However, G. argentatus has two pairs and no median pores ( = 4). In Ciliata, C. mustela has one pair ( = 2), while C . septentrionalis has three pairs ( = 6). As noted above, Wheeler ( 1969) recognized five genera, the three recognized by Svetovidov (1948): Enchelyopus. CUiata. and Gaidropsarus: and also Onogadus de Buen 19.34; and a genus introduced for the first time, Antonogadus. Onogadus was originally proposed for Gaidrop- sarus ensis, one of the threebeard rocklings, be- cause of its elongate first dorsal ray. Wheeler (in Svetovidov 1973) has subsequently assigned to Onogadus, G. argentatus, a species with a far shorter first dorsal fin ray. We have found the length of the first dorsal fin to be highly variable in Enchelyopus. As presently used, this character does not separate genera. (Wheeler^ has informed us that Onogadus may be differentiated on the basis of vertebral counts. Due to insufficient data we have no comment on this character.) As we have mentioned above, G. argentatus differs from G. ensis and resembles Ciliata in lacking a median supratemporal pore. 'A. Wheeler. Department of Zoology. British Museum (Natural History), Cromwell Road, London S.W. 7. England. Pers. Commun. March 1978. 99 FISHERY BULLETIN VOL 77, NO 1 Antonogadus Wheeler 1969 was first introduced in the combination Anionngaclus macrophthal- mus (Giinther), unfortunately, in a key to species rather than a treatment of genera. Subsequently, another threebeard rockling, Gaidropsarus megalokynodon (Kolombatovic 18941, was refer- red to Antonogadus (Wheeler in Svetovidov 1973) in a checklist. There is no way to tell if the original key characters describing dentition, mouth size, and color are diagnostic of the genus Antonogadus or the species A. macropththalnius; however, we assume that they apply to the genus. Color may be discounted as a generic character as it is highly variable among the species of Gakhvpsarus and varies geographically in the single species of En- chelyopus. Regarding mouth size, Wheeler (1969) noted "mouth large, extending well past eye": however, figures of macrophthalnius given by Gunther [1867, pi. 5, fig. B and 1887, pi. 42, fig. D. the latter as Onus carpenteri, a junior synonym of mac!-ophthalmus according to Wheeler in Svetovidov (1973)] show fish with small mouths. The second species referred to Antonogadus. megalokynodon, is figured by Soljan ( 1963) as hav- ing a large and capacious mouth, but he shows the same condition for several other species of threebeard rocklings. So far as we can tell mouth size is not a useful generic character. Carrying on to dentition, Wheeler (1969) noted, "A pair of large, fang-like, teeth (sometimes three or four) in front of the upper jaw." If Antonogadus is recog- nized on the basis of such a character then it would be necessary to place the two species of Ciliata in separate genera, as C. mustela, the type-species of the genus has bands of equal-sized teeth in the upper and lower jaws, while C. septcntrionalis has in addition to these bands a much enlarged outer row of teeth in the upper jaw and an enlarged inner row in the lower jaw. It is by no means clear that number of barbels alone divides the rocklings into natural species assemblages; convergence may have occurred and other groupings based on different characters may produce a phyletically more correct classification. Obviously, thorough study and a careful analysis of characters is required. For the present there seems insufficient information available to do other than recognize on the basis of number of barbels a single genus with three subgenera, or three genera. We follow the latter course as it is the most conservative in terms of the present usage of names. We recommend therefore, that for the present Onogadus be relegated once again to the synonymy of Gaidropsarus where it should be joined by Antonogadus. THE CORRECT GENERIC NAME FOR THE FOURBEARD ROCKLING Although differences at the species level have not evolved in populations of the fourbeard rock- ling on both sides of the North Atlantic, curiously enough geographical isolation seems to have af- fected the evolution of different generic names. Rhinoncinus is used by European ichthyologists (see, fore.xample, Svetovidov 1973); North Ameri- can ichthyologists use Enrhelyopus (see, for example, Leim and Scott 1966). Which is the cor- rect name? Enchelyopus Gronovius 1760 was the first of the two names proposed. Although only a brief color description was given, reference was made to the same author's pre-Linnean Museum Ichthyo- logicum published in 1754, in which work under the names Mustela vivipera and viviparous eelpout is presented a recognizable description of the species presently named Zoanvs viviparus (Linnaeus). This identification is further verified by a Gronovius specimen still extant in the British Museum, which Wheeler ( 1958) has suggested is a type-specimen of Blennius viviparus Linnaeus. Use of Enchelyopus in Zoarcidae, where it is a senior synonym of Zoarces Cuvier 1829 has been accepted by Norman (1966) and noted as being correct by Andriyashev (1973). Some ichthyologists (Gill 1863b;Jordan 1917), however, seem to have overlooked Gronovius ( 1760) and at- tributed the name to Gronovius (1763) in his Zoophylaceum, a work subsequently ruled on by the International Commission on Zoological Nomenclature (Opinion 89) as being unavailable for purposes of zoological nomenclature. The Commission noted in its ruling that combinations used in the Zoophylaceum were "binary" though not "binomial," which interpretation complied with the then current edition of the Rules, and the work was declared unavailable by suspension of the Rules. Although Gronovius (1760) never has been ruled on by the Commission it follows the same system of nomenclature as does Gronovius (1763) and clearly is not binominal. The same is true of Gronovius (1762), which has been rejected (Opin- ion 332). Under the provisions of the present Code (Article 11(c)), names published in Gronovius ( 1 760) are not available as the author did not con- 100 COHEN and RUSSO VARIATION IN FOURBEARD ROCKLING sistently apply the principles of binominal nomenclature. Although Article ll.(c)(i) ("Uni- nominal genus-group names published before 1931 without associated nominal species are ac- cepted as consistent with the prmciples of binomi- nal nomenclature, in the absence of evidence to the contrary.") might serve as a basis for arguing that the names in Gronovius ( 1760) are available, the interests of stability would be served best by considering the work unavailable, as its accep- tance would require not only that Enchelyopiis Gronovius 1760 replace Zoarceg Cuvier 1829, but also that Cyclogaster Gronovius 1760 replace Liparis Scopoli 1777. If Gronovius (1760) is considered as unavailable for purposes of zoological nomenclature then the first valid use of Enchelyapus is by Bloch and Schneider (1801). The type-species was stated by Jordan (1917) as Gadus cimbrius Linnaeus 1766 as first restricted, and Svetovidov (1973) gave the type as Gadus cimbrius Linnaeus 1766 by monotypy. However, neither of these methods of type fixation is correct as Bloch and Schneider referred 12 species to the genus, and although cimbriua is the first one in order, there is no action that could be construed as a type designation. The earliest type designation for Enchelynpus Bloch and Schneider 1801 that we have been able to find is that of Jordan (1917) as Gadus cinibrius Lin- naeus 1766. Rhinonemus Gill (1863a) was proposed for Motella vaudavuta Storer 1848, a junior synonym of Gadus cimbrius Linnaeus (Goode and Bean 1879) and is therefore a junior synonym of En- chelyopus Bloch and Schneider. ACKNOWLEDGMENTS We are grateful to A. Wheeler for information and discussions about rockling taxonomy, P. Szarek for allowing us to read her unpublished manuscript, and S. Johnson for information on zoarcid nomenclature. For reading and comment- ing on all or part of the manuscript we thank A. Cohen. B. Collette, L. Dempster. M. Fahay, and W. I. Follett. G. S. Myers assisted by allowing access to rare literature. For access to study material we thank D. McAllister, National Museums of Canada; R. Jenkins, Cornell University; J. Kaylor, NMFS, NCAA, Gloucester, Mass.; M. Dick, Harvard University; R. Wigley, NMFS, NCAA, Woods Hole, Mass.; C. Wenner and J. Musick, Virginia Institute of Marine Science; G. Jonsson, Marine Research Institute, Reykjavik; J. G. Nielsen. University of Copenhagen; A. Wheeler. British Museum (Natural History); and M. L. Bauchot, Natural History Museum. Paris. For assistance with computer processing we thank K. K. Beach, E. M. Hamilton, and the Office of Technical Assistance at The George Washington University Center for Academic and Administra- tive Computing. Figures 1-4 were prepared by Keiko Hiratsuka Moore. George Clipper took X-ray photographs. Histological sections of the dorsal fin were prepared by Margaret Melville. The manuscript was typed by A. McClain and V. Tucker. LITERATURE CITED ANDRIYASHEV, A. P. 1954. Ryby severnykh moryei SSSR. Opred. Faune SSSR53,566p,Akad.Naul5SSSR, iTransl 1964, Fishes of the northern seas of the U.S.S.R. Keys to the fauna of the U.S.S.R. 53. 617 p.. U.S. Dep. Commer,, Natl.Tech. Inf. Serv., Springfield. Va. OTS 63-11160.1 1973. Zoarcidae. In J C. Hureau and Th Monod (editorsi. Check-list of the fishes of the north-eastern At- lantic and of the Mediterranean. Vol. I, p. 540-547. UN- ESCO. Pans. Battle, H. I. 1930. Spawning periodicity and embryonic death rate of Enchelynpus cimhrws iL.) m Passamaquoddy bay. Con- trib. Can. Biol. Fish., New Ser. 5:363-380. BICELOW, H. B., AND W. C. SCHROEDER. 1953. Fishes of the Gulf of Maine. U.S. Fish Wildl. Serv., Fish. Bull. 53. 577 p. BLOCH, M. E.. AND J, G. SCHNEIDER. 1801. Systema Ichthyologiae. Berlin, 584 p. BOGOLJUBSKY, S. 1908. Zur kenntnis der dorsalflosse bei "Motella tricirra- ta". Z. Wiss. Zool. 90:327-333. BUEN, F. DE. 1934. Notas sobre los Gaidropsaridae fPeces). Un nuevo genero \Onogadus nov. gen.) y una nueva especie [Gaid- rupsarus barbatiis nov. sp.l. Bol, Soc, Esp. Hist. Nat. 34:499-504. BULLIS, H. R., JR., AND J. R. THOMPSON. 1965. Collections by the exploratory fishing vessels Ore- gon. Silver Bay. Combat, and Pelican made during 1956 to 1960 in the southwestern North Atlantic, U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 510. 130 p, CUVIER, G. 1829. Le regne animal, Nouvelle ed, torn, II. Paris, 406 p, DV BUIT, M. H. 1968. Notes biometriques et biogeographiques ser deux pois.sons teleosteens consideres comme rares dans 1' Atlan- tique Nord. Trav. Fac. Sci. ser Oceanogr. Biol. Univ. Rennes 1:15-17. EINARSSON. H., AND G. C. WILLIAMS. 1968. Planktonic fish eggs of Faxafloi. southwest Iceland, 1948-1957. Hit Fiskideildar 4i5l. 15 p. 101 FISHERY BULLETIN VOL. 77. NO 1 Gill, T. N. 1863a. Synopsis of the North American gadoid fishes. Proc. Acad. Nat. Sci. Phila. 1863:229-242. 1863b. S.vnopsis of the family Lycodoidae. Proc. Acad. Nat. Sci. Phila. 1863:254-262. GINSBURG, I. 1952. Eight new fishes from the Gulf coast of the United States, with two new genera and notes on geographic distribution. J. Wash. Acad. Sci. 42:84-101. GOODE. G. B., AND T. H. BE.\N. 1879. The identity oi Rhinonemus caudacuta (Storer) Gill with Gadus ctmbnus, Linn. Proc. U.S. Natl. Mus. 1:348-349. 1896 (1895). Oceanic ichthyology. U.S. Natl. Mus. Spec. Bull. 2, 551 p. Gronovius, L. T. 1754. Museum Ichthyologicum, sistens piscium indi- genorum et quorundam exoticorum, qui in Museo Laur. Theod. Gronovii. adservantur. descriptiones. ordine sys- tematico; accedunt nonnullorum exoticorum piscium icones, aeri incisae, vol. 1. Lugduni, 70 p. 1760. Animalium in Belgio habitantium centuria pri- ma. Acta Helv. 4:243-270. 1762. Animalium Belgicorum observatorum centuria quinta. Acta Helv. 5:353-382. 1763. Zoophylacii Gronoviani. fasc. 1. Leiden, 136 p. Gunther, a. 1867. Additions to the British fauna, Ann. Mag. Nat. Hist.,Ser. 3, 20:288-291. 1887. Report on the deep-sea fishes collected by H.M.S. Challenger during the years 1873-76. Zoology of the Challenger Expedition. Part 57, 335 p. JOENSEN, J. S., AND A. V. TAANING. 1970. Marine and freshwater fishes. In S. L. Tuxen (editor). Zoology of the Faroes, 241 p. Vald. Pedersen, Copenh. Jordan. D. S. 1917. The genera of fishes, pt. I. Stanford Univ. Publ. Univ. Ser. 27:1-161. KOTTHAU-S. A., AND G. KREFFT. 1967. Observations on the distribution of demersal fish on the Iceland-Faroe Ridge in relation to bottom tempera- tures and depths. Rapp. P -V. Reun. Cons. Perm. Int. Explor. Mer 157:238-267. LEIM, A. H., AND W. B. SCOTT. 1966. Fishes of the Atlantic coast of Canada. Fish. Res. Board Can. Bull. 155, 485 p. LINNAEUS, C. 1766. Systema Naturae. Tom. 1, 12th ed. Holmiae. 532 p. Norman, J. R. 1966 A draft synopsis of the orders, families and genera of recent fishes and fish-like vertebrates. Br. Mus. (Nat. Hist.), Lond., 649 p. SAEMUNDSSON, B. 1949. Marine Pisces. In A. Friorikssen and S. L. Tuxen (editors). The zoology of Iceland, 4(72), 150 p. Munksgaard, Copenh. and Reyk. SCOPOLI, J. A. 1777. Introductio ad histonam naturalem. Pragae, 506 p. s6ljan,T. 1963. Fishes of the Adriatic. Revised Engl. ed. NOLIT, Belgr., 428 p. SVETOVIDOV, A. N. 1948. Treskoobraznye. Faune SSSR, Ryby 9(4), 221 p. Akad. Nauk SSSR. (Transl. 1962, Gadiformes, Fauna USSR, Fishes 9(4i, 304 p. U.S. Dep. Commer., Natl. Tech. Inf Serv., Springfield, Va. OTS 63-11071.) 1973. Gadidae. /n J. C. Hureau and Th Monod (editors). Check-list of the fishes of the north-eastern Atlantic and of the Mediterranean, Vol. I, p. 303-320. UNESCO, Paris. TYLER, A. V. 1971 . Periodic and resident components in communities of Atlantic fishes. J. Fish. Res. Board Can. 28:935-946. WHEELER, A. C. 1958. The Gronovius fish collection: a catalogue and his- torical account. Bull. Br. Mus. (Nat. Hist.) Hist. Ser. 1:187-249. 1969. The fishes of the British Isles and North-West Europe. Macmillan, Lond., Melb.. Toronto, 613 p. Williams, G. C. 1968. Bathymetric distribution of planktonic fish eggs in Long Island Sound. Limnol. Oceanogr. 13:382-385. Zar, J. H. 1974. Biostatistical analysis. Prentice Hall Inc., En- glewood Cliffs, N.J., 620 p. 102 COHEN and RUSSO: VARIATION IN FOIIRBEARD ROCKLING APPENDIX The following abbreviations indicate institu- tions or collections: CU, Cornell University; MCZ. Museum of Comparative Zoology, Harvard Uni- versity: MNHN, Museum National d'Histoire Naturelle, Pans: NEFC, Northeast Fisheries Center, Woods Hole, Mass.; NMC, National Museum of Natural Sciences, Ottawa: USNM, Na- tional Museum of Natural History, Washington. D.C.; ZMUC, Zoologisk Museum, Copenhagen. The "Intermediate" region, below, extends from about lat. 35"N to about lat. 37°N in the western Atlantic. Enchelyoptis cimhriin GULF OF MEXICO— USNM 190346 (3 speci- mens), Si/wrSavstn 294, 27°54'N,95°23'W, 79m. USNM 217843 (16), Oregon 3724, 29°04'N, 88°31'W, 403 m. USNM 217939 (1), Oregon .5795, 24'16'N. 82'30'W, 439 m. SOUTHERN ATLANTIC— USNM 217923 (2), Silver Bay 1611, 29°06'N, 80°00'W, 339-384 m. USNM 217924 (2), Silver Bay 223, 29°14'N, 80°05'W, 247 m. USNM 217935 (1), Oregon 5798, 29n4'N, 80°05'W, 357 m. USNM 217933 (5). Ore- gon 5098, 29°17'N, 80°05'W, 379 m. USNM 217931 (1), Silver Bay 4227, 29°20'N, 80°05'W, 348 m. USNM 217949 ( 2 ), Silver Bay 224, 29°29'N, 80°09'W, 329 m. USNM 217937 (1), Combat 475, 29^30 'N, 80°10'W. 293 m. USNM 217934 (3) Ore- gon 5093, 29''31'N, 80'=09'W, 384 m. USNM 217932 ( 1 ), Silver Bay 219, 29°34'N, 80°09'W, 348 m. USNM 217917 (1), Silver Bay 1607, 29°34'N, 80°09'W, 371 m. USNM 217943 (1). Combat 325, 29'35'N, 80°10'W, 366 m. USNM 217936 (1), Combat 314, 29°38'N, 80°11'W, 329 m. USNM 217918 ( 1 ), Oregon 5238, 29°39'N, 80°12'W, 348 m. USNM 217916 (2), Silver Bay 1606, 29°40'N, 80°12'W, 348 m. USNM 217940 (1), Silver Bay 217, 29°41'N, 80°08'W, 348 m. USNM 2~17919 (2), Silver Bay 458, 29°49'N, SO'IO'W, 220 m. USNM 217921 (2), Silver Bay 1552, 29°43'N, 80°12'W, 302 m. USNM 217948 (1), Combat 435, 29°46'N, 80"12'W. 366 m, USNM 217920 (1), Silver Bay 3742, 29"50'N, 80'13'W, 275 m. USNM 217950 (5i, Silver Bay 1604, 29°50 'N, 80°10 'W, 302 m. USNM 217947 (2), Silver Bay 3678, 29''53'N. 80ni'W, 329 m. USNM 217944 (3), Silver Ba\ 3675, 29°55'N, 80'1 1 'W, 329 m. USNM 217922 ( 1 ) Silver Bay 4367, 29°55'N, 80°11'W, 320m. USNM 217945 (1), Oregon il), 5233, 29°54'N, 80°10'W, 348 m. USNM 217925 il). Combat 471, 29°57'N. 80°12'W,329m.USNM217946(3),Pe/(co/! 182-8, 32''09'N, 79°02'W, 275 m. USNM 217938 (1), Combat 300, 32°15'N, 78°51'W, 348 m. USNM 217927 ( 1 ), Combat 289, 33°03 'N, 77°09'W, 366 m. INTERMEDIATE— USNM 45898 (1), A/6o- /ms.s-.35°40'N,74'52'W. USNM 45895-6 (7), A/6o- tross. 36°02'N, 74°48'W. USNM 217941 (1), Ore- gon II 10763, 36°01'N, 74=48'W, 311-567 m. USNM 217951 (1), Oregon II 10664, 36°12'N, 74^47 'W, 249-329 m. USNM 217942 (2), Oregon II 10724, 36°14'N, 74"45'W, 366-421 m. USNM 217929 (2), Columbus helm 73-10-40, 36°33'N, 74°42'W, 296 m. USNM 217928 (3), Columbus Iselin 73-10-47, 36°37'N, 74°42'W, 316 m. USNM 217926 (3), Columbus Iselin 73-10-89, 37°02'N, 74°38'W, 367 m. USNM 217930 (7), Columbus Iselm 73-10-73, 37'05'N, 74''43'W, 194-479 m. NORTHERN ATLANTIC— USNM 28994 (1), Albatross. 38'39'N,73n 1 'W, 238 m. USNM 45969 (1), Albatross, 38°54'N, 72°51'W. USNM 28917 (li, 39°43'N, 7r32'W. USNM 45891 (1), A/6o- //w,s, 39°48'N, 71°49'W. MCZ 37492 ( 1 ), Capt. Bill II 20, 39°57'N, 7r07'W, 412 m. USNM 28843 (1), Fish Haivk, 39°57'N, 70°32'W. USNM 28816 H), 39°N, 7rW. MCZ 38039 (1), Caryn 3-1, 39°59'N, 70'48'W, 381 m. USNM 33352 il ), Fish Hawk, 40°20'N, 70°35'W. USNM 28709 il), 40°24'N, 70°42'W. USNM 35680 (1), 40°21'N, 70°29'W. USNM 28890 (2). 40°28'N, 70°44'W. USNM 126948 (1), Fish Hawk, Long Island Sound, 22 m. USNMuncat.ll),A/6a^roi;,s/V,4ri4'N,71°41'W. USNM 213501 (7), Blesk 68-18, 22-01, 4r52'N, 68°12'W, 198 m. USNM uncat. (1), Blesk 68-18, 24-02, 41°36'N,68''52'W, 138 m. USNM uncat.(l), Blesk 68-18, 28-01, 42°N, 69°39'W, 210 m. USNM 16656 ( 1 ), Woods Hole. Mass. CU 18353 ^'i). Alba- tross HI 27-45, 41"53'N, 69°10'W, 212 m. USNM uncat. (1), Delaware 60-1-11, 4r52'N, 68n4'W, 227 m. CU 18274 ( 1 ). Albatross III 61-1, 4r49'N, 68°14'W, 154 m. USNM 23761 (1), Prov- incetown, Mass. CU 45869 ( 1 ), Albatross IV 63-5- 69, 42'07'N, 67°3rW. NEFC uncat. (3), Albatross III 70-23, 42°10'N, 68°38'W, 183 m. NEFC uncat. (1), Albatross III 101-103, 42°15'N, 67°10'W, 168 m. CU 23620 (3), Albatross III 27-55, 42°41'N, 69°49'W, 256 m. NEFC uncat. (1), Albatross HI 47B-3-2, 42^41 'N, 70"09'W, 84-139 m. USNM 839251 1 ). Mass. Bay. USNM 2 1918 (I ). .Mass. Bay, 103 134 m. USNM 131920 (6), Mass. Bay. USNM 21918-9 (2), Mass. Bay. MCZ 34614 (3), 42°56'N, 70°18'W, 165 m. MCZ 34611 (3), Albatross II. 43°07'N. TOMO'W, 154 m. USNM 37847 (1 i, Ipswich Bay. Ma.ss. MCZ 34612 (9), Alhutmss II, 43°03'N, 76°09'W. USNM 45897 (1), Albatross. 43°34'N, 63°56'W. MCZ 34613 (4), 43°39'N, 68°12'W. 192 m. MCZ 12340 ( 1 ), Eastport, Maine. USNM 39060 (1), Prince Edward Island. USNM 43229 tl), 47°15'N, 53°58'W. NMC 63-151 (li, 51"28'N, 53°52'W. GREENLAND— ZMUC uncat. (1), Adolf Jen- sen 4420, 64°22'N. 52°54'W, 460-540 m. ICELAND— ZMUC 95-96, (2), North coast of Iceland, ca. 66°N, 18°30'W. ZMUC 830-32 (3), Vestman Islands. ZMUC 26-27 (2), 63°46'N. 22°56'W. ZMUC P379 ( 1 ). south of Iceland. USNM 217909 (1), 65°37'N, 2r00'W. 110 m. USNM 217911 (1), 65°41'N, 2r20'W, 137-152 m. EUROPE— USNM 39724 ( 1 ), Denmark. ZMUC 84-85 (2), 90-93 (4), 501, 503-4 (3), P37284-292 (9), P37294-96 (3), P37298 (1), Denmark. ZMUC P37283 (U, Limfjord, Denmark. P37297 1 1). Kal- lundbors Fjord, Denmark. ZMUC 88 1 1 I. 502 1 1 I. Snekkersten. Denmark. ZMUC 86 ill, 98 (li, Oresund, Denmark. ZMUC 22-23 (2), Skagerak, 200 m. ZMUC 25 (1), off Lindesnds. Norway, 220 m. USNM 44514 (li, Drobak, Norway. AFRICA— MNHN 38-110/111 (2i, off Cape Blanc, Mauritania. Ciliata imntcla USNM 130840 (4). Europe. USNM 44510 (1), Norway. USNM 216711 (2), Oresund, Denmark. FISHERY BULLETIN VOL. 77, NO. 1 cm at a septentriona lis ZMUC 371656-7 i2i, Faroe Islands. Ga idropsa riis a rgeu tutu .v MCZ 38353,38387 (2), western North Atlantic. USNM 217907 (1), Iceland. USNM 217912 (1), Iceland. USNM 217910 (1), Spitsbergen. USNM 217908(2). Iceland. Gil /(Jruf) iiirm e n .v is MCZ 37554 111, we.stern North Atlantic. MCZ 27882 1 1 1, western North Atlantic. MCZ 38425 ( 1 1, western North Atlantic. MCZ uncat. I li. western North Atlantic. USNM 217913 1 1 1, western North Atlantic. GaidropSiirns iiiittutin USNM uncat. i2i. ill, (5i, San Miguel Island, Azores. Gaidropscinis tuediterraneiis USNM uncat. ill, Tunisia. Ga idropsa rns t ii /ga ris USNM uncat. ( 1 ), 1 1 1, l3i, Tunsia. Gaidropsanis sp, USNM uncat. l5i, Amsterdam Island. 104 EARLY DEVELOPMENT OF SEVEN FLATFISHES OF THE EASTERN NORTH PACIFIC WITH HEAVILY PIGMENTED LARVAE (PISCES, PLEURONECTIFORMES) B. Y. SuMiDA, E. H. Ahijstrom, and H. G. Moser' ABSTRACT Eggs and larval series are described for six species of flatfishes occurring off California with heavily pigmented larvae. These are the pleuronectids Pleuronichthys coenosus, P decurrens, P. ntteri, P. verticalis. and Hypsopselta guttulata and the bothid. Hippoglossina stomata. A brief description of postflexion larvae of the Gulf of California species. P ocellatus, is also presented. Eggs of Pleuronichthys are unusual among flatfishes in possessing a sculptured chorion composed of a network of polygonal walls, whereas the chonons of Hypsopsetta guttulata and Hippoglossina stomata eggs are smooth and unomamented. Eggs o{ Hypsopsetta guttulata and P. ritteri are unusual among those of pleuronectid flatfishes in possessing an oil globule. A combmation of pigmentation, morphology, and meristics can distinguish the seven species of flatfishes with heavily pigmented larvae. Larvae of two species, H guttulata and P. decurrens, have a distinctive pterotic spine on either side of the head. Sizes at hatching, at fin formation, and at transformation are important considerations to distinguish these species. Meristic counts, particularly of precaudal and caudal groups of vertebrae, are important to relate a larval series to itsjuvenile and adult stages and thus substantiate identification of the series. This report deals primarily with the eggs, larvae, and early juveniles of flatfishes of the genus Pleuronichthys. Descriptions are included for complete series of larvae of four species, P. decur- rens (curlfin turbot),* P. coenosus (C-0 turbot), P. verticalis (hornyhead turbot), and P. ritteri (spot- ted turbot). A brief account of postflexion larvae of the Gulf of California species, P. ocellatus (Gulf turbot), is also given. Larvae of Pleuronichthys are heavily pigmented, even at hatching, as are those of the pleuronectid, Hypsopsetta guttulata (diamond turbot), and the bothid, Hippoglossina stomata (bigmouth sole). To identify heavily pig- mented flatfish larvae obtained in plankton collec- tions from the eastern North Pacific, it is neces- sary to know the larval developmental, series of all of the above species. These species comprise minor incidental catches within California commercial and sport fisheries and are reported as a general 'Southwest Fisheries Center La JoUa Laboratory. National Marine Fisheries Service. NOAA. P.O. Box 271. La Jolla. CA 92038. ^The common name turbot is used for all species of Pleuronichthys. a usage consistent with Fitch ( 1963). Miller and Lea (1972). and Gates and Frey (1974:79). The American Fisheries Society's list of common names (Bailey et al. 1970) designates P. coenosus and P decurrens as soles, but we disagree with giving species within a genus different common general names. Manuscnpt accepted September 1978. FISHERY BUIXETIN VOL. 77, NO. 1, 1979. grouping of "turbots." Species most commonly caught in the fisheries are P. decurrens. P. coenosus, P. verticalis, and Hypsopsetta guttulata (Frey 1971; Bell 1971; Oliphant 1973; Pinkas 1974; McAllister 1975). No specific catch data are available for Hippoglossina stomata, but the species is probably caught incidentally and in- cluded in the "miscellaneous sole" category of catch data. In a review of the genus Pleuronichthys, Fitch (1963) recognized six species including the five listed above and P. cornutus from off Japan and China. In an earlier review of the genus, Starks and Thompson ( 1910) recognized these six species and P. nephelus Starks and Thompson. Norman (1934) concurred with Starks and Thompson in recognizing seven species. Fitch (1963), however, agreed with Hubbs (1928) in finding no grounds for the separation of P. nephelus from P. coenosus after his examination of the type material of P. nephelus. Fitch's review is thorough; he examined more than 5,700 individuals of the genus. We fol- low his classification. The first descriptions of the eggs and early-stage larvae of Pleuronichthys were given by Budd (1940) who dealt with P. coenosus, P. decurrens. and P. verticalis. Orton and Limbaugh (1953) de- scribed the eggs of Hypsopsetta guttulata and P. 105 FISHERY BULLETIN VOL 77. NO. 1 ritteri. Larvae of P. verticalis were illustrated in Ahlstrom and Moser (1975), and Eldridge (1975) described and illustrated larvae of//, guttulata. MATERIALS AND METHODS Eggs, larvae, and somejuveniles were primarily obtained from California Cooperative Oceanic Fisheries Investigations (CalCOFI) collections. These samples were preserved in a consistent manner as described in Kramer etal.( 1972). Addi- tional material was obtained from bay, estuarine, and coastal collections of Occidental College; Southwest Fisheries Center Tiburon Laboratory, National Marine Fisheries Service; California State University at Fullerton; Scripps Institution of Oceanography; Oregon State University; and Humboldt State University. Specimens of P. rit- teri, P. verticalis, and H. guttulata reared at the Southwest Fisheries Center La Jolla Laboratory, National Marine Fisheries Service, were also utilized. Egg and oil globule diameters were measured using an ocular micrometer in a stereomicroscope. For eggs that were not perfectly round, the greatest diameter was recorded. Scanning elec- tronmicrographs were made for four kinds of Pleuroniehthys eggs and for eggs of Sy nodus lucioceps (Synodontidae). The greatest diameter of 10 randomly selected polygonal facets of the chorion of Pleuronichthys and Synodus eggs were measured using an ocular micrometer in a com- pound microscope. To do this the chorion was cut into pieces that were laid flat on a glass slide with a cover slip over them. The number of specimens examined varied by species, depending on their availability and abun- dance, ranging from several hundred larvae of P. verticalis, the most abundant species, to two lar- vae of P. ocel lotus. For most species, the minimum number of specimens studied is indicated in the morphometric tables with usually twice as much material looked at for pigmentation development. A developmental series of larvae through juveniles was assembled for each species. Mea- surements of selected body parts were taken to provide descriptive and comparative morphomet- ric data. Measurements were made on the right side of each pleuronectid specimen, and on the left side of the bothid, Hippoglossina stomata, using an ocular micrometer in a stereomicroscope. Ter- minology used in the morphometric tables is as follows: Body length = In preflexion and flexion stages, horizontal distance from tip of snout to tip of notochord, referred to as notochord length (NL); in postflexion stages, from tip of snout to posterior margin of hypural elements, i.e., standard length (SL). Snout to anus = Horizontal distance from tip of snout through midline of body to vertical through anus. Head length = Horizontal distance from tip of snout through midline of head to margin of cleithrum preceding the pectoral fin base. Snout length = Horizontal distance from tip of snout to anterior margin of pigmented re- gion of eye. Eye width = Horizontal distance through midline of pigmented eye. Eye height = Vertical distance through center of pigmented eye. Body depth at pectoral base = Vertical distance across body at pectoral fin base prior to for- mation of dorsal fin pterygiophores. An as- terisk follows this measurement in the mor- phometric tables when it includes the depth of dorsal fin pterygiophores. Body depth at anus = Vertical distance across body at anus prior to formation of dorsal fin pterygiophores. An asterisk follows this measurement when it includes the depth of the dorsal fin pterygiophores. Caudal peduncle depth = Vertical distance across tail immediately posterior to terminal dor- sal and anal fin rays. Caudal peduncle length = Medial horizontal dis- tance from vertical through terminal dorsal and anal fin rays to posterior margin of hypural elements. Snout to pelvic fin origin = Horizontal distance from tip of snout to vertical through origin of right pelvic fin (left in H. stomata). Larval specimens for each species were not available in sufficient numbers to clear and stain for complete data on meristics and sequence of ossification of bony elements. However, fin ray counts were made and tabulated on unstained specimens. A partial larval series of P. verticalis, our most abundant species, was cleared with KOH and stained with Alizarin Red-S by Hollister's method (1934) to determine the process of axial skeletal development and fin formation. In addi- tion, several larvae of P. coenosus and P. decur- rens were cleared and stained for precaudal and 106 SUMIDA ET AL EARLY DEVELOPMENT OF SEVEN FLATFISHES total vertebral counts which verified identifica- tions and proved that Budd (1940) confused iden- tifications of larvae of these two species. Radio- graphs of transforming larvae, juveniles, and adults of each species provided additional meristic data. We divide the larval period into three stages, preflexion, flexion, and postflexion, based on the flexion of the notochord which occurs during caudal fin formation (Moser and Ahlstrom 1970; Ahlstrom et al. 1976; Moser et al. 1977). In Pleuronichthys and some other flatfishes the initi- ation of caudal fin formation begins while the notochord is still straight, in the late preflexion stage; we designate this phase as "early caudal formation." We found it convenient to divide the flexion stage into three substages, early flexion, midflexion, and late flexion, dependent upon the state of flexion of the notochord. In the early flex- ion stage, the notochord is very slightly flexed upward; in midflexion, it is flexed midway (nearly a 45° angle); and in late flexion, the notochord is approaching a terminal position, except that the caudal rays remain in a slightly oblique position. Transformation from the larval to juvenile stage was marked by eye migration, development of os- sified pectoral fin rays, scales, and the lateral line. MERISTIC COUNTS OF LARVAE Meristic counts overlap among species consid- ered here, and for discrimination of species it is necessary to use a combination of counts (Table 1). Precaudal and caudal vertebral counts, used in conjunction with dorsal and anal fin counts, are of most use in relating larvae to juveniles or adults. Pelvic fin ray counts are six per side in all seven species and branchiostegal ray counts are seven per side. Pectoral fin counts cannot be made on larvae since ossified pectoral rays form at metamorphosis. Gill rakers are not fully formed during the larval period in the species described. DESCRIPTION OF EGGS Pleuronichthys spp. Eggs of three Pleuronichthys species were first described by Budd (1940) who collected them in plankton hauls from Monterey Bay, Calif. Budd noted the hexagonal patterns on the chorions of Pleuronichthys eggs. This type of ornamentation of the egg shell is confined to Pleuronichthys among flatfishes, but similar polygonal sculptur- ing is found on eggs of the families Synodontidae (Sanzo 1915; Mito 1961) and Callionymidae (Holt 1893; Ehrenbaum 1905; Mito 1962) and in a more exaggerated form on eggs of the sternoptychid, Maurolicus muelleri (Sanzo 1931; Mito 1961). and the macrourid, Coelorhynchus coelorhynchus (Sanzo 1933). Eggs of the three species of Pleuronichthys described by Budd were strikingly different in size; his largest, P. coenosus, averaged 1.88 mm in diameter, his intermediate-sized egg, P. decurrens , 1.44 mm, and his smallest, P. ver- ticalis, 1.07 mm. All had homogeneous yolk, and lacked an oil globule. Our work shows that Budd misidentified the two larger eggs and correspond- ing larvae; the one he called P. coenosus is P. decurrens and vice versa. Orton and Limbaugh 1 1953) described an egg with an hexagonal pattern on its chorion that possessed a single oil globule; they tentatively, but correctly, assigned it to P. ritteri. White ( 1977) illustrated a developing egg of P. ritteri from Newport Bay, Calif Information concerning egg diameters, pres- ence or absence of an oil globule, and character of the chorion are given in Table 2 for six of the seven species treated in this paper. Egg diameters do not change noticeably with the duration of preserva- tion, although some shrinkage is known at the initial time of preservation. There is no overlap in egg size for the three species of Pleuronichthys that lack an oil globule. Eggs of P. decurrens range from 1.84 to 2.08 mm; those of P. coenosus, from Table l. — Meristics of the seven species of flatfishes in the eastern North Pacific that have heavily pigmented larvae.' Pectoral Caudal rays (eyed side) Species rays rays Precaudal Caudal Total giK rakers Total Branched Pleuronichthys decurrens 67-81 46-55 10-14 14-15 24-26 38-41 9-12 79-21 12-15(73) P coenosus 66-78 44-56 9-12 12-73 24-26 37-39 11-15 1 8-20{ 1 91 12-15(73) P verticals 66-79 44-51 10-12 13 23-25 36-38 9-11 79-20 12-14(73) P ocellatus 62-74 44-53 10-12 12-13 22-24 34-36 10-14 19 12-15(73) P rinen 62-72 43-52 9-11 72-13 22-24 34-36 12-17 18-79 73-14 Hypsopsetta gunutata 65-75 47-55 11-13 11-72 22-24 34-36 7+^(5-6) 79-20 13 Hippoglossina stomata 63-70 47-55 11-12 IJ 26-28 37-39 15-21 17'2-)8t 11-73 'Menstics compiled in Table 1 are derived in partfrom literature, particularly Fitch (1963). Norman (1934), Townsend (1936). Clothier (1950). and Ginsburg (1952), and m part from our onginal counts Where a range is given and one count is predominant, that count is italicized ^Lower limb count only 107 FISHERY BULLETIN VOL 77, NO, 1 Table 2, — Measurements of eggs of Pleuronichthy^ species, Hypsopsetta guttulata, and HippogLossina stomata, including Synodus lucioceps for comparative data. Oil globule diameters No 0( Egg diameters (mm) (mm) Species o( chorion measured samples Range Mean SD Range Mean SD Pleuronichthys decurrens Sculptured 41 28 1 84-2 08 1,97 058 P coenosus (CalCOFI) Sculptured 20 15 1 28-1 56 1 47 0066 — — — P coenosus (King Harbor) Sculptured 287 2 1 20-1 42 1 29 0047 — — — P. verticatis Sculptured 188 19 1 00-1 16 1.09 0040 — — — P rinen Sculptured 82 13 94-1 08 1 01 0029 008-0 14 10 009 Hypsopsetta guttulata Smooth 35 4 78-0 89 0,84 0027 12-0 14 13 010 Hippoglossina stomata Smooth 26 9 1 22-1 38 1,29 0,045 0,20-0 26 23 0018 Synodus lucioceps Sculptured 168 8 1 20-1 48 1,32 0049 — — — 1.20 to 1.56 mm; and those of P. uerticalis, from 1.00 to 1.16 mm. Although eggs of P. ritteri, rang- ing in diameter from 0.94 to 1.08 mm, fall within the size range of P. verticalis. they can be readily distinguished by the presence of a small oil globule, 0.08-0. 14 mm in diameter. Eggs of P. ocel- latus were unavailable. Differences in mean diameter of P. coenosus eggs were noted by locality, with eggs taken in open waters off the coast having a larger mean diameter and standard deviation (Table 2, Cal- COFI collections) than eggs sampled from the inlet of a small, shallow, manmade harbor near a power plant discharge (Table 2, King Harbor sam- ples). Except that they are often slightly larger in size, early- and middle-stage eggs of P. coenosus are difficult to differentiate from Synodus lucioceps eggs. They can be separated, however, by careful examination of the size and arrangement of polygons on the chorion. The mean of the greatest distance across polygons (sample size = 200 polygons) on P. coenosus eggs is 0.035 mm in contrast to 0.047 mm for S. lucioceps eggs (Table 3). Furthermore, the polygons on P. coenosus eggs are more regular in arrangement than on S. lucioceps eggs (Figure 1). This more uniform compacting of smaller polygons on P. coenosus eggs versus a more random patterning of larger polygons on S. lucioceps eggs is visible under a light microscope, and will separate these eggs. Late-stage eggs are easily distinguished by the heavy pigmentation on the embryo of P. coenosus compared with the sparse pigment on Table 3, — Comparison of polygon size on chorion of eggs of Pleuronichthys and Synodun lucioceps. No ot No of Range ot eggs polygons diameters Mean SD Species measured measured (mm) (mm) (mm) Synodus lucioceps 20 200 038-0,053 0,047 0,0033 Pleuronichthys coenosus 20 200 029-0 043 035 0029 P decurrens 2 20 038-0 046 042 0021 P verticalis 2 20 037-0 051 042 0046 P ritteri 2 20 0,028-0032 0,030 0011 advanced S. lucioceps embryos, which also have a longer gut. The arrangement of polygons on the chorion of eggs of the other three species of Pleuronichthys from the eastern Pacific is similarly uniform (Fig- ure 2). The polygons are somewhat larger on the chorion of eggs of P. decurrens and P. verticalis than P. coenosus, averaging ca. 0.042 mm in both species (Table 3). Interestingly, Budd ( 1940) gave the identical value, 0.042 mm, for this measure- ment on eggs of these two species. The polygons are smaller on eggs of P. ritteri. averaging 0.030 mm. The eggs of P. cornutus were described by Mito ( 1963) and Takita and Fujita ( 1964). Mito gave the egg diameters as 1.16-1.26 mm, the oil globule as 0.016-0.020 mm. Takita and Fujita gave similar measurements for the hexagonal meshes of 0.018 mm, but gave a smaller egg diameter of 1.03-1.11 mm. Hypsopsetta guttulata Orton and Limbaugh (1953) obtained running ripe eggs of//, guttulata by stripping ripe adults and obtained similar eggs from plankton collec- tions. The eggs were notable in that they con- tained a conspicuous, moderately large oil globule. This was the first record of an oil globule in eggs of flatfishes of the family Pleuronectidae, subfamily Pleuronectinae. The egg capsule was simple, without polygonal sculpturing or other apparent texture; the yolk was homogenous. Orton (1953) gave a fairly detailed description of pigment de- velopment on embryos of//, guttulata. Neither of the above papers contained information on egg size. Eldridge (1975) reported a mean egg diame- ter of 0.80 mm with usually one oil globule of 0.14 mm in mean diameter and numerous other small oil globules in the yolk. Eggs in our samples had a mean diameter of 0.84 mm (range 0.78-0.89 mm) with a single oil globule averaging 0.13 mm in 108 SUMIDA ET AL . EARLY DEVELOPMENT OF SEVEN FLATFISHES FiGL'RE 1. — Scanning electronmicrographs of Pleuronichthys and Synodus lucwceps eggs. A. Entire egg of P. coenosus, 40 v ; B. Single polygon from same egg showing micropyle and texture of chorion surface, 1 ,880 ^■, C. Side view of same egg showing polygons in perspective and micropyle at lower left. 420 « ; D. Face view of same egg, 480 ; E. Side view of .S. /ucioceps egg showing polygons in perspective, 455 ^ ; note delicate nature of polygons; F. Face view of same egg showing irregular nature of polygons and smooth surface of chorion, 490 . 109 FISHERY BULLETIN VOL 77. NO 1 9 ^^sSSi Figure 2. — Scanning electromicrographs of P/ewronfc/j^A_vs eggs. A. Side view of P. decurrens egg. 475 x; B. Face view of same egg, 475x; C. Side viewofP. wrtica/is egg. 410 X; D. Face view ofsame egg. 450 x; E. Side view of P. n«m egg. 460 x; F.Faceviewof same egg, 475 x. 110 SUMIDA ET AL.: EARLY DEVELOPMENT OF SEVEN FLATFISHES diameter (Table 2). There was no evidence of other small oil globules in the yolk, although a few eggs had a damaged oil globule which had separated in two. However, the original oil globule could easily be determined because of surrounding pigment. The oil globule is positioned near the center of the developing embryo in middle-stage eggs. The body of the late-stage embryo is heavily pigmented, similar to the newly hatched larvae. Hippoglossina stomata Eggs of H. stomata have not been previously described. Eggs are round with a slightly pinkish, unornamented shell and a single oil globule. The egg has a mean diameter of 1.29 mm (range 1.22- 1.38 mm) and the oil globule a mean diameter of 0.23 mm (range 0.20-0.26 mm) (Table 2). The oil globule lacks pigment and lies near the tip of the tail of developing embryos in middle-stage eggs. In late-stage eggs the oil globule is in the posterior part of the yolk sac; the embryo is heavily pig- mented over the body except for the posteriormost portion of the tail; pigment patches occur on the finfolds in the same places as in early preflexion stage larvae; pigment is widespread over the yolk surface. DESCRIPTION OF DEVELOPMENTAL STAGES— LARVAL, TRANSFORMING, AND EARLY JUVENILE Pleuronichthys decurreiis Jordan and Gilbert (curlfin turbot) Figures 3, 4 Literature. — A series of egg stages and two preflex- ion larvae of P. decurrens were described and il- lustrated by Budd ( 1940) but incorrectly identified as P. coenosus. His larval illustrations,were based on a recently hatched specimen, 5.54 mm, and an emaciated specimen. 8 days old, of somewhat smaller size. Distinguishing characters. — Larvae of this species are unique in the genus Pleuronichthys in de- veloping a pterotic spine on each side of the head, in having a higher precaudal vertebral number of 14 or 15, and in having the largest larvae during all stages of development. Larval pigmentation is heaviest in this species with the body and finfold entirely pigmented except for the posteriormost region. Because of their relatively large size and dense pigment, P. decurrens larvae cannot be con- fused with Hippoglossina stomata or Hypsopsetta guttulata. Pigmentation. — Newly hatched, preflexion, and early flexion larvae (4.9-9.8 mm NL) are heavily pigmented over the head, trunk, tail, and finfolds with only the pectoral fin and posteriormost tip of the notochord and finfold unpigmented (Figure 3 A, B, C). As the first few caudal rays become evident (ca. 9.7 mm NL), several small, discrete melanophores appear on the pectoral fin base (Figure 3Ci. In late flexion and early postflexion stages during dorsal and anal fin development, the continuous heavy pigment on the finfolds changes to form three to four dorsal and three ventral bands of pigment which extend out from the body margin to part of the rayed fin membrane (Figure 3D). Larvae at this stage have a soft, saccular body with semitransparent and sparsely pigmented areas in the pterygiophore region between the body proper and developing dorsal and anal fins. Larvae >11.2 mm SL have dorsal and anal pterygiophores fully developed; the pterygiophore region is no longer transparent and the specimens become robust (Figure 4). Morphology. — Larvae of P. decurrens are the largest members of the genus at hatching and attain the largest size before transformation. Our smallest specimen is 4.9 mm NL and has yolk remnants (Table 4). The left eye begins to migrate at 10.5 mm SL and has not completed migration in a larva 21.0 mm SL. The smallest available juvenile is 29.4 mm SL. The gut begins as a tube which diminishes in diameter posteriorly and ends with a free terminal section that diverges from the body in a slight posteriad direction. In 5- to 7-mm NL larvae, the gut increases markedly in diameter and the free terminal section becomes vertical to the body axis. At about 8.0 mm NL, the gut begins to coil and its terminal section begins to slant anteriad. Coiling and the anterior displacement of the anus become more marked as development proceeds. This is reflected in the decreasing relative snout-anus length in postflexion larvae and especially in juveniles (Table 5). Relative head length increases during larval development whereas relative snout length de- creases (Table 5). Relative eye width decreases slightly during the three phases of the larval 111 112 SUMIDA ET AL., EARLY DEVELOPMENT OF SEVEN FLATFISHES Figure 3. — Larval stages of Pleuronichthys decurrens: A. 5.9 mm; B. 6.5 mm; C, 9 7 mm; D 10.0 mm. Figure 4. — Transforming specimen of Pleuronichthys decurrens. 14 A mm. T.ABLE 4. — Morphometries, in millimeters, of larvae and a juvenile o( Pleuronichthys decurrens. (Specimens between dashed lines are undergoing notochord flexion.) Snout Body Body Caudal Caudal Snout Body Lett Noto- to Head Snout Eye Eye depth at depth peduncle peduncle to origin Station length eyei chord^ anus length length width height P baseJ at anus^ depth length pelvic fin 5401-90 60 4 9NL Sym Str 24 80 14 30 024 0,54 0,64 — — — 5704-87 50 56 Sym Str 30 1 1 20 40 32 090 96 — — — 6501-63 52 60 Sym Str 30 1 1 20 40 36 090 74 — — — 5206-70 65 65 Sym Str 32 1 2 22 42 40 94 1 1 — — — 6501-60 70 79 Sym Sir 39 1 6 30 50 48 1 3 1 3 — — — 5003-87 35 85 Sym Str 4 1 18 32 60 56 1 7 1 8- — — — 6606-60 65 93 Sym Str 43 20 32 66 62 1 6 18- — — — 6605-80 80 98 Sym Str 43 2 2 36 68 064 20 2 2- — — — 5706-93 65 78 Sym E II 39 1 9 30 064 064 2 3- 23- _ _ 5711-87 55 9 1 Sym Ell 4 7 2 1 40 70 66 2 4- 25- — — — 5401-85 60 100 Sym Midll 44 26 44 80 72 2.8- 3 0- — — 27 6507-87 55 110 Sym L fl 58 32 48 98 1 40- 4 6- — — 33 5009-47 60 102 SL Sym Flexed 53 34 60 96 94 4 5- 4 6- 1 060 34 5407-60 70 105 Migr Flexed 55 36 064 1 1 1 1 4 9- 5 4- 1 64 34 5805-70 80 11 2 Migc Flexed 57 39 64 1 3 1 2 5 2- 59- 1 3 68 36 7505-90 70 14 5 Migr Flexed 62 52 66 1 6 96 8 1- 86- 2 1 83 46 4903-82 57 154 luligr Flexed 70 5 7 67 1 8 1 7 9 0- 9 7- 2 1 1 1 4 7 6609-80 60 170 Migr Flexed 87 64 67 1 9 1 5 9 2- 11 4- 29 1 2 60 5308-73 60 192 f^4igr Flexed 7 7 65 091 1 7 1 5 10 0- 11 4- 28 1 2 64 5004-97 32 21 Migr Flexed 84 67 66 1 7 1 7 11 7- 124- 32 1 4 62 OtI Santa Cruz Island, Calif 29 4 Over Juv 97 90 66 33 25 139- 14 5- 36 22 68 'Sym - symmetrical. Migr migrating. ^Str - straight, E fl - early fleKion. Midll - midllexion, L fl late flexion. Juv - juvenile ^Asterisk indicates inclusion of dorsal fin pterygiopfiores in body depth measurement. 113 FISHERY BULLETIN: VOL 77, NO 1 fa ? s a tfi (D O _ g> a "5 a X S^ Q. OJ o i. c K O ifi t -c °- J S iJ 1 Q -2 ^ J: s g X 3 1 3 M a 1 ^ h L. a> e- a o » e l-s 1 t « « > ^ d. u nj "D — : ? i ^ g :S 2 Si cn ffl (J tft o 11 a; 1= > ?■§ <1> > T3 0* fc. « ffl '^ '5 =■ S « 2 3 C C a> cB o > QJ . *J -o U o O J2 S-o C O. 0) Q •&2 1 5 c o '^ S s. 1 ^ IT) ^ 1 U -3 CQ < H in •- Tt U5 ^ ^ ^ (O CO CO c^ a> 'J •- CM CM ■^ W in in to CD ^ If) CM CM '^CO'^CO CMCMCOCO "-CMCM*- COCOCOCO CMCOCM (D •- O T- in CO ^ O O CM CO n ^ CO CM CM CM CM 1 CD CO r- CM ■* o o ' - CMO +1 (1 CD O O tl +1 CD in H 41 in in 'i: tl jl ^ o in CD CD CO CM CM n fO CO CJ) CD CD ■* 00 CD CM CM CM CM Q CM CD in in m CO in r- CO ^ CM CM CO (O tD O O h- CM CM CM -■ in CO (O (D •^ CO CO CO h- O CO o CO CO CM CO in ■^ CM CM CM CO CM CM . 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The head is relatively larger in preflexion lar- vae of P. ritteri than in the other species (Table 5). Relative head length increases throughout the larval period, then is moderately reduced at trans- formation. Mean relative snout length increases in P. ritteri larvae undergoing notochord flexion and decreases during subsequent .stages, but in other species ofPleuronichthys it decreases during all major phases of larval development. Relative eye size is largest in preflexion larvae, becomes reduced in later larval stages, and increases at transformation. The early larvae of P. ritteri are the deepest bodied species of Pleuronichthys. Mean relative body depth measured at the base of the pectoral fin is greater during preflexion and flexion stages of the notochord than in any other species. In post- flexion larvae, however, mean relative body depth is markedly less than in P. decurrens and about equal to that in P. coenosu.'i and P. vertieali.s (Table 5). Fm and axial skeleton formation. — Early caudal formation involving thickening in the hypural area of the developing caudal fin occurs on larvae 4.3-5.1 mm NL (Table 15). Caudal rays are forming on larvae as small as 4.5 mm NL, with a simultaneous initiation of flexion of the notochord. Specimens between 4.5 and 5.6 mm NL undergo notochord flexion. Our smallest specimen with a fully flexed notochord is 5.3 mm SL. The full 128 SUMIDA ET AL.. EARLY DEVELOPMENT OF SEVEN FLATFISHES FlClIRE 15.— Reared larval stages oi Pleuronichthys ritleri. A 2.1 mm; B. 3.0 mm; C. 4.2 mm; D. 4.2 mm. dorsal view. 129 FISHERY BULLETIN VOL, 77, NO Figure 16— Lan-al stages of P/eumnichlhys ntleri: A. 5.6 mm; B. 5.5 mm; C. 6.4 mm. 130 SUMIDA ET AL. EARLY DEVELOPMENT OF SEVEN FLATFISHES Figure 17. — Transforming specimen o( Pleurontchthys ntteri, 10.0 mm. Table 14. — Morphometries, m millimeters, of larvae and juveniles oi Pleuronichthys ntteri. (Specimens between dashed lines are undergoing notochord flexion.) Snout Body Body Caudal Caudal Snout Body Left Noto- to Head Snout Eye Eye deptti at deptti peduncle peduncle to to origin station lengthi eye' ctiord' anus lengtti lengtti widtti fieigtit P base> at anus^ deptti lengtti pelvic fin Oft La Jolla, Calit 2 1 NL Sym Sir 1 2 50 10 024 0.20 20 38 — — — 30 Sym Str 1 4 60 12 26 22 42 42 — — — 7412-123 36 33 Sym Str 1 6 80 14 28 024 78 58 — — — Off La Jolla 42 Sym Str 22 1 18 40 32 96 86 — — — 5709-117 26 43 Sym Str 2 1 1 1 020 40 36 1 2 12- — — — 7207-123 36 4 4 Sym Sir 2 1 1 1 024 34 32 1 09 — — — 6204-120 25 50 Sym Str 22 1 2 20 38 38 1 2 1 r — — — 5708-12025 51 Sym Str 25 14 24 046 0,40 1 8- 1 7' — — 1,3 6507-120 35 45 Sym E fl 23 1 4 32 44 42 1 6- 1 6- 1 2 5506-120 40 48 Sym Ell 23 1 4 28 40 038 1 5- 1 7- — — 14 5510-11726 55 Sym Midll 2 7 1 2 34 52 48 2 0- 1 9- — — 16 7501-120 25 56 Sym Midfl 2 7 1 5 26 46 40 1 8- 1 5- — — 1 4 5112-120 35 5 3SL Sym Flexed 27 1 7 30 52 52 2 2- 2 2- 50 36 1 4 5802-137 23 60 f^igr Flexed 29 20 32 60 54 2 4- 2 7- 66 30 1 8 Oft La Jolla 64 fvligr Flexed 26 22 040 064 60 2 5- 2 7- 76 38 20 Sebastian Viscaino Bay, B C 75 A over Flexed 30 26 40 80 64 2 9- 3 0- 1 48 27 7501-120 22 4 85 A over Flexed 28 27 40 86 7 3 6- 3 6- 1 1 44 23 Off La Jolla 100 Over Flexed 31 31 48 1 80 4 2- 4 2- 1 4 60 26 Reared 127 Over Juv 42 38 36 1 4 1 5 1- 5 4- 1 4 76 34 Reared 150 Over Juv 45 42 48 1 6 1 2 5 9- 6 1- 1 8 1 39 Reared 167 Over Juv 52 4 7 48 1 8 1 4 6 2- 6 4- 20 1 1 42 Off San Juanico, B,C 23 Over Juv 72 68 0.83 22 9 9 7- 9 7- 26 1,2 58 'Sym - symmetrical, Migr - migrating A over - About over 2Str - straigtit, E fl - early flexion, fvlidtl - midflexion, Juv - juvenile ^Asterisk indicates inclusion of dorsal fin pterygiophores in body deptti measurement caudal count of 19 rays was observed on a 6.0-nim SL postflexion specimen. Dorsal and anal fin bases are forming in the finfold on larvae 4.3 mm NL, and the full comple- ment of rays develops by 6.0 mm SL. Pelvic fin buds are evident during early caudal formation but rays are first observed on a 6.0-mm specimen. Pectoral rays were fully formed on a 10.0-mm 131 FISHERY BULLETIN VOL 77. NO. 1 Table 15. — Meristics of larvae and juveniles o( Pleuronichthys ritteri. (Specimens between dashed lines are undergoing notochord flexion.) Fin rays Size Pectoral station (mm) Stage' Dorsal Anal Caudal Pelvic right/left Off La Jolla. Calif. 2 1 NL Yolk-sac LP' 30 Prell LP= 7412-123 36 33 Prell LP= Ofl La Jolla 42 Prefl LP' 5709-117.26 43 Prefl Forming Forming Forming LP' 7207-23 36 44 Prell Forming Forming Forming LP' 6204-120.25 50 Prefl Forming Forming Forming LP' 5708-120 25 5 1 Prell Forming Forming Forming Bud LP' nghl/left Precaudal Caudal Total Source of count 6507-120 35 45 E fl Forming Forming ca 6 Bud LP' 5506-120 40 48 Efl Forming Forming ca 4 Bud LP' 5510-117 26 55 lulidfl Forming Forming ca 8 Bud LP' 7501-120 25 56 Midfl Forming Forming ca 8 Bud LP' 5112-120 35 5 3SL Postfl ca 60 ca 45 16 Bud LP' 5802-137 23 60 Postfl 72 49 19 6;6 LP' Oil La Jolla 64 Postfl 65 45 19 6/6 LP' Sebastian Visca no Bay, B C 75 Postfl 70 48 19 6/6 LP' 7501-120 22 4 85 Postfl 69 51 19 6/6 LP' Off La Jolla 100 Postfl 68 47 19 6/6 9/9 12 23 35 X-ray Reared 12 7 Juv 69 47 19 6/6 10/11 12 23 35 X-ray Reared 150 Juv 64 44 19 6/6 10/11 12 23 35 X-ray Reared 16 7 Juv 65 44 19 6/6 11/11 12 22 34 X-ray Off San Juanico BC 23 Juv 68 49 Damaged 6/6 9/9 12 23 35 X-ray 'Prefl - preflexion, E fl - early flexion, fwlidfl - midflexion, Postfl - postflexion; Juv - juvenile 'LP refers to functional larval pectoral fins wfiicti tiave no ossified rays larva. A radiograph of this specimen showed 12 precaudal and 23 caudal vertebrae, the typical count for this species. Distribution. — This species ranges from Morro Bay. Calif., to Magdalena Bay, Baja California (Fitch 1963; Miller and Lea 1972; Fierstine et al. 1973). Our egg and larval material, which was collected between .southern California and Mag- dalena Bay, Baja California, shows a markedly coastal, inshore distribution for P. ritteri, with a majority of collections made over or near the con- tinental shelf (Figure 18). Hypsopsettii giittnlata Girard (diamond turbot) Figures 19-22 Literature. — Orton and Limbaugh (1953) and Orton (1953) briefly described the eggs of//, gut- tiilala. Eldridge (1975) described and illustrated larvae of this species, and noted the average size of its egg and oil globule. Although the larval series is quite well described in Eldridge (1975) (except for the omission of the pterotic spine on the head), we are including information about distinguish- ing characters, pigmentation, etc. to facilitate identification. Distinguishing characters. — Larvae of H. gut- tulata are distinguishable from species of Pleuronichthys, except for P. ritteri, by their lower total vertebral number, by attaining comparable stages of development at smaller sizes, and by the presence of a pterotic spine on each side of the head in yolk-sac larvae to midflexion larvae. In the genus Pleuronichthys, only P. decurrens develops pterotic spines. (See Distinguishing characters for P. decurrens. ) The only species with which larval H. guttulata may be confused is P. ritteri because of its rela- tively small size and somewhat similar pigment pattern. (See Distinguishing characters for separating larvae of the two species discussed under P. ritteri .) Pigmentation. — Yolk-sac larvae are heavily pig- mented on the head, trunk, and for a short dis- tance on the tail, with the posteriormost 9 or 10 myomeres remaining unpigmented (Figure 19A). Pigment spots are scattered over the ventral and posterior surfaces of the yolk sac and oil globule, and over the terminus of the gut. Preflexion larvae show little change in pigment pattern. One or two melanophores develop on the pectoral fin base. The isthmus has a line of pig- ment spots, and the entire abdominal area is cov- ered with pigment (Figure 19B.). 132 SUMIDA ET AL- EARLY DEVELOPMENT OF SEVEN FLATFISHES 129° 125° 121° 40' 35' 30' 25' 20° /^ T- 1- -r -r / /^ V T" MENDOCINO MAGDflLENA _ 40° 35° 30° 25° 115° 110° 106° Figure 18. — Distribution of eggs and larvae of Pleuronichthys ritteri examined in this study. (Triangles represent eggs, open circles larvae, and closed circles eggs and larvae. t At the initiation of dorsal and anal fin forma- tion, the tail pigment spreads out dorsally and ventrally onto the finfold, resulting in conspicuous dark mounds of pigment opposing each other in the area between the body and the dorsal and anal fin bases (Figure 19C). The tops of the head, nape, and shoulder area are pigmented in contrast to P. ritteri. which has an unpigmented streak dorsally (Figure 19D). Flexion, postflexion, and early transforming specimens maintain the earlier pigment pattern and the only obvious change is a slight posteriad extension of trunk pigment, leav- ing 5 or 6 unpigmented myomeres posteriorly compared with 9 or 10 in earlier stages (Figure 20). The base of the pectoral fin acquires more pigment spots in postflexion larvae, and pigment on the head similarly increases in density (Figure 20B). Preserved small juveniles are brownish-black with numerous small, dark spots scattered over the body and pterygiophores, giving them a mot- tled appearance (Figure 21). Morphology. — Our smallest yolk-sac larva is 2.2 mm NL and has a posteriorly positioned oil globule 0.14 mm in diameter (Figure 19A). The left eye is beginning to migrate in a specimen 4.4 mm SL and is complete in a 7.3-mm SL larva (Table 16). The smallest available juvenile was 11.2 mm SL. A major distinguishing feature of Hypf^opxetta larvae is the presence of a pterotic spine on each side of the head. The spines are present on the smallest yolk-sac larva and are prominent in most preflexion larvae. The spines begin to regress on late preflexion larvae, and are totally regressed in late flexion specimens. In P. deciirrens the spines are well developed throughout the larval period and begin to regress late in the postflexion stage. Although mean relative body depth of H. gut- tiilata larvae increases with development, it is slightly less in postflexion specimens than in any species of Pleuronichthys , except P. ocellatiis (Ta- ble 5). In newly transformed juveniles, however, relative body depth is greater than in any species oi Pleuronichthys. As a juvenile. H. guttulata as- sumes a diamond-shaped body form. Relative body width is useful to separate Hyp- sopsetta larvae from those of P. ritteri. As shown in Figures 15D and 19D, larvae of Hypsopsetta have narrower bodies. Fin formation. — The caudal fin forms on larvae between 4.0 and 5.2 mm NL and is complete on some specimens as small as 4.4 mm (Table 17). The dorsal and anal fins form simultaneously with the 133 FISHERY BULLETIN VOL 77. NO 1 FIGURE 19.— Larva] stages o[ Hypxopseltu guttulata: A. 2.2 mm; B. 2.6 mm; C. 4.6 mm; D. 4.6 mm, dorsal view. 134 SUMIDA ET AL : EARLY DEVELOPMENT OF SEVEN FLATFISHES Figure 20.— Larval stages of Hypsopsetta guttulala: A. 5.9 mm; B. 6.6 mm. caudal and are complete, or nearly so, on all post- flexion specimens (4.4-8.8 mm SL). Pelvic fins are late in forming compared with their developmen- tal pattern in Pieiironichlhyn larvae. Pelvic buds can be observed only after notochord flexion has been completed, and rays are first evident on the 6.6-mm SL specimen. Distribution. — Hypsopsetta guttulata ranges from Cape Mendocino. Calif., to Magdalena Bay, Baja California, with an isolated population in the upper Gulf of California (Norman 1934; Fitch 1963). Egg and larval material examined by us was collected in bays along the coast, or at Cal- COFI stations located over the continental shelf, a pattern of distribution similar to the habitat of P. ritteri (Figure 22). Hippoglossitia stoma ta Eigentnann and Eigenmann (bigmouth sdIc) Figure 23 Literature. — There is no published account of eggs and larvae of this species. However, Leonard ( 197 1 ) described a larval series oiH. oblonga from the western North Atlantic. Earlier, Agassiz and Whitman ( 1885) and Miller and Marak 1 1962) de- scribed the eggs and early-stage larvae of//, ob- longa. Miller and Marak reported the egg size range as 0.91-1.12 mm (average 1.04 mm) with an oil globule diameter ofca. 0.1 7 mm. The larval size at hatching was 2.7-3.2 mm. Distinguishing characters. — Preflexion larvae of H. stomata may be confused with early larvae of P. 135 FISHERY BULLETIN: VOL. 77. NO 1 m^iCfei,. ^^^-:^^ij,n •%.?.:U^<^---^^ •■-.5 '•^^«;i^ ^: .^^ ..*, Figure 21, — Early juvenile o{ Hypsopsetta guttulata. 1.3.2 mm. coenosus and P. uerticalts due to similarities in size and pigmentation of the larvae, and the pres- ence of pigment on the finfold dorsally and ven- trally, posterior to the anus. Characters of H. stomata larvae which distinguish them from preflexionP. coenosus larvae include the presence of a pigment bar through the eye, heavy pigment on both sides of the pectoral fin base and a sprinkl- ing of pigment on the pectoral blade, a more slen- der, elongate body, and a significantly smaller patch of dorsal finfold pigment. The same charac- ters help to distinguish H. storjiata from P. ver- ticalis. except for the finfold pigmentation. Pleuronichthys verticalis has small, triangular- shaped pigment patches whereas H. stomata has a small rounded pigment cluster on the dorsal finfold and a broad patch on the ventral finfold. Larvae of P. verticalis are also smaller than H. stomata at similar developmental stages. Larvae in the flexion stage and larger are read- ily separable from Pleuronichthys by the preoper- cular spines and development of several elongated dorsal rays in the anteriormost part of the dorsal fin. These do not develop on larval Pleuronichthys or Hypsopsetta. L36 Pigmentation. — Yolk-sac larvae (ca. 3.7 mmi are heavily pigmented on the trunk and tail except for the posteriormost part of the tail which is pig- mented with several small spots dorsally and ven- trally (Figure 23A). The upper head and abdomi- nal region have scattered pigment, with a more concentrated bar of pigment on each side of the eye. Both sides of the pectoral fin base are con- spicuously pigmented. Finfold pigment consists of a small, rounded patch at the edge of the dorsal finfold, and a broad patch on the ventral finfold, both situated posterior to the anus near the mid- point between the anus and tip of the tail (Figure 23Ai. Preflexion larvae, 4. 1-7.0 mm NL, undergo little change in pigmentation except to augment pig- ment in areas of the pectoral fin, abdominal re- gion, and top of the head (Figure 23Bi. On larvae forming the dorsal and anal fins, the dorsal finfold pigment spreads to include the area between the fin rudiments and body margin, and the ventral finfold pigment spreads both an- teriorly and posteriorly (Figure 23C). Pigment on the pectoral fin base intensifies and also extends out onto the fin blade. SUMIDA ET AL.; EARLY DEVELOPMENT OF SEVEN FLATFISHES Table 16. — Morphometries, in millimeters, of larvae and juveniles of Hypsopselta guttulata. (Specimens between dashed lines are undergoing notochord flexion. I Snout Body Body Caudal Caudal Snout Body Letl Noto- to Head Snout Eye Eye depth at depth peduncle peduncle to ongin Station length eye' chord' anus length length width height P base^ at anus^ depth length pelvic fin San Diego Bay 2 2 NL Sym Sir 1 1 38 08 17 13 18 28 _ King Harbor, Calif 23 Sym Sir 1 1 46 12 20 017 18 34 _ 7501-120 25 28 Sym Sir 1 4 068 012 26 22 62 052 _ _ 7501-120 29 33 Sym Sir 1 7 82 20 30 24 82 72 _ San Diego Bay 36 Sym Sit 1 8 084 16 32 28 78 066 _ _ _ San Diego Bay 40 Sym Sir 20 88 20 36 030 88 084 _ 7412-127 32 6 4 4 Sym Sic 22 90 20 037 32 1 092 - - - 7412-127 32 6 46 Sym Ell 23 1 2 24 38 32 1 1 1 7501-120.224 49 Sym Efl 24 1 3 22 40 36 1 2 1 1 — _ _ 7501-120.29 51 Sym E fl 25 1 2 22 0,40 036 11 1 1 _ _ King Harbor 52 Sym Lfl 24 1 4 28 44 0.42 12 12 — - - L A Harbor Calif 4 4 SL Migr Flexed 22 1 6 30 48 42 1 8- 1 9- 40 40 1 4 La Jolla. Calif 48 Migr Flexed 22 1 5 30 48 40 1 6- 1 T 40 36 1 4 San Diego Bay 54 Migr Flexed 23 18 34 52 40 1 8- 1 9- 42 42 1 6 7501-120,22.7 59 Sym Flexed 31 1 8 32 50 046 2 0- 2 2- 44 48 1 9 7501-120,24 66 Migf Flexed 32 2 1 40 62 052 2 3- 2 4- 50 60 20 Reared 73 Over Flexed 29 25 40 090 70 3 3- 3 5- 76 064 2 1 Reared 79 Over Flexed 29 27 44 92 68 3 6- 3 8- 86 70 2 1 Reared 8,8 Over Flexed 36 30 48 1 076 4 1- 4 2- 096 068 26 Reared 112 Over Juv 4 2 37 50 1 4 1 1 5 7- 6 0- 1 4 1 33 Richardson Bay 129 Over Juv 45 43 52 1 2 92 7 0- 7 0- 1 5 10 36 Calif 132 Over Juv 48 43 75 1 3 1 1 6 7- 7 r 1 4 1 36 140 Over Juv 50 47 75 1 4 1 2 7 5- 77- 1 6 1 2 38 145 Over Juv 52 48 72 1 4 1 7 7- 7 9- 1 8 88 4 1 184 Over Juv 64 58 80 1 7 1 4 10 0- 10 5- 2 1 1 4 5 1 'Sym symmetrical, Migr - migrating ^Str - straight; E (I - early flexion, L Tl - late flexion. Juv )uvenile ^Asterisk indicates inclusion of dorsal tin pterygioptiores m body depth measurement Table 17. — Menstics of larvae and juveniles of Hypsopsetta guttulata. (Specimens between dashed lines are undergoing notochord flexion.) Size Fin rays Verlebrap Pectoral station (mm) Stage' Dorsal Anal Caudal Pelvic right/left Precaudal Caudal Total of count 7501-120 25 2 8 NL Prefl LP' 7501-120 29 33 Prefl LP' San Diego Bay 3.6 Prefl LP' San Dieqo Bay 40 Prefl Forming Forming Forming LP' 7412-127 32 6 4 4 Prefl Forming Forming 6 LP' 7412-127 32 6 45 Efl Forming Forming 8 LP' 7501-120 22 4 49 Ell Forming Forming 6 LP' 7501-120 29 51 E II Forming Forming 4 LP' King Harbor, Calif 52 L fl ca 50 ca 35 15 LP' LA Harbor, Calif 4 4 SL Postfl 67 47 19 Bud LP' Off La Jolla, Calif 48 Postfl 66 49 19 Bud LP' San Diego Bay 54 PosHI 73 45 19 Bud LP' 7501-120 22 7 5.9 Postfl 73 46 19 Bud LP' 7501-120 24 66 PosHI 69 50 19 6 6 LP' Reared 7 3 Postfl . 68 47 19 6,6 11 11 1 1 23 34 X-ray Reared 79 Postfl 67 51 20 6,6 12 12 12 23 35 X-ray Reared 88 Postfl 72 50 19 6;6 13/13 12 23 35 X-ray Reared 112 Juv 73 48 19 4/6 12/12 12 22 34 X-ray Richardson Bay, Calif 129 Juv 66 48 19 5/6 12/11 12 23 35 X-ray 132 Juv 74 53 19 6/6 11/11 12 23 35 X-ray 140 Juv 78 55 19 6/6 11/11 12 23 35 X-ray 14 5 Juv 71 51 19 6/6 12/12 12 23 35 X-ray 184 Juv 68 51 19 6/6 11/12 12 23 35 X-ray 'Prefl - preflexion, E fl - early flexion, L fl - late flexion, Postfl - postflexion, Juv 'LP refers to functional larval pectoral fins which have no ossified rays juvenile Postflexion and early transforming specimens are less heavily pigmented than earlier stage lar- vae, with a noticeable diminution of pigment on the dorsal area of the head and body ( Figure 23D ) . Morphology. — Larvae of H. stomata are closest to P. coenosus in size at hatching, notochord flexion, and transformation (Table 18). A specimen 3.7 mm NL has a moderate amount of yolk remaining. 137 FISHERY BULLETIN: VOL. 77. NO 1 129° 125° 121° 40' 35< 30' 25' 20' 40° MAGDALENA 115° Figure 22. — Distribution of eggs and larvae of Hypsopsetta gut- tulata examined in this study. (Open circles represent larvae, closed circles eggs and larvae.) The right eye is beginning to migrate in a speci- men 9.1 mm SL and transformation is almost complete at 11.7 mm SL. In early preflexion larvae of Hippoglossina, the gut is shaped like that in Pleuronichthys larvae; however, coiling begins at about 4.5 mm NL and the gut assumes a more compact shape than in Pleuronichthys. This is reflected in the relatively shorter snout-anus length. Mean relative snout- anus length remains at about 4CK7c of the body length throughout the larval period, in contrast to Pleuronichthys larvae in which there is a gradual decrease in relative gut length during larval de- velopment (Table 5). In juveniles, however, there is a decrease in snout-anus length to about 33% of body length, a value comparable with that in Pleuronichthys juveniles. The head is similar in size and shape to that in Pleuronichthys. Relative head length increases gradually during larval development. The same is true for relative snout length and is thus opposite to the condition in Pleuronichthys; however, it de- creases somewhat in juveniles. Relative eye width undergoes a moderate diminution during larval development as in Pleuronichthys, but increases moderately in juveniles. Small preopercular spines develop on larvae from ca. 5.5 mm NL, become most conspicuous on flexion stage larvae, and undergo resorption dur- ing transformation from 9.5 mm SL. This spina- tion is distinctive of H. stomata when compared with Pleuronichthys and Hypsopsetta. Larvae oi Hippoglossina have a slender appear- ance compared with .some of the deeper bodied species of Pleuronichthys. Body depth at the anus is comparatively small in preflexion larvae and remains so in flexion and postflexion larvae and early juveniles (Table 5). As in Hypsop.'ietta, the caudal peduncle is longer and more slender than in Pleuronichthys, except for P. ocellatus postflexion larvae. Fin formation. — Larvae of Hippoglossina stomata are comparable with those of P. coenosus with regard to size at which the caudal fin develops. Caudal fin formation occurs between 6.2 and 8.8 mm NL (Table 19). Although about six caudal rays are formed on a 7.0-mm NL specimen with a straight notochord, all other specimens with caudal rays have the notochord flexing. The smallest, fully flexed specimen is 7.1 mm SL. Postflexion specimens <9.0 mm SL lack the full complement of I8V2 caudal rays. The ural bones supporting the caudal rays are made up of two superior and two inferior hypurals; there is no epural. The lack of an epural bone is a specific 138 SUMIDA ET AL.i EARLY DEVELOPMENT OF SEVEN FLATFISHES Figure 23.— Larval stages of Hippog/ossma slomala: A. 3.8 mm; B. 4.8 mm; C. 8.3 mm; D. 8.6 mm. 139 FISHERY BULLETIN: VOL. 77, NO 1 Table 18. — Morphometries, in millimeters, of larvae o( Hippoglossina stomata. (Specimens between dashed lines are undergoing notochord flexion.) Snout Body Body Caudal Caudal Snout Body Lett Noto- to Head Snout Eye Eye depth at depth peduncle peduncle to origin Stalion length eye' chofd' anus length length width height P base^ at anus^ depth length pelvic tin 720M1735 3 7NL Sym Sir 1 4 0,64 0,10 28 0,21 50 40 _ _ _ 7412-103 29 4 1 Sym Sir 1 8 0,72 007 24 24 48 36 — — — 7412.88,5.31 4.8 Sym Sir 2 10 24 36 028 0% 068 — — — 5801-117 35 5.2 Sym Sir 22 1 2 24 48 36 1 2 082 — — — 6310-93 28 6.2 Sym Str 22 1 3 026 42 036 12 0,92 — — — 6605-123 37 64 Sym Str 22 1 3 24 44 36 1 4' 1 — — — 5910-117 30 6.2 Sym Str 28 1 6 30 054 42 2 1- 1 3 — — — 6706-110 50 70 Sym Sir 28 1 8 32 50 42 21- 1 8- — — — 5708-118 5 35 66 Sym Ell 27 1 7 40 054 54 21- 1 7- 1.5 5706-127 34 75 Sym Ell 30 20 36 66 70 22- 18- — — 1 8 6912-83 60 83 Sym E (1 32 1 8 42 60 66 24- 20- — — 20 5807-130.30 7.6 Sym Midll 29 1 9 38 064 058 2 2- 2 0- — — 1 8 5709-110 30 79 Sym Midfl 29 19 42 60 052 2 2- 2 0- — _ 17 6706-12337 88 Sym Midtl 34 23 44 68 060 28- 24- — — 24 5706-12337 76 Sym L (1 3 1 2 1 46 66 64 2 5- 2 3- — — 18 6706-123 36 85 Sym L II 34 23 44 70 66 2 8- 2 6- — — 23 6608-120 30 7 1 SL Sym Flexed 3 1 22 46 76 78 2 6- 2 4- 66 062 21 5708-115 35 80 Sym Flexed 33 24 064 72 68 29- 27- 062 070 20 6706-123 37 90 Sym Flexed 39 27 52 84 84 3 4- 3 0- 070 82 27 6410-83 43 94 Sym Flexed 37 27 56 84 84 3 6- 3 8- 80 84 23 5701-120 35 9 1 Migr Flexed 38 3 1 72 1 96 3 7- 4 r 092 68 27 5709-110 33 99 Migr Flexed 40 32 80 90 086 4 1' 43- 0.90 76 26 6706-123 36 105 Migr Flexed 4 1 35 80 1 1 94 3 8- 3 9' 98 88 30 5507-130,30 11 7 Migr Flexed 42 37 096 10 088 44- 4 5- 12 0.90 35 Asuncion Bay. 358 Over Juv 124 12,2 23 4,3 — 134- 130- 3.2 2.9 10.5 BC 38 2 Over Juv 122 13,5 27 42 — 14,2- 13.7- 3.8 3.4 11.4 'Sym - symmetrical. Migr - migrating ^Str straight, E tl - early llexion, Midll - midflexion, L tl - late flexion, Juv - luvemle. ^Asterisk indicates inclusion ol dorsal tin pterygiophores in body depth measurement. Table 19. — Menstics of larvae and juveniles oi Hippoglossina stomata. (Specimens between dashed lines are undergoing notochord flexion.) Size Fin rays Vertebrae Pectoral Source Station (mm) Stage' Dorsal Anal Caudal Pelvic righflell Precaudal Caudal Total ol count 7201-117 35 3 7 NL Prell LP^ 7412-103 29 4 1 Prell LP2 7412-88531 4.8 Prell LP^ 5801-11735 5.2 Pretl LP' 6310-93 28 6.2 Pretl LP' 6605-123 37 6.4 Prell Anterior swelling LP' 5910-117 30 6 2 Prell Forming Forming LP' 6706-110 50 70 Prell Forming Forming ca 6 LP' 5708-118 5 35 66 Ell. Forming Forming ca 6 Bud LP' 5706-127 34 75 Efl Forming Forming ca 10 Bud LP' 6912-83 60 83 Ell Ant 4 Forming ca 10 Bud LP' 5807-130 30 7.6 lyiidll ca 15 ca 15 12 Bud LP' 5709-110 30 7.9 Midfl ca 55 ca 45 12 Bud LP' 6706-123 37 8.8 Midtl ca, 62 ca 50 16 Bud LP' 5706-123 36 7.6 Lfl ca 63 ca 45 14 Bud LP' 6706-123 36 8.5 Lll ca, 68 ca 50 14 Bud LP' 6608-120 30 7 1 SL Postll ca 66 ca 51 16 ca, 5/5 LP' 5708-115 35 8.0 Postll 63 50 ca 18 6/6 LP' 6706-123 37 9.0 Postll 68 53 18'i 5,' 5 LP' 6410-83 43 9.4 Postll 68 54 ca 18 6/6 LP' 5701-120 35 9.1 Postll 67 53 18''i 66 LP' 5709-110 33 9.9 Postll 65 50 18',i 6/6 LP' 6706-123 36 10.5 Postll 66 53 18'/i 6/6 LP' 5507-130 30 11.7 Postll 64 50 18'/! 6/6 LP' Asuncion Bay. 35.8 Juv 67 52 18"j 6/6 10,'10 11 27 38 x-ray BC 38 2 Juv 65 50 1 7','i 6/6 10/10 11 27 38 X-ray 'Prell - prellexion. E fl - early flexion Midll - midllexion, L 11 - lale llexion : Postfl, - postllexion Juv - juvenile ^LP refers to functional larval pectoral fins which have no ossified rays. 140 SUMIDA ET AL EARLY DEVELOPMENT OF SEVEN FLATFISHES character in H. stomata because other species of Hippoglossina possess this bone. The dorsal fin of//, stomata develops quite dif- ferently than in Pleuronichthys. An anterior group of about five dorsal rays is the first to form in H. stomata; these become more elongated than the other rays. The anlage of these is evident on a 6.4-mm NL preflexion specimen and four rays are formed on a 9.3-mm NL early flexion larva. A similar pattern of early forming dorsal fin rays is found in the closely related genera Paralichthys (Okiyama 1967; Smith and Fahay 1970; Ahlstrom and Moser 1975) and Pseudorhombus (Devi 1969). Although the anterior dorsal rays form early, the pelvic fins do not develop elongated rays, such as in the bothid genera Syacium (Aboussouan 1968) and Cyclopsetta (Gutherz 1970). The dorsal fin rays differentiate posteriad but most rays form simultaneously and the full complement is de- veloped on a late flexion specimen. The base of the anal fin is evident during early caudal formation, rays are forming on midflexion specimens, and the total number is formed on a late flexion specimen. Pelvic fin buds are evident on early flexion speci- mens, but rays can be distinguished only on post- flexion larvae. Distribution. — This species ranges from Monterey Bay, Calif., to the Gulf of California, including Guadalupe Island (Miller and Lea 1972). Larvae occurred over a wide band of inshore and offshore stations (Figure 24). The southern limit of H. stomata overlaps the northern range of H. tet- rophthalmus which has different fin counts (Ginsburg 1952). To date, larvae of H. tet- rophthalmus are not known. SUMMARY We used a combination of larval morphology, meristics, and pigmentation to distinguish seven known eastern North Pacific species of flatfishes with heavily pigmented larvae. Table 20 sum- marizes many pertinent characters for identifying eggs and larvae of these species. Information is given for three characters of eggs; size, ornamen- tation of the chorion, and presence or absence of an oil globule. In most instances, the size of a newly hatched larva is directly related to the size of the egg from which it hatched, and such is the case with Pleuronichthys. Pleuronichthys decurrens. with the largest egg, has the largest larva, with a suc- 40' 35' 30' 25' 20' 129° "7 125° "7 — r CAPE MENDOCINO ^MONTEREY BAY POINT 'CONCEPTION O rJ SAN DIEGO \ O c* \, ; A J£] \i. O O o Y^ POJNT \ EUGENIA O Ox o oof '^ A } GULF \ o o y .CALIFORNIA •A MAGDALENA.-^'^^ . ( BAT \ ; . ^ 440 40° 35° 30° 25° 115° )06° FiGL'RE 24. — Distribution of eggs and larvae o^ Hippoglossina stomata examined in this study. (Triangles represent eggs, open circles larvae, and closed circles eggs and larvae.) cessive decrease in larval size of the other species corresponding to their smaller sized eggs. This also applies to the yolk-sac larvae of Hypsopsetta guttulata and Hippoglossina stomata. Pleuron- 141 FISHERY BULLETIN VOL 77. NO 1 ichthys decurrens. with the largest yolk-sac larva, is correspondingly large at caudal fin formation (notochord flexion) and at transformation, whereas Hypsopsctta guttiilata. with the smallest egg, is correspondingly smallest at all stages of larval development with the exception of some overlap with larvae of P. ritten. A larval character that is particularly useful in separating preflexion larvae of H. guttulata from those of P. ritten is the presence of a pterotic spine on each side of the head of//, guttulata. The only species of Pleuronichthys with a pterotic spine is P. decurrens. For relating a lai'val series to its juveniles and adults, and thus substantiating identification of the series, meristic counts, particularly of the pre- caudal and caudal groups of vertebrae, are indis- pensible. One can seldom rely on one meristic character alone, but must use a combination of all available counts. The distribution of pigment, which changes with growth, provides good characters for dis- criminating among larvae of the several species. It is particularly useful with preflexion larvae, and for this reason we emphasize pigment for this stage in Table 20. ACKNOWLEDGMENTS We would like to thank the following individu- als for loan of specimens: Gerald McGowen (Occi- dental College), Joseph Copp and Richard Rosenblatt (Scripps Institution of Oceanography), Maxwell Eldridge (National Marine Fisheries Service, Tiburon), Wayne White (California State University, Fullerton), Robert Behrstock (Hum- boldt State University), and Sally Richardson (Oregon State University). We are grateful to Den- nis Gruber (Scripps Institution of Oceanography) and John Butler (National Marine Fisheries Ser- vice, La Jollai for providing reared specimens. .Ap- preciation is also extended to Susan D'Vincent, Elaine Sandknop, and Betsy Stevens (National Marine Fisheries Service. La Jolla) for their assis- tance in gathering material from our collections. Henry Orr ( National Marine Fisheries Service, La Jolla) deserves thanks for some of the illustra- tions. Our special thanks go to George Boehlert and Ellen Flentye (Scripps Institution of Oceanog- raphy) for providing the scanning electronmicro- graphs, and to John Fitch (California Department of Fish and Game), Edward Houde (University of Miami), David Kramer (National Marine Fisheries Service, La Jolla), and Sally Richardson for their critical review of the manuscript. LITERATURE CITED ABOUSSOUAN, A. 1968. Oeufs et larves de Teleosteens de I'Ouest africain VII. Larves de Syacium guineensis (Blkr.l IBothidae], Bull. Inst Fondam. Afr. Noire, Ser. A Sci Nat. 30:1188-1197. AGAS.SIZ. A., AND C. O. WHITMAN. 1885. Studies from the Newport Marine Laboratory. XVI. The development of osseous fi.shes, I , The pelagic stages of young fishes. Mem. Mus. Comp. Zool Harv. Coll. 14. 56 P AHL.STROM. E. H.. AND H. G. MOSEK. 1975. Distributional at'.as of fish larvae in the Cahfomia Current region: Flatfishes, 1955 through 1960. Calif. Coop. Oceanic Fish, Invest. Atlas 23. text vii-xix, 207 distribution charts. AHL.STROM, E. H., J. L, BUTLER, AND B. Y. SUMIDA. 1976. Pelagic stromateoid fishes (Pisces, Perciformes) of the eastern Pacific: Kinds, distributions, and early life histories and observations on five of these from the north- west Atlantic. Bull. Mar. Sci. 26:285-401. AMAOKA, K. 1970. Studies on the larvae and juveniles of the sinistral flounders - I. Taeruopsettn ocellata (Giinther). Jpn. J- Ichthyol. 17:95-104, 1971. Studies on the larvae and juveniles of the sinistral flounders — II. Chascanopsetta lugiibris. Jpn J Ichthyol. 18:25-32. 1972. Studies on the larvae and juveniles of the sinistral flounders— III. Laeops kilaharae. Jpn. J. Ichthyol. 19:154-165, 1973. Studies on the larvae and juveniles of the sinistral flounders — IV. Arnoglossusjaponiciis. Jpn, J. Ichthyol. 20:145-156. B AILEY, R, M. J. E. FITCH, E. S. HERALD, E. A. LACHNER, C. C. LINDSEY, C, R, ROBINS, AND W, B. SCOTT, 1970, A list of common and scientific names of fishes from the United States and Canada. 3d ed. Am. Fish. Soc, Spec. Publ. 6, 150 p. Bell, R. R. 1971. California marine fish landings for 1970 Calif Dep Fish Game, Fish Bull, 154:33-34, Bruun, a, F, 1937. Chat^canopsetta in the Atlantic; a bathypelagic oc- currence of a flat-fish, with remarks on distribution and development of certain other forms. Vidensk. Medd Dan. Naturhist. Foren. Kbh. 101:125-135. BUDD, P. L. 1940. Development of the eggs and early larvae of six California fishes. Calif. Div. Fish Game, Fish Bull. 56. 50 p. Clothier, C. R. 1950. A key to some southern California fi.shes based on vertebral characters. Calif Div. Fish Game, Fish Bull, 79, 83 p, DEVI, C, B, L 1969. Occurrence of larvae of Pseudorhomhus elevatus Ogilby (Heterosomata— Pisces! along the south-west coa.st of India. Proc. Indian Acad. Sci. 70(Sect. Bi: 178-1 86 142 SUMIDA ET AL EARLY DEVELOPMENT OF SEVEN FLATFISHES §■1 Sri. E x: E 8 n E CSJ w o CO £ E o o o o en C\J ^^ O) E OJ r~ C71 o o OJ SI .- o A CD O >, ^ O '- Q. C\J O 3 a.S cn *:■ o >'5- o.? E Qji=>y_j c C3 i» is a> &E E . CD Q. 3J E get: jb'DC-ocotDSE'OcnQ.ccj 3 c i;S CO , ) ii o t o S % r) 4 S E CVJ o o o (N CVJ — (N 4 O) o Q. (N Q. y 0) ° n O E ' o 2 Q. "Cl i- >,S X So I E sag 6 „ = in "> y o >* a> rrsssc Ss€oE= « C C CO O CT3 A -C CJ S ^"SScDC"^ CD£5<"Q.p«,E- 2 ran a ! E c cQ (0 T3 — D C CB - o 0) m — o u) ra o ^ ™ -^ A C ™ i3 c o e E (0 . 1 (D J ^0 13 . . £ d (D 03 ■_! = i: o o c 0) £ ^ £ o -. 2^ ^ S-, "c o in c c o-m ^ a> — ^ TO 0) ^• "J E Q) J= ii o _ i ■D ro o ■D 1 >- l/i 3 ro o o g 8 O o Q. 5 o c 3 (/) c S o "O X o o o ro c ro ^ ro Q- c J3 Q. to ro 2 T3 -D O C O J£ t '^ = '^ raJ: > re s So -2 ills O o cn ^ — ~ Q) C -O "3 "D ■- ra Q) "" f 3 S E S g o o CD CD cn Q, g" S ^iS ? CD ^5 o i" ro D «55S 143 FISHERY BULLETIN VOL. 77, NO. 1 EHRENBAUM, E. 1905. Nordisches Plankton. Zoologischer Teil. Erster Band: Eier und larven von Fischen. 1905 p. 1-216 Lab- ridae through Pleuronectidae, 1909 p. 217-414 Gadidaeto Amphioxidae. Reprinted 1964 A. Asher and Co.. Amster- dam. ELDRIDGE. M. B. 1975. Early larvae of the diamond turbot.Hypsopsetla gut- tulata. Calif. Fish Game 61:26-34. Fierstine, H. L., K. F. Kline, .\nd G. R. G.arman. 1973. Fishes collected in Morro Bay. California between January, 1968 and December, 1970. Calif. Fish Game 59:73-88. Fitch, J. E. 1963. A review of the fishes of the genus Pleuronichthys. Los Ang. Cty. Mus. Contnb. Sci. 76, 33 p. FREV, H. W. leditori. 1971. California's livmg marme resources and their utili- zation. Calif Dep. Fish Game, 148 p Gates, D. E., and h. w. fkey. 1974. Designated common names of certain marme or- ganisms of California. Calif Dep. Fish Game, Fish Bull 161:55-90. GINSBURG, I. 1952. Flounders of the genus Paralichthys and related genera in American waters. U.S. Fish Wildl. Serv., Fish Bull. 52:267-351, GUTHERZ, E. J. 1970. Characteristics of some larval bothid flatfish, and development and distribution of larval spotfin flounder, Cyclopsetta ftmhnata (Bothidael. U.S. Fish Wildl. Serv.. Fish. Bull. 68:261-283. HOLLISTER, G. 1934. Clearing and dyeing fish for bone study. Zoologica iN.Y.) 12:89-101. Holt, E. W. L. 1893. Survey of fishing grounds, west coast of Ireland. 1890-91: on the eggs and larval and post-larval stages of teleosteans. Sci. Trans. R. Dublin Soc, Ser. 2, 5, 121 p. HUBBS. C. L. 1928. A checklist of the marine fishes of Oregon and Washington. J. Pan-Pac. Res Inst. 3(3):9-16. HUBBS, C. L., AND Y. T. CHU. 1934. Asiatic fishes iDiplopnon and Laeops) having a greatly elongated dorsal ray in very large postlar- vae. Occas. Pap. Mus. Zool., Univ. Mich. 299. 7 p. KRAMER, D., M. J. KALIN, E. G. STEVENS, J. R. THRAILKILL. AND J. R. ZWEIFEL. 1972. Collecting and processing data on fish eggs and lar- vae in the California Current region. U.S. Dep. Com- mer., NCAA Tech, Rep. NMFS CIRC. 370. 38 p. Leonard, S. B. 1971. Larvae of the fourspot flounder, Hippoglossina ob- lunga I Pisces: Bothidae), from the Chesapeake Bight, western North Atlantic. Copeia 1971:676-681. Mr.'\LLI.STER, R. 1975. California marine fish landings for 1973. Calif Dep. Fish Game, Fish Bull 163:33 MILLER, D. J.. AND R. N. LEA. 1972. Guide to the coastal marine fishes of California. Calif Dep. Fish Game, Fish Bull. 157, 235 p., 1976 adden- dum, p. 237-249 in reprint edition. Div. Agric. Sci., Univ. Calif, Sale publ. 4065, 249 p. MILLER, D.. AND R. R. MARAK. 1962. Early larval stages of the fourspot flounder, Para- lichthys ohiongus Copeia 1962:454-455 MITO, S. 1961 Pelagic fish eggs from Japanese waters — I. Clu- peina, Chanina, Stomiatina, Myct/)phida, Anguillida, Be- lonida and Syngnathida. [In Jpn., Engl, summ.j Sci. Bull. Fac. Agnc, Kyushu Univ. 18:285-310 1962. Pelagic fish eggs from Japanese waters — V. Cal- lionymina and Ophidiina, [In Jpn., Engl, summ.] Sci. Bull. Fac Agnc. Kyushu Univ 19:377-380. 1963. Pelagic fish eggs from Japanese waters — IX. Echeneida and Pleuronectida Jpn. J. Ichthyol. 11:81- 102. MOSER, H. G., AND E. H. AHLSTROM. 1970. Development of lantemfishes (family Myctophidae) in the California Current Part I. Species with narrow- eyed larvae. Bull. Los Ang. Cty. Mus. Nat. Hist. Sci. 7. 145 p. MOSER. H. G., E. H. AHLSTROM, AND E. M. SANDKNOP. 1977. Guide to the identification of scorpionfish larvae (family Scorpaenidaei in the eastern Pacific with com- j parative notes on species of Sebastes and Heticolenux from I other oceans. U.S. Dep. Commer.. NCAA Tech. Rep. ' NMFSCirc. 402, 71 p. NIELSEN, J. G. 1963. Descnption of two large unmetamorphosed flatfish- larvae (//e^erosomato), Vidensk. Medd, Dan. Naturhist. Foren Kbh. 125:401-406 Norman. J. R. 1934. A systematic monograph of the flatfishes (Hetero- somata). Vol. I: Psettodidae, Bothidae, Pleuronec- tidae. Br. Mus. (Nat. Hist.), Lond., 459 p. Okiyama, M. j 1967 Studies on the early life history of a flounder, I Paralichthys olivaceus (Temminck et Schlegel). 1. De- * scriptions of postlarvae. Bull. Jpn. Sea Reg. Fish. Res. Lab 17:1-12. OLIPHANT, M. S. 1973. California marine fish landings for 1971. Calif. Dep. Fish Game, Fish Bull. 159:32-33. ORTON, G. L. 1953. Development and migration of pigment cells in. some teleost fishes. J. Morphol. 93:69-99. ORTON, G. L., AND C. LIMBAUCH. 1953. Occurrence of an oil globule m eggs of pleuronectid flatfishes. Copeia 1953:114-115. PINKAS. L. 1974. California manne fish landings for 1972. Calif Dep. Fish Game, Fish Bull. 161:32-33. Sanzo. L. 1915. Contributo alia conoscenta dello sviluppo ncgli Scopelini Muller iSuuru.s^r/seus Lowe, C/i/orop/iMa/mus agassuii Bp. ed Aiilopus filamentosus Cuv,). R. Com. Talassogr. Ital Mem. 49, 21 p. 1931. Uova, larvae e stadi giovanih di Teleostei Sottor- dine: Stomiatoidei Fauna Flora Golfo Napoli Monogr. 3842-92 1933 Uova, larvae e »tadi giovanili di Teleostei Famiglia Macruridae Fauna Flora Golfo Napoli Monogr. 38:255-265. SMITH. W G., AND M. P FAHAY. 1970. Descriptionof eggs and larvae of the summer floun- 144 SUMIDA ET AL EARLY DEVELOPMENT OF SEVEN FLATFISHES der. Paraiichthys dentatus. U.S. Fish Wildl Serv,. Res, TOWNSEND, L. D. Rep. 75, 21 p. 1936. Variations in the meristic characters of flounders STARKS, E. C, AND W. F. THOMPSON. from the northeastern Pacific. Rep. Int. Fish. Comm. 11, 1910. A review of the flounders belonging to the genus 24 p Pleuromchthys. Proc, U.S. Natl. Mus. 38:277-287. WHITE, W F, TaKITA, T.. AND S. FUJlT.i^. 1977, Taxonomic composition, abundance, distribution, 1964. Egg development and prolarval stagesoftheturbot, and seasonality offish eggs and larvae in Newport Bay, Pleuromchthys cornutus (Temminck et Schlegeli. [In California, M, A. Thesis, California State Univ., Fuller- Jpn., Engl. summ.I Bull. Jpn. Soc. Sci. Fish. 30:613-618. ton, 107 p. 145 ASSOCIATIONS OF TUNA WITH FLOTSAM IN THE EASTERN TROPICAL PACIFIC Paul R. Greenblatt' ABSTRACT The fishing record for flotsam-associated tuna in the eastern tropical Pacific was examined. The rivers of Central America are probably the major source of flotsam. Correlation analysis ofthe number of sets occurring in an area indicates that unassociated tuna and flotsam-associated tuna are related. The number of sets made on floating objects has increased dramatically since 1971. The percentage of flotsam-associated sets has increased, indicating that flotsam-associated sets are more important to the tuna fishery than in 1963. The catch per set of tuna associated with flotsam has also increased markedly since 1967. Analysis of length-frequency data indicate that, on a single set basis, tuna fork length is more variable in sets associated with flotsam than with unassociated schoolfish sets. Results of the length-frequency analysis support the idea that flotsam aggregates tuna. The catch of the eastern tropical Pacific tuna fishery consists of mostly yellowfin tuna, Thunnus albacares, and skipjack tuna, Katsuwonus pelamis. The catch is frequently categorized by the conditions under which the purse seine set is made. Scott 1 1969) made a major distinction be- tween associated schools and unassociated schools. Associated schools are caught either in "porpoise sets" (sets associated with porpoise) or "floating object sets" (sets associated with logs or other flotsam). Unassociated schools are caught in "night sets" (sets made at night with the aid of bioluminescence) and "schoolfish sets" (schools seen and set upon during the day). Night sets compose a very small proportion of total sets and will not be discussed in this paper. Porpoise sets catch mostly yellowfin tuna. Floating object sets and schoolfish sets catch yellowfin and skipjack tuna, either as pure or mixed species. Little is known about the attraction of tuna to flotsam. Gooding and Magnuson (1967) and Hunter and Mitchell (1968) observed fish gather- ing around flotsam. These authors attracted some tuna to their flotsam, but never large schools. Tuna were a minor portion of the observed fish assemblages. Hunter and Mitchell ( 1968) postula- ted a connection between schooling behavior and the attraction of fish to flotsam. They concluded that flotsam had the function of providing (p. 27) "... a visual stimulus in an optical void." Gooding 'Southwest Fisheries Center La Jolla Laboratory, National Marine Fisheries Service. NOAA, La Jolla. Calif; present ad- dress: Code A-008, Scripps Institution of Oceanographv. Univer- sity of California, La Jolla, CA 92093. Manuscript accepted August 1978 FISHERY BULLETIN VOL. 77, NO, 1. 1979. and Magnuson ( 1 967) concluded that fish gathered around floating objects at sea primarily because the objects provided shelter from predation. It may be possible that the same factors attracting small- er fish also attract large tuna schools. This paper examines historical tuna fishery data on the catches of yellowfin and skipjack tuna associated with floating objects in the eastern tropical Pacific from 1963 to 1975. The objectives ofthe paper are to 1 ) establish the main sources of flotsam, 2) determine if there is a connection be- tween various set types, 3) see if flotsam- associated sets have become more important to the tuna fishery, 4) determine if the catch rate on flotsam-associated sets has changed, and 5) assess whether flotsam does aggregate tuna schools. METHODS Since the catch of tuna associated with flotsam depends on the presence of tuna, flotsam, fisher- men, strength of attraction, and suitable fishing conditions, I examined each factor in light ofthe published literature and available fishery data from the eastern tropical Pacific tuna fishery. The Inter- American Tropical Tuna Commission ( lATTC) collects information from tuna fishermen operating in the eastern tropical Pacific. Informa- tion collected in logbooks includes date and loca- tion of sets, catch of various species, type of set, and environmental conditions. Although these logbooks remain confidential, it is possible to ob- tain summaries of the information for certain time-area strata. During the beginning portion of 147 FISHERY BULLETIN VOL 77, NO. 1 the year, yellowfin tuna fishing is unregulated. After a quota is reached (Table 1), all yellowfin tuna fishing, except for special allowances must be outside the Commission's Yellowfin Regulatory Area (CYRA) (Figure 1). Due to special rules (see Table l. — Yellowfin quota (thousands of short and metric tonsi. closure data, and annual total catch (thousands of short and metric tons) for the Commission's Yellowfin Regulatory Area, taken from Calkins ( 1976).' Metric tons are given in parenth- eses. Quola Closure Annual Year Quota + inaement^ dale total catch 1966 79 3 ( 71 9) Sept 15 91 1 ( 82 6) 1967 84.5 ( 76 6) June 24 89 6 ( 81 3) 1968 106 0( 96 1) June 18 1146 (1039) 1969 120 (108 8) Apr 16 1265 (1147) 1970 1200(108 8) Mar 23 1426 (129 3) 1971 140 0(127 0) Apr 9 1139 1103 3) 1972 120 0(108 8) 140 0(127 0) Mar 5 152 5(138 3) 1973 130 (117 9) 1600(145 1) Mar 8 177 8 (161 3) 1974 175 (158 7) 195 0(176 9) Mar 18 191 3 (173 5) 1975 175 0(158 7) 1950(176 9) Mar 13 1772 (160 7) 1976 175 0(158 7) 1950(176 9) Mar 27 205 5(186 4) The 1976 fishrng year (through August . 33rd meeting of the Inter-American Tropical 'Calkins. T P 1976 30) Background Paper No Tuna Commission ^The Director ot lATTC may increment the established quota, allowing more yellowlm tuna to be caught Figure l. — Eastern tropical Pacific fishing area divided into three nearshore areas lAreas l-3i and one offshore area (Area 4). The heavy line to the west delimits the boundary' for the Com- mission Yellowfin Area (CYRA). The average number of flotsam- associated sets from 1972 to 1975 by 5" squares is shown. Data represent the unregulated fishing period isee text). Inter-American Tropical Tuna Commission 1967-1975), any detailed reporting of regulated data would compromise the confidentiality of the data; hence, only unregulated catch and number of sets within the CYRA summarized by month and 5' square for 1963-75 were made available to me. The total number of unregulated sets during the 13 yr was approximately 161,000 of which 8,190 were associated with flotsam. In addition, the lATTC provided the total number of flotsam- associated sets occurring each year ( Figure 2 ). One sees that the major trends in the number of sets are contained in the block of unregulated data. NOAA's Southwest Fisheries Center (SWFC) periodically sends technicians aboard tuna sein- ers. These technicians record details about set type, catch, environmental conditions, as well as the fork length (centimeters) of tuna sampled from individual sets. Fork lengths of yellowfin and skip- jack tuna wereonly available for a limited number of sets made in 1973-75. The location of fork length measurements are given in Table 2. Single set catch data were collected by SWFC technicians in 1974-76 (unpubl. data^). ^Unpubl. data on file at the Southwest Fisheries Center. Na- tional Marine Fisheries Service, NOAA, P.O. Box 271, La Jolla. CA 92038. 2,000 - 1963 1965 1967 1969 1971 1973 1975 YEAR Figure 2. — Total number of flotsam-associated sets made in the eastern Pacific and number of unregulated flotsam-associated sets made in the CYRA, 1963-75. 148 GREENBLATT ASSOCIATIONS OF TUNA WITH FLOTSAM Table 2. — Spatial distribution of fork length measurement ( centimeters) of yellowfin and skipjack tuna m the Commission's Yellowfin Regulator>- Area. 1973-75. C YRA subareas are shown in Figure 1. (Source of data, SWFC.) CYRA subarea Number of sets where tork lengtti was measured 1 56 2 12 3 14 4 29 Monthly rainfall in Central America was calcu- lated by averaging the stations reporting to the Environmental Data Service (U.S. Department of Commerce 1963-1975). In order to achieve the objectives of this paper, the data obtained from lATTC and SWFC were examined and analyzed in several ways. The main sources of flotsam were inferred by examining the average distribution of flotsam-associated sets and consideration of the average surface circula- tion. Two methods may be used to determine if differ- ent set types are related: correlation of set types occurring in an area and comparison of fork length distributions (length-frequency gi-aphs) stratified by species and set type. Spearman's rank correla- tion coefficient (Siegel 1956) was calculated to ex- pose possible correlations of numbers of sets. Fork length distributions were weighted by the catch in each set. A high positive correlation between set types occuring in an area would indicate a rela- tionship between set types. Similar looking length-frequency distributions would serve as further evidence that set types are related. An increase in the percentage of flotsam- associated sets would be evidence that flotsam- associated sets have become more important to the fishery. The CYRA was subdivided into three nearshore areas and one offshore area (Figure 1). Stratifying the number of flotsam-associated sets by area allows the determination of area effects. Hence, the importance of flotsam to the fishing industry may be determined by the percentage of flotsam-associated sets occurring each year and stratifying the number of flotsam-associated sets by area. Average rainfall was tabulated to determine if any connection existed between river runoff and the number of flotsam-associated sets. Catch rate is an indicator of the importance of flotsam-associated sets to the tuna fishery. Calcu- lation of the average yearly catch per set (includ- ing zero catch sets) for different set types should demonstrate any trends as well as the relative value of making one set type over another. Calkins (1965) examined tuna length distribu- tions from single sets in the eastern tropical Pacific, finding that single unassociated schoolfish sets caught tuna of a relatively uniform size (i.e., small variance in length). If the fish caught in flotsam-associated sets represent aggregations of solitary tuna, portions of schools, or several schools, then one would expect the variance of tuna length to be greater than for unassociated schools. In order to examine if floating objects act as aggregators, length-frequency data were strat- ified by species and set type. Mean length and standard deviation were calculated on a single set basis for each category and compared using Kruskal-Wallis one-way analysis of variance by ranks (Siegel 1956). If flotsam does aggregate tuna, one would expect more of the larger flotsam-associated sets than unassociated sets. Differences in catch distribu- tion were observed by plotting histograms of tons of tuna caught per set stratified by year and set type and by calculating catch per successful set for each year and set type. The single set catch data, collected by SWFC technicians, existed for the 1974-76 period. RESULTS The availability of logs or other flotsam in an area are determined by the source of the flotsam and the currents in the area. Large rivers flow into the Pacific from southern Mexico (lat. 20°N) and continue down the coast of South America (to lat. 20°S). These rivers are capable of releasing many logs into the Pacific during the rainy season. SWFC and lATTC observers reported large densi- ties of logs near the Gulf of Tehuantepec (lat. 16°N, long. 100°W), the Gulf of Nicoya (lat. lO'^N, long. 85°W), and the Gulf of Fonseca (lat. 13°N, long. 87°W). The average yearly number of flotsam- associated sets in 1972-75 were plotted by 5° squares (Figure 1). In general, most flotsam- associated sets occurred in Areas 1 and 2. Most of the offshore flotsam-associated sets (i.e., Area 4) occurred quite close to Areas 1 and 2. Area 3 did not have large numbers of flotsam-associated sets. If the main source of logs and other flotsam is the rivers of Central America, then it is important to examine the major current patterns in the eastern tropical Pacific to determine if the currents can 149 FISHERY BULLETIN: VOL 77, NO 1 explain the observed distribution of flotsam- associated sets. The average currents in the eastern tropical Pacific, as derived from ship's drift data, were de- termined by Wyrtki (1965). From January until May, the California Current is strong. Circulation near Area 3 is to the south. Circulation near Areas 1 and 2 is gyral. From May to July, both the Equatorial Countercurrent and the California Current are relatively stong. During this period, most countercurrent water turns north and flows along the coast of Central America. Area 3 has a northern and southern flow, the northern flow along the coast. Area 1 maintains its gyral flow. From August through December, the Equatorial Countercurrent is well developed. Circulation in Area 3 is to the south. Area 2 maintains its north- western flow along the coast and Area 1 flow main- tains a gyral pattern. If logs disperse mainly from the Gulf of Nicoya, the Gulf of Tehuantepec. and the Gulf of Fonseca, then the gyral circulation in Area 1 would tend to maintain logs and other flotsam in the area for a considerable time. The northwest coastal current in Area 2 could trans- port flotsam through Area 2 and during part of the year into Area 3. Since the North Equatorial and South Equatorial Currents are rather strong, one would not expect floating objects to persist in Area 4 except near the boundaries with Areas 1 and 2. Hence the location of large rivers and the system of currents is reasonably consistent with the geo- graphical distribution of flotsam-associated sets. In order to compare different set types, Spear- man's rank correlation coefficient was calculated. For each 5° square in the C YRA, the total numbers of flotsam-associated sets, porpoise-associated sets, and unassociated schoolfish sets were tabu- lated for each year. These totals were ranked and the ranks were correlated. Only 5° squares where at least 10 sets occurred were used in calculating correlations. When a minimum of 40 sets was used as the criterion for including a 5° square, the corre- lations were qualitatively the same as with the 10 sets criterion. The results (Table 3) show that a significant positive correlation exists between number of sets on unassociated schoolfish and flotsam-associated tuna. Porpoise sets were uncor- rected with other set types. The above results indicate that fish caught as- sociated with flotsam tended to be caught in the same area at the same time as unassociated school fish. Examination of available length-frequency data on a species basis, weighted by the catch in T.^BLE 3. — Spearmans rank correlation between three types of sets by year. Number of sets/5° square. (Source of data: I ATTC . ) Year N Unassociated schoollisri and porpoise- associated Unassociated schoolfish and flotsam^ associated Porpoise and flotsam- associated 1963 29 -0,0008 5421" 2538 1964 27 0375 1581 08138-- 1965 25 ■0 1597 3498' 1318 1966 28 ■01110 03513- 02914 1967 24 ■92379 4621- ■0,2255 1968 24 ■0 1951 1886 03463- 1969 25 -0 1523 05957-- 02294 1970 27 ■0 0088 03529- ■00173 1971 26 0803 5819" 0,2398 1972 32 ■0 0200 05277-- ■00558 1973 34 0523 3086- 0,1796 1974 27 0-0168 04847" 0,0001 1975 33 02444 0,5139" 00526 •Si. "Si gnificant at Ps gnrticant at Ps 05 ;0 01 each set (Figure 3), indicated that unassociated schoolfish and flotsam-associated yellowfin and skipjack tuna had very similar length-frequency distributions. The length-frequency information and the correlation analysis support the idea that unassociated tuna and flotsam-associated tuna are related. Flotsam, acting as an attractant, may aggi-egate tuna that would otherwise be caught in unassociated sets. The number of flotsam-associated sets has in- creased dramatically since 1971 (Figure 2). The trend in percentage of flotsam-associated sets (Fig- ure 4) indicates that flotsam-associated sets have increased in importance to the fishery. Stratifying the number of unregulated flotsam-associated sets by area (Figure 5i shows that the trend of more flotsam-associated sets is not an area effect. All areas, except Area 3, have shown a marked in- crease in number of flotsam-associated sets. Area 3 does not show an increase because logs are only deposited in this region during a limited portion of the year. In January-May, the near surface cur- rent in Area 3 is to the south (Wyrtki 1965), cut- ting off the source of logs that wash down the rivers of Central America. Also, good fishing often occurs in Area 3 during the later months of the year, a period not included in my unregulated data. It appears that the increase in flotsam- associated sets in recent years was not caused by discovery of new areas with abundant flotsam but rather by an increase in fishing effort on flotsam in all areas but Area 3. Average rainfall in Central America was tabu- lated (Table 4) to see if there was a correlation between river runoff and the number of flotsam- associated sets. Comparison of number of flotsam-associated sets and rainfall revealed only 150 GKEENBLATT ASSOCIATIONS OF TUNA WITH FLOTSAM SKIPJACK SCHOOLFISH SKIPJACK ASSOCIATED WITH FLOTSAM 30 *0 50 60 'G 80 90 100 ilO l£0 tJO 30 40 50 60 '0 80 9C' lOO mO 20r Figure 3— Length-frequency distribu- tions of yellowfin and skipjack tuna caught in unassociated schoolfish and flotsam-associated sets Data collected 1973-75 in the CYRA (see Table 2). YELLOWFIN SCHOOLFISH I I I I I I 'I FORK LENGTH (cm) YELLOWFIN ASSOCIATED WITH FLOTSAM 20 1- TABLE 4. — Average yearly rainfall (centimeters) in Central America in 1963-75, (Source; U.S. Department of Commerce.) 1963 64 65 66 67 68 69 70 71 72 73 74 75 YEAR Figure 4. — Percentage of total unregulated sets that were as- sociated with flotsam in the CYRA. 1963-75. small similarities, indicating that the supply of suitable flotsam was not greatly influenced by rainfall. Comparing the average catch per set of different set types indicates the relative importance of each set type to the fishery as well as showing trends in the catch rate (Figure 6). All set types had similar catch rates in 1963-66. Porpoise sets and flotsam- associated sets gave much higher catch per set than unassociated sets in 1971-75. One sees that flotsam-associated sets have been the most valu- able set type for the tuna fisherman since 1971. Average yearly Average yearly Year rainfall Year rainfall 1963 139 1970 163 8 1964 136,4 1971 145-5 1965 136 9 1972 145-6 1966 158,5 1973 161 4 1967 151,7 1974 172 3 1968 177J 1975 151 1969 177 2 Fork length data was stratified by set type and species. The mean length, standard deviation, and sample size were calculated on a single set basis (Table 5). The average standard deviation of fork length of yellowfin and skipjack tuna associated with flotsam was larger than the standard devia- tion found in unassociated sets, though the mean fork length of flotsam-associated sets was smaller. The probability of getting the results shown (Ta- ble 5) by chance was calculated using Kruskal- Wallis one-way analysis of variance (Siegel 1956: 184) (Table 5 1. The greater variability of fork length of flotsam-associated tuna supports the hypothesis that flotsam aggregates tuna. The yellowfin and skipjack tuna catch distribu- tion on flotsam-associated sets was compared with unassociated schoolfish sets. The average catch per successful set was calculated and the data were plotted as histograms of tonnages using an arbitrary interval of 5 tons (Figure 7). The main 151 FISHERY BULLETIN VOL 77. NO, 1 Figure 5— Number of unregulated flotsam-associated sets per month by area. 1963-75. of;^,Ayv.,-,/, ^l\ A A -iOO FLOTSftM ASSOCIATED U-- 265 CPSS = 24 07 {21 63) 1975 UNflSSOCIATEO SCHOOLFISH CPSS = 16 07 (14 5B) I hi n n r 1975 FLOTSAM ASSOCIATED N^20e CPSS = 27 30 124 76) njfrh-rw. 1976 UNASSOCIATED SCHOOLFISH N = 98l CPSS = 21 21 (19 24) 25 50 75 >I00 \m. _a — q 1 SHORT TONS 1976 FLOTSAM ASSOCtATED N= 550 CPSS = 26 04 (23 621 1 1 1 nhp-ii-n r 25 50 7l> SHORT TONS 153 FISHERY BULLETIN VOL 77. NO. 1 CYRA. Although they had small numbers of sets, the percentage of successful flotsam-associated sets from 1962 to 1966 was 67.6'*. Changes in percentage of successful sets can not adequately explain the increased catch per set. No satisfactory explanation for the increase in catch per flotsam-associated set has been found. Overall increases in abundance or increased skill of the fishermen can not explain the increase. The above factors may account for some of the increase. Technological advances may account for the in- creased catch rate. It is also reasonable to believe that fishermen have learned to catch flotsam- associated tuna more efficiently and the residence time of tuna with flotsam has increased since 1967. Changes in catch per set on flotsam-associated sets may have been due to technological advances such as bigger nets. If technological advances can explain the increased catch per set on flotsam, then either the catch per set on unassociated schoolfish should have also increased or sets as- sociated with flotsam prior to the technological advances must have caught a low proportion of potential catch. Nets have increased in size, perhaps increasing the probability of catching yel- lowfin and skipjack tuna which may aggregate around flotsam. It is possible that bigger nets could account for increased catch/set of flotsam- associated sets without likewise affecting catch/ set on unassociated schoolfish sets. Fishermen often will drift with logs for consid- erable time, waiting for tuna aggregations to reach an optimal size before setting the net. The spread of such behavior throughout the fleet could cause the overall catch per set of flotsam- associated tuna to increase. Adequate data for testing this "increased knowledge" hypothesis was unavailable. The marked changes occurring in flotsam- associated tuna catch in 1963-75 coincided with a large increase of effort and technology in the porpoise-associated fishery (Green et al. 1971). It is hypothesized that the increased effort and technology in the porpoise-associated fishery may have been related to changes in the catch rate of tuna schools associated with flotsam. When purse seiners set on porpoise, there is often an incidental kill of the marine mammals. Due to recent technological advances, the porpoise kill has been reduced, but in earlier years of the porpoise-associated fishery (the mid-1960's) por- poise mortality was higher (Southwest Fisheries Center^'). This incidental kill may have reduced the porpoise population. The porpoise-associated fishery first developed near shore and thus the nearshore porpoise stocks have been affected for a longer time than offshore stocks. One may reason- ably speculate that, on a species basis, nearshore porpoise stocks have been affected more by inci- dental kills than offshore porpoise stocks. The bond between tuna and porpoise is not un- derstood. It is possible that the mechanisms in- volved in the association of tuna with porpoise is similar to those responsible for their association with flotsam. Tuna associated with flotsam are, on the average, smaller than tuna associated with porpoise (Calkins 1965, tables 2 and 9; Sharp''). Knudsen (1977) gave some evidence that tuna caught in areas where porpoise fishing predomi- nates were generally older and larger than in tra- ditional schoolfish areas. Size overlap, however, did occur (Calkins 1965). Assuming that the number of porpoise schools have declined, the probability of tuna encountering porpoise schools has decreased. The probability of tuna aggregated near flotsam encountering porpoise schools has also decreased. Thus, as a result of decreased en- counter rates with porpoise (slower transition from flotsam to porpoise), the size of the aggrega- tions of tuna near flotsam have increased. In conclusion, the most likely sources of flotsam are the large rivers of Central America. Indirect evidence indicates that tuna caught in unas- sociated schoolfish sets are from the same popula- tion as tuna caught associated with flotsam. It appears that the increase of flotsam-associated sets from 1963 to 1975 was due to an increased interest by fishermen and hence an increased fishing effort on floating objects. The observed in- crease in catch per set may have been a biological change rather than a change in fishing technology or skill. ACKNOWLEDGMENTS I would like to express my thanks to John Hunter who provided guidance in several phases of this study. His comments were extremely help- "Southwest Fisheries Center. 1976. Report of the Work- shop on Stock Assessment of Porpoises Involved in the Eastern Tropical Pacific Yellowfin Tuna Fishery. SWFC Adm Rep, LJ-76-29, 54 p. Southwest Fisheries Center. La Jolla, CA 92038. "G. Sharp, Inter-American Tropical Tuna Commission. Southwest Fisheries Center. La Jolla, CA 92038, pers. commun April 1977. 154 GREENBLATT ASSOCIATIONS OF TLINA WITH FLOTSAM ful. Richard McNeely first suggested the possible interaction of porpoise and flotsam-associated tuna. The Inter-American Tropical Tuna Com- mission provided much of the data. William Flerx and Richard Charter provided insight into the op- eration of the fishery. Gary Sharp provided useful information about yellowfin tuna. Rainfall data were obtained from Eric Forsbergh. William Lenarz, Douglas Chapman, and Robin Allen re- viewed the paper and offered constructive com- ments. LITERATURE CITED Bayliff, W. H., and C. J. Orange. 1967. Observations on the purse seine fishery for tropical tunas in the eastern Pacific Ocean. Inter-Am. Trop. Tuna Comm., Intern. Rep. 4, 79 p. Calkins, T. P. 1965. Variation in size of yellowfin tuna iThunnus alba- cares) within individual purse-seine sets. [In Engl, and Span.) Inter-Am, Trop, Tuna Comm., Bull. 10:461-524. GOODING. R. M., AND J. J. MAGNUSON. 1967. Ecological significance of a drifting object to pelagic fishes. Pac. Sci. 21:486-497. Green. R. E., W. F, Perrin, and B, P, Petrich, 1971. The American tuna purse seine fishery. In H. Kristjonsson (editor), Modern fishing gear of the world. Vol. 3. p, 182-194, Fishing News (Books) Ltd.. Lond, GREENBLATT, P, R, 1977. Factors affecting tuna purse seine fishing ef- fort, ICCATRep.Vol. VI(SCRS-1976). No, 1 Tropical spp,. p, 18-31. Hunter, J. R., and C. T. Mitchell, 1968. Association of fishes with flotsam in the offshore waters of Central America. U.S. Fish Wildl, Serv, Fish. Bull. 66:13-29. Inter-American Tropical Tuna Commission. 1967-1976. Annual Report, 1966-1975. Inter-Am. Trop. Tuna Comm., La Jolla, Calif KNunsEN. P. F. 1977. Spawning of yellowfin tuna and the discrimination of subpopulations, [In Engl, and Span.[ Inter-Am, Trop, Tuna Comm,, Bull, 17:117-169. PELLA, J. J., AND C. T. PSAROPULOS. 1975. Measures of tuna abundance from purse-seine oper- ations m the eastern Pacific Ocean, adjusted for fieet-wide evolution of increased fishing power, 1960-1971, [In Engl, and Span.] Inter-Am. Trop. Tuna Comm.. Bull, 16:281- 400, SCOTT, J, M, 1969, Tuna schooling terminology Calif Fish Game 55:136-140, SlEGEL, S. 1956. Nonparametric statistics for the behavioral sciences. McGraw-Hill Book Co,. N,Y , 312 p. U.S. DEPARTME.NT OF COMMERCE. 1963-1975. Monthly climatic data for the world, NOAA, Environ, Data Serv,, vol, 16-28, var, pagination, WYRTKI, K, 1965, Surface currents of the Eastern Tropical Pacific Ocean, [In Engl, and Span] Inter-Am Trop, Tuna Comm., Bull. 9:269-304. 155 DESCRIPTION OF LARVAE OF THE NORTHERN SHRIMP, PANDALUS BOREALIS, REARED IN SITU IN KACHEMAK BAY. ALASKA Evan Haynes' ABSTRACT Northern shrimp. Panda! us borealis. were reared in situ in Kachemak Bay. Alaska, from Stage I (first zoeali through Stage VIII (second juvenile). Each of the six larval stages and first juvenile stage is described and illustrated, and a bnef description is given for the second juvenile stage. Apparently larvae of P borealis in Alaska waters have at least one less stage than larvae of P. borealis in either British Columbia. Greenland, or Japan waters. Of the known larvae of the North Pacific Ocean, larvae of P- borealis are most similar morphologically to larvae of P goniurus but are separable from them by being slightly larger in size and, in zoeal Stages I-III, by bearing more setae on certain appendages, particularly the antennal scale and certain mouth parts. From Stage IV to megalopa, the rostrum of P. borealis has more dorsal teeth, the second pereopods are more developed, and the pleopods are fringed with more setae than for larvae ofP, goniurus -The criterion of the lack of an outer seta on the maxillule for distinguishing zoeae oi Pandalus from certain other Candea is shown to be invalid In 1972 the National Marine Fisheries Service began studies on the early life history of pandalid shrimp in Alaska waters with the initial objective of describing in detail laboratory-reared larvae of each pandalid species previously unverified. Two previous reports have described larvae of Pan- dalus hypsinotus Brandt reared in the laboratory (Haynes 1976) and P. goniurus Stimpson reared in situ in Kachemak Bay, Alaska (Haynes 1978). This report describes and illustrates each of the six larval stages and the first juvenile stage of north- ern shrimp, P. borealis KrOyer, and compares the stages obtained from rearing in situ with descrip- tions of pandalid shrimp larvae given by other authors. A brief description of the second juvenile stage is included. MATERIALS AND METHODS Rearing techniques were identical in all re- spects to those described in an earlier report on P. goniurus (Haynes 1978). Briefly, the technique consists of obtaining Stage I larvae of known parentage in the laboratory, then rearing the lar- vae in flasks submerged at sea. Larvae from plankton were also reared in flasks at sea in an identical manner beginning with Stage I. Larvae reared in flasks were compared with larvae from 'Northwest and Alaska Fisheries Center Auke Bay Laborato- ry. National Marine Fisheries Service, NOAA, P.O. Box 155, Auke Bay. AK 99821. plankton for verification of sequence of stage and larval morphology. Because the paired appendages of the larvae are symmetrical, only one member (the left) is figured. An exception is the mandibles which are drawn in pairs. Orientation of surface of appendages in the figures is given in the figure legends. The figures of the appendages are in part schematic and repre- sent typical setal counts. Variability in setation or segmentation of paired appendages, such as the difference in number of carpal joints between the left and right second pereopods in the megalopa, is mentioned in the text. Carapace length refers to the straight-line distance from posterior margin of orbit to middorsal posterior margin of carapace. Total body length refers to the distance from tip of rostrum to posterior margin of telson, not includ- ing telson spines. Terminology, methods of measuring, techniques of illustration, and nomenclature of gills and appendages follow Haynes (1976). Comparison of larvae from plankton with cast skins from flasks was facili- tated by first clearing the larvae in W7c KOH. For clarity, setules on setae are usually omitted but spinulose setae are snown. STAGE I ZOEA Mean total length of Stage I (Figure lA) 6.7 mm (range 6.5-7.3 mm; 25 specimens). Live specimens characterized by orange color; conspicuous chromatophores throughout cephalothorax re- Manuscript accepted July 1978 FISHERY BULLETIN VOL 77. NO 1.1979 157 FISHERY BULLETIN VOL 77, NO 1 gion, especially in mouth parts; large chromatophore near tip of antennal scale, at base of telson, and at front of eye; smaller but distinct chromatophores on maxillipeds; ventral surface of each abdominal somite tinged orange; faint greenish hue at base of pereopods. Rostrum slen- der, spiniform, without teeth, about one-third length of carapace, projecting horizontally or slightly downward. Carapace with small, some- what angular dorsal prominence at base of ros- trum and smaller, rounded prominence near pos- terior edge. These two prominences occur in all zoeal stages. Pterygostomian spines present but usually hidden by sessile eyes. Three or four mi- 0. 5 mm Left Right 0. 25 mm 158 HAYNES DESCRIPTION OF PA.MDAI.i'S ROREALIS LARVAE nute spinules along ventral margin of carapace immediately posterior to pterygostomian spine I spinules not shown in Figure lA). These spinules usually occur in all zoeal stages but may vary in number from two to five not only between stages but among individuals within a given stage. ANTENNULE (Figure IB).— First antenna, or antennule, consists of simple unsegmented tubu- lar basal portion with heavily plumose seta termi- nally and distal conical projection with four aesthetascs: one long, one short, and two of inter- mediate length. 0.25 mm . 5 mm 0. 5 mm K 0. 5 mm Figure l. — Stage I zoea ofPandalus horealis: A, whole animal, right side; B. antennule, dorsal; C, antenna, ventral; D, mandibles (left and right), posterior; E, maxillule. ventral; F, maxilla, dorsal; G, first maxiUiped, lateral; H, second maxilliped, lateral; 1, third maxilliped, lateral; J, second pereopod, lateral; K, telson, dorsal. 159 FISHERY BULLETIN VOL 77. NO 1 ANTENNA (Figure IC).— Second antenna, or antenna, consists of inner flagellum (endopodite) and outer antennal scale (exopodite). Flagellum unsegmented, slightly shorter than scale, styliform, and tipped by spinulose spine. Antennal scale distally divided into six joints (the two prox- imal joints incomplete) and fringed with 19 heav- ily plumose setae along terminal and inner mar- gins; small seta occurs on outer margin at base of joints and another proximally near outer margin. Protopodite bears spinous seta at base of flagellum but no spine at base of scale. MANDIBLES (Figure ID).— Without palps in this and all succeeding zoeal stages. Incisor pro- cess of left mandible bears four teeth in contrast to triserrate incisor process of right mandible. Left mandible bears movable premolar denticle (lacinia mobilis) whereas right mandible bears two immobile premolar denticles. Truncated molar process of left mandible bears subterminal tooth that occurs throughout all zoeal stages. MAXILLULE (Figure IE).— First maxilla, or maxillule, bears coxal and basial endites and en- dopodite. Coxopodite (proximal lobe) bears stout seta near base, and eight spinulose spines termi- nally. Basipodite (median lobe) bears nine spinulose spines on terminal margin and large setose seta proximally. Endopodite originates from lateral margin of basipodite; bears three terminal and two subterminal setae, three of them sparsely plumose and remaining two spinulose. MAXILLA (Figure IF). — Second maxilla, or maxilla, bears platelike exopodite (scaphog- nathite) with 11 long, evenly spaced plumose setae along outer margin and one slightly longer and thicker seta at the slightly expanded proximal end. Endopodite gives indication of four partly fused segments and bears nine large plumose setae. Coxopodite and basipodite bilobed. Coxopo- dite bears 21 setae, 4 on distal lobe and 17 on proximal lobe. Basipodite bears eight setae on each lobe. Five setae, three on coxopodite (one on distal lobe and two on proximal lobe) and two on distal lobe of basipodite, bear row of little spines along entire length. An additional seta on proxi- mal lobe of coxopodite is especially spinulose. FIRST MAXILLIPED ( Figure IG i.— Most heav- ily setose of natatory appendages. Protopodite fully segmented; bears 7 setae on proximal seg- ment and 18 slightly smaller setae on distal seg- ment, 9 of them spinulose. Endopodite distinctly four-segmented; setation formula 4, 2, 1, 4. Exopo- dite a longer slender ramus segmented at base; bears two terminal and three or four lateral nata- tory setae. Epipodite a single lobe. SECOND MAXILLIPED (Figure IH).- Protopodite bisegmented; distal segment bears 10 sparsely plumose setae, no setae evident on prox- imal segment. Endopodite distinctly five- segmented, fourth segment expanded laterally; setation formula 7, 3, 1, 2, 4. A seta on segments 1 and 5 of endopodite and three setae on protopodite especially spinulose. Exopodite with 2 terminal and 11 or 12 lateral natatory setae. No epipodite. THIRD MAXILLIPED (Figure ID.— Protopodite bisegmented; distal segment bears four setae. Endopodite distinctly five-segmented; nearly as long as exopodite; setation formula 4, .5, 1, 1,2. Exopodite with 2 terminal and 14 lateral natatory setae. No epipodite. PEREOPODS— Poorly developed, directed under body somewhat anteriorly (Figure lA). First three pairs biramous (second pereopod shown in Figure IJ ), last two pairs uniramous and slightly smaller than pairs 1-3. PLEOPODS.— Absent. TELSON (Figure IK).— Not segmented from sixth abdominal somite; slightly emarginate pos- teriorly; bears 1 + 1 densely plumose setae. Fourth pair of setae longest, about one-half width of tel- son. Minute spinules at base of each seta. Larger spinules along terminal margin between bases of four inner pairs and on setae themselves but rarely on seventh pair. Uropods visible and en- closed. No anal spine. STAGE II ZOEA Mean total length of Stage II (Figure 2 A) 7. .5 mm irange 6.7-8.2 mm; 25 specimens). Chromatophore color and pattern essentially identical to Stage I. except chromatophores larger and color more pronounced, especially in mouth parts. Rostrum still without teeth and not curved downward as sometimes in Stage I. Carapace with prominent supraorbital spine and clearly visible antennal and pterygostomian spines. These three 160 HAYNES: DESCEUPTION OF PANDALUS BOREALIS LARVAE spines persist through all remaining zoeal stages Epipodite of first maxilliped slightly larger than in Stage I but still not bilobed; pleurobranchiae present as primordial buds. ANTENNULE (Figure 2B).— Three-segmen- ted; bears large outer and smaller inner flagellum on terminal margin. Flagella not segmented. Inner flagellum conical, bears one long spine ter- minally. Outer flagellum bears two groups of aes- thetascs: one group terminally consisting of eight aesthetascs, two of them larger than remaining six, and a pair of aesthetascs on inner margin. A small budlike projection (not shown in Figure 2Bi 0.25 mm Figure 2. — Stage II zoea ofPandalus borealis A, whole animal right side; B, antennule. ventral; C. antenna, ventral; D, mandibles (left and right), posterior; E. maxillule. ventral: F, maxilla (exopodite and endopodite), dorsal. 161 FISHERY BULLETIN: VOL. 77, NO. 1 0. 5 mm Figure 2. — Stage II zoea ofPandalus borealis: G, first pereopod, lateral; H, second pereopod, lateral; I. third pereopod. lateral; J, fourth pereopod, lateral; K, fifth pereopod, lateral; L, telson, dorsal. originates at base of flagella and bears five simple setae. Proximal segment of antennule usually bears five setae laterally near slightly expanded base, three plumose setae laterally and distally, about nine dorsally curving but smaller plumose setae around distal joint, and large spine project- ing slightly downward from ventral surface. Second segment bears two plumose setae later- ally and about six dorsally curving plumose setae around distal joint. Third segment bears seven plumose setae laterally, about four of them originating ventrally, and three simple setae laterally at base of outer fla- gellum. 162 HAYNES DESCRIPTION OF PANDALUS BOREALIS LARVAP; ANTENNA (Figure 2C).— Flagellum two- segmented, still shorter than scale, styliform, and tipped by two small simple setae and short spine. Antennal scale fringed with 25 or 26 long, thin, plumose setae along terminal and inner margins; still has six joints distally but only the three most distal joints complete. Protopodite bears minute spine at base of scale in addition to conspicuous spine at base of flagellum. MANDIBLES (Figure 2Dl.— More massive than in Stage I. Incisor processes of both mandi- bles bear additional tooth. Both mandibles bear additional denticles and molar processes more de- veloped. Lacinia mobilis of left mandible consists of single spinous denticle. Curved lip of trun- cated end of molar process of right mandible more developed than in Stage I. MAXILLULE (Figure 2E).— Coxopodite bears 12-15 spines and row of fine hairs proximally; spinules on two of the terminal spines of coxopo- dite resemble a row of teeth. Basipodite and en- dopodite essentially unchanged from Stage I, ex- cept basipodite bears two additional spinulose spines. MAXILLA (Figure 2F, exopodite and endopodite). — Exopodite similar in shape to Stage I except more distinctly expanded proximally; bears 17-19 marginal plumose setae in addition to plumose seta at proximal end. Endopodite un- changed from Stage I. Coxopodite bears 3 setae on distal lobe and 17-19 on proximal lobe. Each lobe of basipodite bears additional seta. MAXILLIPEDS.— Essentially identical to Stage I but bear additional setae as follows. On first maxilliped, protopodite bears 8-10 setae on proximal segment and 19-21 on distal segment; endopodite bears 4, rarely 5, setae on proximal segment; exopodite bears 7 or 8 natatory setae rather than 5 or 6 as in Stage I; no change in epipodite. On second maxilliped, protopodite bears seta on proximal segment and 8-10 setae on distal segment; exopodite bears 14 lateral natatory setae in addition to the 2 terminal setae. On third maxil- liped, endopodite bears additional seta terminally on dactylopodite, 2 additional setae on propodite, and additional seta on carpopodite, setation for- mula 5, 7, 3, 1, 2; exopodite bears 16 lateral nata- tory setae in addition to 2 terminal setae. No gill buds on second or third maxillipeds. FIRST PEREOPOD (Figure 2G).— Protopodite bears three setae. Endopodite functionally de- veloped; five-segmented, terminating in simple conical dactylopodite; setation formula 5, 3, 2. 2, 2. Exopodite, longest among pereopods, bears 2 ter- minal and 14 lateral natatory setae. SECOND PEREOPOD (Figure 2H),— Protopodite bears two setae. Endopodite similar to first pereopod except shorter; setation formula 4, 3, 1, 1, 2. Exopodite bears 2 terminal and 13 or 14 lateral natatory setae. THIRD PEREOPOD (Figure 21).— Protopodite bears two setae. Endopodite one-fourth to one- third longer than exopodite; dactylopodite slightly longer than in first two pereopods; setation for- mula 3, 4, 2, 1, 2. Exopodite noticeably shorter than exopodites of first and second pereopods and bears 2 terminal and 9 or 10 lateral natatory setae. FOURTH PEREOPOD (Figure 2J).— Endopodite five-segmented but still poorly de- veloped and directed under body somewhat an- teriorly as in Stage I (Figure 2A); dactylopodite and propodite bear two setae and three setae, re- spectively. No exopodite. FIFTH PEREOPOD (Figure 2K).— Similar to fourth pereopod but shorter and dactylopodite tipped with single seta. No exopodite. PLEOPODS (Figure 2A).— Present as distinct buds. TELSON (Figure 2L).— Similar in shape to Stage I but distinctly jointed from sixth abdominal somite; bears 8 4-8 densely plumose setae. Uropods still enclosed. Anal spine present but mi- nute. STAGE III ZOEA Mean total length of Stage III 9.5 mm (range 9.0-10.0 mm; 10 specimens). From this stage on, zoeae gradually become more orange and color pattern not useful in identifying a given stage. Rostrum (Figure 3A) projects horizontally but curves slightly downward at tip; bears one or two teeth at base. Epipodite of first maxilliped bilobed; pleurobranchiae present as small buds. ANTENNULE (Figure 3B, inner and outer 163 FISHERY BULLETIN: VOL, 77, NO 1 flagella). — Flagella not segmented. Inner flagel- lum about one-half length of outer flagellum, bear- ing stiff seta at base of terminal spine. Outer flagellum bears four long and two shorter aes- thetascs terminally and two groups of three aes- thetascs each proximally. ANTENNA (Figure 3C).— Flagellum eight- segmented, about equal in length to scale, tipped by three short setae and remnant of terminal spine. Antennal scale narrower than in Stage II and fringed with about 30 plumose setae; two complete joints at tip. Spine on protopodite at base of scale considerably larger than in Stage II. MAXILLIPEDS.— Change in form and setation of maxillipeds from Stage III on is slight and con- sists primarily of second maxilliped becoming 0. 5 mm 0. 5 mm 164 HAYNES: DESCRIPTION OF PANDALUS BOREALIS LARVAE curved as in adult and its propodite slightly vi-id- ened, third maxilliped becoming shaped as in adult, and natatory setae on exopodites of second and third maxillipeds increasing in number to usually 20 in Stage V. FIRST PEREOPOD ( Figure 3D ).— Has begun to acquire adult shape, particularly in widened pro- podite and carpopodite segments. SECOND PEREOPOD (Figure 3E i.— Similar to Stage II except distal joint of propodite projects slightly anteriorly. THIRD, FOURTH (Figure 3F), AND FIFTH PEREOPODS.— Endopodites similar; like first pereopod have begun to acquire adult shape, espe- cially in lengthened dactylopodite and widened propodite. Ischiopodite articulates somewhat lat- erally with meropodite. PLEOPODS (Figure 3G, second pleopod).— Bilobed, unsegmented. and without setae. TELSON (Figure 3H).— Endopodite not fully developed; about one-third length of exopodite and bearing several setae along lateral and posterior margms. Uropods free. Anal spine clearly visible. 0. 5 mm Figure 3. — Stage III zoea of Pandal us borealis: A, whole ammal, right side; B. antennule i inner and outer flagella). ventral; C, antenna, ventral; D. first pereopod. lateral. E. second pereopod, lateral; F. fourth pereopod, lateral; G. second abdominal somite and pleopod, right side; H, telson, dorsal. 165 FISHEKY BULLETIN: VOL 77. NO. 1 STAGE IV ZOEA Mean total length of Stage IV 13.0 mm (range 12.6-13.2 mm; 10 specimens). Rostrum (Figure 4A) bears four to eight but usually six teeth dor- sally, no teeth ventrally; tip not bifid. No change in epipodite of first maxiliiped or pleurobranchiae except slight increase in size. Epipodite on second maxiliiped present as small bud. No mastigobran- chiae. ANTENNULE (Figure 4B, inner and outer 0. 5 mm 0. 5 mm 0. 5 mm 0. 5 mm FK;l;ke 4. — Stage IV zoea nf Pandalus bumaUs: A, rostrum, right side; B. antennule (inner and outer flagella), ventral; C. antenna, ventral; D, first pereopod i distal segments only), lateral; E, second pereopod (distal segments only), lateral; F, second abdominal somite and pleopod, nght side; G, telson. dorsal. 166 HAYNES DESCRIPTION OF PA.VD.AZ.C.S BOREALIS LARVAE flagellai. — Flagella two-segmented. Inner flagel- lum nearly as long as outer flagellum. Outer flagellum bears four aesthetascs and two spines terminally and three groups of three aesthetascs each on proximal segment. ANTENNA (Figure 4C ). — Flagellum 15- segmented; 1.5-2 times length of scale, extending past tips of plumose setae fringing antennal scale. Antennal scale without joints at tip. Other than increase in size, changes in antennal scale from Stage IV onward are negligible. FIRST PEREOPOD (Figure 4D).— Distal joint of propodite projected anteriorly and tipped with small spine. SECOND PEREOPOD (Figure 4E).— Distal joint of propodite projected anteriorly to about one-half length of dactylopodite; projection tipped by two spines, one terminal and other subterminal and much shorter. Dactylopodite bears one termi- nal spine and two considerably shorter subtermi- nal spines. PLEOPODS (Figure 4F, second pleopod).— Segmented; length of second pair of pleopods about one-half height of second abdominal somite. Exopodite usually bears one to four small setae terminally and endopodite sometimes bears single seta terminally. Appendices internae not present. TELSON (Figure 4Gi.— Endopodite of uropod about two-thirds length of exopodite and fringed with about 20 setae. Lateral margins of telson nearly parallel but slightly divergent posteriorly and bear two spines each. Posterior margin still slightly emarginate; bears 6 -(- 6 spines, the out- ermost (sixth) pair usually without spinules. STAGE V ZOEA Mean total length of Stage V 16.0 mm (range 15.2-17.1 mm; 10 specimens). Rostrum (Figure 5A) with 9-12 dorsal teeth, bifid tip, and usually 4. but sometimes 5, partially developed ventral teeth. Pleurobranchiae curve somewhat anteriorly and edges minutely lobulate. Mastigobranchiae occur as minute buds on protopodite of third maxilliped and pereopods 1-4. ANTENNULE (Figure 5B, flagella only).— Inner flagellum four-segmented. Outer flagellum four- or five-segmented; bears six groups of three aesthetascs each. Each segment bears at least one seta but number and location of setae somewhat variable. ANTENNA (Figure 5C).— Flagellum 2-3 times length of scale. FIRST PEREOPOD (Figure 5D, distal segments only). — Projection of propodite at least one-half length of dactylopodite; bears two small spines, one terminally and one subterminally. Dactylopo- dite bears small spine subterminally in addition to terminal spine. SECOND PEREOPOD (Figure 5E, distal seg- ments onlyl. — Chela well formed. Terminal spine of propodite shorter and stouter than in Stage IV. Dactylopodite bears five spines, the distal two especially stout. Carpopodite usually at least par- tially segmented. PLEOPODS (Figure 5F, second pleopod).— Second pair of pleopods about equal in length to height of second abdominal somite; outer flagel- lum fringed with 11 or 12 plumose setae, inner flagellum with about 8 setae. Appendices internae usually present on pleopods 2-5; tips sometimes bear a few cincinnuli. TELSON (Figure 5G). — Lateral margins of tel- son essentially parallel and bear two spines each. Posterior margin straight or slightly emarginate, bearing 6 + 6 spines. Uropods similar in shape to adult; no evidence of transverse hinge of exopo- dite. STAGE VI (MEGALOPA) Mean total length of Stage VI 18.5 mm (range 17.4-20.2 mm, 5 specimens). Rostrum (Figure 6A) shaped as in adult; bears 13-15 dorsal teeth in addition to distinct bifid tip, and 6 or 7 distinct ventral teeth. Usually one or two setae between dorsal teeth. Carapace lacks supraorbital spine. Exopodites on maxillipeds and pereopods 1-3 re- duced. Pleurobranchiae and mastigobranchiae shaped as in adult. Inner and outer flagella of antennule eight- to nine-segmented and five- segmented, respectively. Flagellum of antenna about 6 times length of antennal scale. Mandibles still without palps. Chaelae of first and second pereopods shaped as in adult; carpal joints of left 167 FISHERY BULLETIN: VOL 77. NO 1 0. 5 mm Figure 5. — Stage V zoea of Pandal us borealis: A, rostrum, right side; B.antennulelflagellaonlyl, ventral; C, antenna, ventral; D, first pereopod (distal segments only), dorsal; E, second pereopod idistal segments onlyi, dorsal; F. second abdominal somite and pleopod. right side; G. telson, dorsal. and right second pereopods 20-25 and 10-13, re- spectively. Pleopodal setae extend along entire lateral margins of both flagella; tips of appendices internae bear several distinct cineinnuli. Length of second pair of pereopods, excluding setae, 1.5-2 times height of second abdominal segment. Telson (Figure 6B) shows, for first time, shape and spina- 168 tion similar to adult; lateral margins converge posteriorly but widen slightly at junction with posterior margin; typically four spines on each lateral margin but in this stage and Stages VII and VIII one lateral spine often lacking. Posterior margin of telson rounded but not as much as in Stage VII; bears 3 + 3 stout spines and sometimes HAYNES DESCRIPTION OF PA.WDALUS BOREALIS LARVAE u J . 5 mm Figure 6. — Stage VI imegalopal of Pandalus bnrealis: A. ros- trum, right side; B. t«lson. dorsal. remnants of a spine or two from Stage V. Trans- verse hinge of exopodite of uropod complete. STAGES VII AND VIII (JUVENILES) Mean total length of Stage VII (first juvenile) 18.4 mm (range 15.1-21.0 mm; 5 specimens). Usu- ally two setae between most rostral teeth. Carapace without supraorbital spine. Arthro- branchiae on third maxilliped and pereopods 1-4 present as minute buds. Mandibular palp present for first time; three-segmented. Inner and outer flagella of antennule each 11- to 13-segmented. Exopodites on maxillipeds and pereopods 1-3 rem- nant. Third abdominal somite sometimes bears minute spine on middorsal posterior margin. Car- pal joints of left and right second pereopods 28-30 and 14-17, respectively. Lateral margins of telson (Figure 7) typically bear 5 + 5 spines; posterior margin rounded as in adult. Mean total length of Stage VIII (second juvenile) 21.6 mm (range 19.0-23.6 mm; 8 speci- mens). Morphological differences between Stages VII and VIII slight. Most notable features of Stage VIII: at least three or four setae between most rostral spines; complete lack of exopodites on third maxilliped and pereopods 1-3; inner and outer flagella of antennule each 15- to 16-segmented; lateral margins of telson typically bear 6 + 6 spines. COMPARISON OF LARVAL STAGES WITH DESCRIPTIONS BY OTHER AUTHORS The first description of larvae ascribed to Pan- daliis horealiti was given by Sars ( 1900), based on specimens collected from plankton. Berkeley (1931) showed that Sars' larvae could not be P. borealis; almost simultaneously Lebour (1930) showed that they were Caridion gordoni (Bate). Sars' "post-larval" specimen, however, is consid- ered by both Lebour and Berkeley to be correctly identified as P. borealis . As far as can be compared, my Stage VI (megalopa) and Sars' "post-larval" specimen are essentially identical except for the I' n \ L J 0. 5 mm Figure 7.— Stage VII (first juvenilel of Pandalus borealis: tel- son, dorsal. 169 FISHERY BULLETIN; VOL rostral tip, which in my larva is bifid but in Sars' is styliform, and the chela of the first pereopod, which is completely developed in my larva but not in Sars'. Stephensen ( 1912) described zoeal Stages I to V from plankton that he provisionally identified as "P. propinquus (?)" and Stage III zoeae (1916) as "Spirontocaris-\ar\a No. 4." Berkeley (1931) not- ed the close similarity of the "P. propinquus (?)" specimens to zoeae of P. borealis from British Co- lumbia waters. Stephensen (1935) later decided that both "P. propinquus (?)" and "Spirontocaris- larva No. 4" were actually zoeae of P. borealis. He also compared his zoeae with fragments of a specimen identified by Kr0yer as Dymas typus and decided Kr0yer's specimen was a Stage IV zoea of P. borealis. Comparing the description and figures of Stephensen's ( 1912) zoeae and mine in general for each stage, my zoeae are slightly more advanced than Stephensen's. In my Stage I zoeae the anten- nal scale bears 19 plumose setae; the basipodite and coxopodite of the maxillule bear 9 + 1 and 9 spines, respectively; the endopodite of the first maxilliped is segmented; and the exopodites of maxillipeds 1, 2, and 3 bear 6. 14, and 16 natatory setae, respectively. In Stephensen's Stage I zoeae the antennal scale bears only eight or nine plumose setae; the basipodite and coxopodite of the maxillule bear five and six spines, respec- tively; the endopodite of the first maxilliped is not segmented; and the exopodites of maxillipeds 1, 2, and 3 bear 4, 10, and 10 natatory setae, respec- tively. In Stage II, the relative difference in number of setae and spines between my zoeae and Stephensen's remains essentially the same, except in my zoeae the exopodites of pereopods 1, 2, and 3 bear 16, 16, and 12 setae, respectively, whereas in Stephensen's zoeae they each bear 18 setae. In Stage III, the rostrum of my zoeae bears only a single tooth and the antennal flagellum is eight- jointed, but in Stephensen's zoeae the rostrum bears as many as three teeth and the antennal flagellum is notjointed. In Stage IV, the rostrum of my zoeae bears six or seven teeth, the antennal flagellum is 15-segmented, and the telson bears eight pairs of spines whereas in Stephensen's zoeae the rostrum bears only four teeth, the an- tennal flagellum is still unsegmented, and the tel- son bears only seven pairs of spines. In Stage V, the most obvious difference is that the pleopods are segmented in my zoeae but not in Stephen- sen's. In his 1916 report, Stephensen described an ad- ditional larva which he considered the sixth stage oi P. propinquus G. O. Sars; later (1935) he decided it was P. borealis. According to Stephensen, this stage closely resembles his Stage V zoeae, differ- ing primarily in the left second pereopod being con- siderably longer than the right, and, for both sec- ond pereopods, the joint at the distal end of the carpopodite being complete. In my larvae, mor- phological change from Stage V to Stage VI is sufficiently pronounced that I consider the sixth stage to be the megalopa. If Stephensen was cor- rect in assuming his specimen to be a sixth stage zoea, then P. borealis in Greenland waters has at least six zoeal stages compared with only five zoeal stages in Alaska waters. In her classic study of pandalid larvae from British Columbia waters, Berkeley (1931) de- scribed and figured P. borealis Stage I zoeae reared in the laboratory and Stages II-VI collected from plankton. Her larvae follow a pattern of develop- ment similar to my larvae but each stage is less well developed. For instance, she described the antennal flagellum in her Stage I zoeae as tipped by a simple seta whereas in my zoeae it is tipped by a spinulose spine, and she neither figured nor de- scribed the spinous seta which my zoeae bear on the protopodite at the base of the flagellum. Also, the exopodite of the maxilla of her Stage I zoeae bears 8-10 long simple setae and has no trace of a proximal expansion whereas in my zoeae the exopodite of the maxilla bears 11 long plumose setae as well as one longer, thicker seta at the proximal end which is slightly expanded. In Stage II, the outer flagellum of the antennule of Berke- ley's zoeae is figured as bearing only three aes- thetascs distally whereas my zoeae bear eight. The proximal expansion of the exopodite of the maxilla is "just appearing" in Berkeley's Stage II but in mine it is distinctly expanded. Moreover, she de- scribed the telson as being still indistinctly seg- mented from the sixth abdominal somite but in my zoeae it is always distinctly segmented at Stage II. Berkeley's Stage III zoeae are essentially identical to mine as far as can be determined from her de- scription. Her Stage IV zoeae have four small teeth at the base of the rostrum, the pleopods are without joints, and there is no epipodite on the second maxilliped. In my Stage IV zoeae, the ros- trum usually has six teeth, the pleopods are jointed, and an epipodite occurs on the second maxilliped. In Stage V, the rostral tip of Berke- ley's zoeae is still styliform. There is no evidence 170 HAYNES: DESCRIPTION OF PANDALUS BOREALIS LARVAE from either her description or figure of ventral teeth on the rostrum, and the pleopods have not yet developed appendices internae. In my Stage V zoeae the rostral tip always bears at least a pro- tuberance indicative of the bifid tooth, and pleopods 2-5 bear at least partially developed ap- pendices internae. In contrast to my Stage VI, the megalopa, Berkeley's Stage VI is still typically zoeal: there is still no mention of ventral rostral teeth, the carapace still bears a supraorbital spine, the carpopodites of the second pereopods are not segmented, and the telson bears three pairs of lateral spines (not including the sixth terminal pair) and terminal setal pairs 2-4 have begun to degenerate. Berkeley (1931) also mentioned a P. borealis larva she obtained from plankton that, according to her. corresponds to the sixth stage of P. danae Stimpson and is similar to that described by Sars (1900) as the "post-larval" stage of P. borealis. Berkeley's sixth stage and Sars' "post-larval" stage are typically nonzoeal as indicated by the lack of supraorbital spines, segmentation of the carpopodites of the second pereopods, degenera- tion of the pereopodal and third maxilliped exopo- dites, and the typically adult shape and spination of the telson. Because this stage would be at least the seventh stage, it appears that P. borealis in British Columbia waters, as well as Greenland waters (Stephensen 1916), has at least six zoeal stages compared with only five zoeal stages in Alaska waters. The preceding comparisons show that Berke- ley's zoeae were less well developed at each given stage than mine and an additional stage or two was probably necessary for her zoeae to reach the megalopa stage. An apparent contradiction to this delayed development is the lack of segmentation of the antennal scale in the early stages of Berke- ley's zoeae. As shown by Haynes (1976), however, Berkeley was mistaken in this regard and her specimens undoubtedly possessed a segmented scale in the early stages. The only other description of larvae of P. borealis known to me is that of Kurata ( 1964) who, like Berkeley 1 1931 ), obtained Stage I zoeae in the laboratory from known parentage but Stages II-VII from plankton. Kurata's zoeae are essen- tially identical to mine through Stage V, except the rostrum of Kurata's Stage V zoeae is iden- tical to the rostrum of my Stage IV zoeae. Kurata's Stage VI corresponds to my Stage V, but his Stage VII possesses characteristics intermediate be- tween my Stages V and VI. For instance, in Kura- ta's Stage VII the exopodites on pereopods 1-3 and the third maxilliped have not begun to degenerate nor are the carpopodites segmented whereas in my Stage VI (megalopa) the exopodites on pereopods 1-3 and the third maxilliped are reduced and the carpopodites of the left and right second pereopods are segmented. Also, the lateral spination and shape of the telson of Kurata's Stage VII are typi- cal of postzoeae but posteriorly the telson bears 6 + 6 spines, a typically zoeal characteristic. By studying Stage VII individuals just prior to molt- ing, Kurata found that Stage VIII individuals pos- sessed a distinct mandibular palp and degenera- tion of posterior telson spines 2-4. He concluded that Stage VII was the last zoeal stage and Stage VIII the first postzoea, or megalopa. According to Lebour (1930). the lack of an outer seta on the maxillule in zoeae of Pandalus is one criterion for distinguishing this genus from cer- tain other Caridea. Pike and Williamson (1964), however, found the seta consistently present in early stages of British species of Pandalus. Oc- currence of the seta in Stage I zoeae has been reported by Gurney ( 1942) for Pandalus montagui Leach and P. stenolepis Rathbun; by Kurata (1955, 1964) for P. borealis and P. kesslen Czer- niavski; and Modin and Cox ( 1967) for P.jordani Rathbun. I have consistently found the seta in the early stages of P. hypsinotus, P. goniurus, and P. borealis. Lebour's suggestion that the lack of the seta is a distinguishing criterion for zoeae of Pan- dalus should, therefore, be disregarded. In addition to P. borealis. larvae have been de- scribed, at least in part, for nine other species of pandalids from the North Pacific Ocean: P. goniurus, P. jordani, P. platyceros Brandt, P. danae, P. kessleri, P. hypsinotus, P. stenolepis, Pandalopsis dispar Rathbun, and P. coccinata Urita. Of these nine species, larvae of Pandalus stenolepis, P. jordani. and P. goniurus are most like larvae of P. borealis, being characterized by exopodites on pereopods 1-3 rather than only on pereopods 1 and 2 and by poorly developed pereopods in Stage I. Zoeae of P. stenolepis were described by Needier ( 1938). Based on her descrip- tions, zoeae of P. stenolepis are readily distin- guished from zoeae of P. borealis by 1) the shape and spination of the rostrum, which in Stage I P. stenolepis is about as long as the carapace and projects upward rather than downward as in P. borealis, and 2) the fringed posterior edge of the abdominal somites and the serrated margins of 17] FISHERY BULLETIN VOL 77. NO. 1 the carapace, both of which persist to Stage V in P. stenolepis but never occur in P. borealis. Larvae of P. jordani have been described from specimens reared in the laboratory. Compared with development of similar species, Modin and Cox (1967) and Lee (1969) obtained more stages (11-13 and at least 8, respectively) than expected for larvae of P.jordani from plankton. Because of the possibility of these extra stages, only Stage I zoeae of P. borealis and P. jordani can be com- pared. Upon hatching, zoeae of P. borealis are slightly more developed than zoeae of P. jordani. For instance, in Stage I P. jordani, the exopodites of maxillipeds 1,2, and 3 bear 4, 9-11, and 11 or 12 natatory setae, respectively; the left mandible bears no lacinia mobilis; the basipodite of the maxillule bears six spines terminally; and the scaphognathite of the maxilla bears seven to nine setae along its outer margin. In Stage! P. borealis, maxillipeds 1, 2. and 3 bear 5 or 6, 13 or 14, and 16 natatory setae, respectively; the left mandible bears a single lacinia mobilis; the basipodite of the maxillule bears 9 spines terminally; and the scaphognathite of the maxilla bears 12 setae along its outer margin. Beyond Stage I, the most distin- guishing difference between zoeae of P. jordani and P. borealis seems to be the development of the rostral tip which in zoeae of P. jordani remains acuminate but in zoeae of P. borealis becomes bifid in later stages. In an earlier report (Haynes 1978), I described larvae of P. goniurus reared in the same manner as larvae of P. borealis described here. Larvae of both species are morphologically similar, espe- cially in early stages, and often occur together in plankton. To facilitate identification of larvae of these two species, the most readily observable morphological differences are listed by stage in Table 1. Larvae of P. goniurus are characteristi- cally smaller than those of P. borealis and in Table i.- -Morphological characteristics for distinguishing between larvae of Pandalus borealis and P. goniurus reared in situ in Kachemak Bav. Alaska. Stage and characteristic P borealis P goniurus Stage I zoea Mean total length (mm) No of plumose setae tnnging antennal scale No ot spines terminally on basipodite of maxillule No ot plumose setae on scapliognathite (in addition to single proximal seta) No of nalaory setae on exopodites fVlaxillipeds 1, 2, 3, Stage II zoea Mean total length (mm) No of plumose setae fringing antennal scale No of natatory setae on exopodites: Maxillipeds 1. 2. 3. Pereopods 1. 2. 3. Stage III zoea Mean total length (mm) Rostrum Antennal flagellum Antennal scale Stage IV zoea Mean total length (mm) Rostrum Antennal flagellum Propodite of pereopod 2 Pleopods Stage V zoea Mean total length (mm) Rostrum Chela ot pereopod 2 Pleopods Stage VI (megalopa) Mean total length (mm) Rostrum 6 7 (range 6 5-7 3, 25 specimens) 19 5-6. 13-14, 16 7 5 (range 6 7-8 2, 25 Specimens) About 25 7, 16, 18 16, 16, 12 9 5 (range 9 0-100, 10 specimens) 1-2 conspicuous teeth 8- segmented About 30 setae 13 (range 12 6-13 2; 10 specimens) 6-7 dorsal teeth About 1'? scale, extending past tips of plumose setae Projected antenorly about '2 length of dactylopodite Segmented, pleopod 2 about '; height ol abdominal somite 16 (range 15 2-17 i. 10 specimens) 9-12 dorsal teeth, tip bifid. 4-5 partially developed ventral teeth Fully formed With appendices internae, fringed with plumose setae, pleopod 2 as long or longer than height of abdominal somite 18 5 (range 17 4-20.2, 5 specimens) 13-15 dorsal teeth. 6-7 ventral teeth 4 (range 3 7-4 2, 9 10 specimens) 5 9 {range 4 5-5 3. 10 specimens) About 19 6, 12. 14 12, 8. 8 6 2 (range 6 0-6 6, 10 specimens) 1 inconspicuous tooth 3- segmented About 20 setae 7 7 (range 6 8-8 3. 10 specimens) 2 dorsal teeth Longer than scale but not extending past tips ol plumose setae Projected antenorly only slightly Unsegmented, pleopod 2 about ^ a height of abdominal somite 10 3 (range 8 2- 11 .3: 10 specimens) 5-6 dorsal teeth; tip not bifid (but may show slight protuberance), no ventral teeth Not fully formed, propodite extension about ^ 2 length of dactylopodite Without appendices internae; 2-4 simple setae terminally, pleopod 2 about 2 3 height of abdominal somite 138 (range 11 1-15 8, 6 specimens) 8-9 dorsal teeth. 4-5 ventral teeth 172 HAYNES DESCRIPTION OF PAXriALIS RI}RKALIS LAKVAE Stages I-III the number of setae on certain appen- dages, particularly the antennal scale and certain mouthparts, is fewer than for zoeae of P. borealis. From Stage IV to megalopa, the rostrum of P. borealis has more dorsal teeth, the second pereopods are more developed, and the pleopods are fringed with more setae than for larvae of P. goniurus. LITERATURE CITED Berkeley, a. a. 1931. The post-embryonic development of the common pandalids of British Columbia Contnb- Can Biol 6(61:79-163. GURNEY, R. 1942. Larvae of decapod Crustacea. Ray Soc. (Lond.i Publ. 129. 306 p. Haynes, E. 1976. Description of zoeae of coonstripeshrimp. Pantfa/us hypsinotus. reared in the laboratory. Fish Bull.. U.S. 74:323-342. 1978. Description of larvae of the humpy shrimp. Pan- dalus goniurus. reared in situ in Kachemak Bay. Alas- ka. Fish. Bull.. U.S. 76:235-248. KL'RATA. H. 1955. The post-embryonic development of the prawn, Pandalus kesslert. Bull. Hokkaido Reg. Fish. Res. Lab. 12:1-15. 1964. Larvae of decapod Crustacea of Hokkaido. 3. Pan- dalidae. Bull. Hokkaido Reg. Fish. Res. Lab. 28:23-34. (Transl.. Fish Res. Board Can., 1966. Transl. 693.) LEBOL'R. M. V 1930. The larval stages of Canrfion. with a description of a new species, C. steveni. Proc. Zool. Sue. Lend. 1930:181- 194. LEE, Y. J. 1969. Larval development of pink shrimp, Pandalus jor- dant Rathbun. reared in laboratory. M. S. Thesis, Univ. Washington. Seattle. 62 p. MiiDIN, J. C. A.\D K. W Cux. 1967- Post-embryonic development of laboratory-reared ocean shrxYiip. Pandalus jordani Rathbun. Crustaceana 13:197-219. Needler. a. B, 1938, The larval development of fan(fa/H.s .s^eno/epis. J Fi.sh. Res. Board Can. 4:88-95. Pike, R. B.. and D. I. Williamson. 1964. The larvae of some species of Pandalidae (Decapo- da). Crustaceana 6:265-284. S.\RS. G. O. 1900. Account of the postembryonal development of Pan- dalus borealis Kreyerwith remarks on the development of other pandali. and description of the adult Pandalus borealis. Rep. Nonv. Fish. Mar. Invest. 1:1-45. STEPHENSEN, K. 1912. Report on the Malacostraca collected by the "Tjalfe"'-Expedition. under the direction of cand. mag. Ad. S- Jensen, especially at W. Greenland. Vidensk. Medd, Dan. Naturhist. Foren Kbh. 64:57-134. 1916- Zoogeographical investigation of certain fjords in southern Greenland, with special reference to Crustacea. Pycnogonida and Echinodermata including a list of Al- cyonaria and Pisces. Medd. Gronl. 53:230-378. 1935. Crustacea Decapoda, The Godthaab Expedition 1928. Medd. Gronl. 80:1-94. 17.3 RELATIONSHIPS OF THE BLUE SHARK, PRIONACE GLAUCA, AND ITS PREY SPECIES NEAR SANTA CATALINA ISLAND, CALIFORNIA' Timothy C. Tricas^ ABSTRACT Small fishes and cephalopods associated with both pelagic and inshore habitats composed the major prey for the blue shark. Prtnnace glauca. near Santa Catalina Island, Calif. The northern anchovy. Engraulis mnrdax, was the predominant prey for sharks in the immediate study area while at least 13 species of pelagic cephalopods constituted major prey for sharks in more distant oceanic waters. Inshore species taken by sharks included pipei\sh.Syngnatbus californiensis: jack mackerel, Trachurus sym- metricus; and blacksmith. Chrornis punctipinnis. In addition, sharks moved inshore to feed on winter .spawning schools of market squid. Loligo opalesci'ns. Digestive rate studies and telemetric monitoring of activity patterns indicate that sharks forage in waters near the surface from around midnight through dawn. Diel activities of prey species were examined and show that most prey dispersed in the upper water column at night and refuged during the day either by schooling (anchovies and jack mackerel ) or by retreating to deeper waters (pelagic cephalopods*. Field observations of shark feeding behavior indicate that predatory modes vary in response to prey behavior. Thehlue shark. Prionace glauca (Carcharhinidaei (Figure 1), is a pelagic carnivore cosmopolitan in tropical and warm temperate seas. Because of its pelagic habits, the majority of ecological studies on this species have been predicated on data from sharks captured by sport and commercial fisheries. As a result data has been largely qual- itative, and the shark's role as a predator in the epipelagic habitat has remained unclear. The importance of small fish as prey items for blue sharks has been described by Couch (1862), Lo Bianco (1909). Bigelow and Schroeder (1948), Strasburg ( 1958 ). LeBrasseur ( 1 964 ), Bane ( 1968 ), Stevens (1973), and others. These prey generally are schooling species common in productive coast- al waters. Cephalopods were also reported as major prey but little information is available on specific identifications (see Stevens 1973: Clarke and Stevens 1974). Although blue sharks have been observed feed- ing on dead or wounded cetaceans (Bigelow and Schroeder 1948; Cousteau and Cousteau 1970) there is little indication that they habitually prey on live, healthy marine mammals. The occurrence 'Based on a portion of a thesis submitted in partial fulfillment of the requirements for the M.A. degree in the Department of Biology. California State University. Long Beach. Calif Con- tribution no. 27 from the Catalina Marine Science Center, Uni- versity of Southern California. ^Department of Biology, California State University, Long Beach, Calif; present address: Department of Zoology, Univer- sity of Hawaii at Manoa, Honolulu, HI 96822. of mammalian tissue in the diet of blue sharks is rare (Strasburg 1958; Stevens 1973), and such feeding is most likely directed to dead mammals or those in poor health. Air/sea disasters have re- sulted in attacks on humans by blue sharks (see Schultz and Malin 1963; Fitch^) but these cases usually involved injured persons or corpses. Standard tagging programs (Weeks 1974; Casey 1976; Stevens 1976) and telemetric trackings (Sciarrotta and Nelson 1977) have provided some information on large-scale movements of blue sharks but relatively little is known of their orien- tation mechanisms and predatory behavior. Despite the profusion of descriptive reports, there still exists a great need for quantitative data on ecological relationships between the blue shark and its prey species. With these ideas in mind, I undertook this study within a limited geographic area to 1 ) provide a quantitative assessment of the diet of blue sharks near Catalina Island, 2) estab- lish temporal and/or geographical shifts in food habits, and 3) describe behavioral interactions be- tween the blue shark and its prey species. METHODS The study area was located north of the Isthmus, Santa Catalina Island, Calif. (Figure 2). Beds of Manuscript accepted Julv 1978. FISHERY BULLETIN: VOL. 77. NO. 1, 1979. ^J. E. Fitch, California Department of Fish and Game, Opera- tions Research Branch, 350 Golden Shore, Long Beach, CA 90802, pers. commun. May 1976. 175 FISHERY BULLETIN VOL 77. NO 1 FU'.LRK I. — Female blue shark near the ocean surface. FKiL'RE 2.— Study area at Catalina Island, Calif. Hatching indi- cates sampling regions. Sharks feeding among squid schools were observed at x . giant kelp, Macrocystis pynfera, composed the major habitat alongthe island shore. A submarine shelf, averaging 150 m deep, extends approxi- mately 2 km seaward then slopes to depths near 900 m and forms the floor of the San Pedro Basin. "Inshore" sampling stations were located above the shelf within 3 km of the island, and "offshore" stations centered approximately 6 km north of the Isthmus, over deeper basin waters. Sharks were collected monthly between March 1975 and March 1976. Samples were taken during morning and afternoon hours at both inshore and offshore areas with an attempt to maintain a con- sistent area-time sampling schedule. Sharks were attracted to a drifting 7-m work boat by baiting with slashed Pacific mackere\,Sc(>')ihcr japonicus, suspended in a wire basket 5 m beneath the sur- face. Once attracted, sharks were captured by hook and hand line using mackerel or market squid, Lolign npalesvens, as bait. Sharks were landed as quickly as possible to minimize regurgi- tation and then measured, sexed, and inspected for mating scars and general health. Contents of esophagi and stomachs were filtered through 1-mm mesh netting and preserved. Recognizable prey items and their digestive states were re- corded on site. Intestinal tracts were occasionally examined but contributed little information on the diet because of the small pylorus which re- stricted passage of identifiable prey fragments. Except for the market squid, cephalopods in the diet were represented exclusively by beaks. Beaks were paired into sets of upper and lower halves, and identified when possible according to Clarke (19621 andPinkasetal. (1971 1. Specific identifica- tions were verified by comparisons with beaks from collections of local species. Whole volumes of squid were estimated from beak-size/body-weight regressions for the major cephalopod families given by Clarke ( 1962). For calculations, the den- sity of cephalopod flesh was assumed to be 1 g/cm^. A regre.ssion foi- the family Ocythoidae ( not given by Clarke) was generated by plotting beak measure- ments and body weights from local specimens on Clarke's Octopodidae and Argonautidae regres- sions and constructing a parallel relationship curve. Beak-size/body-weight regressions for Vampyroteuthis infernalis were obtained from specimens of local collections. Unidentified cephalopods were omitted from the quantification as they represented only a minor portion of the diet (four small, infrequent species in eight stomachs). In order to approximate normal shark feeding times, digestive rates for captive sharks were de- termined and then compared with field data on the 176 TRICAS: BLUE SHARK AND ITS PREY SPECIES digestive states of anchovies recovered from wild sharks. Three healthy, active sharks were accli- mated for 24 h in large seawater holding tanks (14°-16°C) at Marineland of the Pacific, and then fed marked anchovies and mcU'ket squid. Stomach contents were examined at 6, 12, and 24 h after feeding and the digestion rates recorded. Short-term movements of sharks were moni- tored in the fall and winter seasons by telemetric instrumentation similar to those of Ferrel et al. 1 1974 1 and Nelson (1974). Transmitters were applied externally to free-swimming sharks with stainless-steel darts. Effective transmission range was approximately 2 km under good conditions but depended largely upon ambient noise from waves, wind, and biological sources. Some trans- mitters included a depth sensor for a record of vertical movements. Signals were tracked using a tuneable ultrasonic receiver and a staff-mounted directional hydrophone. These trackings supple- ment the spring through fall trackings of Sciar- rotta and Nelson il977i. The feeding behavior of blue sharks among spawning squid was studied in January 1976. Just before sunset, squid schools were detected near the bottom (30-40 m deep) using a recording Fathome- ter'' and the work boat anchored directly above. A 1,500-W light was then suspended over the water. Squid typically converged beneath the light and formed a large surface school at which sharks usu- ally appeared and began to feed. Orientation and feeding responses of sharks to moving prey were documented during baiting ses- sions at offshore stations. In these tests, a dead anchovy, attached to a light fishing line was cast beyond the bait-attracted sharks and then re- trieved back towards the boat. All field observa- tions of shark and prey activities were made from the boat, using scuba and/or by snorkeling. RESULTS Sharks were captured during all months of the 1-yr study. Of the 81 sharks sampled, 9¥( had recognizable food items in their stomachs. The northern anchovy, Engraulis mordax, was the predominant prey item for sharks in the study area while other small fishes occurred at much lower frequencies (Figure 3). Although sharks fed on a wide variety of cephalopods, an analysis of relative importance (Table 1) showed L. opalescens and squid of the genus Histioteuthis as the most common and sub- stantial cephalopod prey. Monthly analysis re- vealed important shifts between these prey items ivngnalhui ealitarniei rioihurui lymmttrtiu Soualui ocanlhioi Chroma punt.iipinfn\ Cypirluiiti culilornicu Loligo opaltitrnt Chitottulhii, caly Onythoirulhii borrt (Xythoe tuheitulalu Octapoiruihii dtkl (ktopui vp Va/nftyrolfulhii mlr MjMigoltultUi (D/iOi Lv^unutid jmphipiiiJ Rtnilla holhhtn PhyllOipodii lotiry i\g^ (Chluruphvul FIGL'RE 3. — Stomach contents of 81 blue sharks sampled during the year. Occurrence = percent of the 81 individuals containing that prey species. Inset gives a summary by broader food categories. Table l. — Annual relative importance of identified cephalopod prey in the diet of blue sharks near Santa Catalina Island. Calif. Impwrtance was estimated as an index of relative importance (//?/) inaccordwithPinkasetal- 1 1971)://?/ = uV +V)F,whereN (numerical percent) is the percent of individuals of that species among all individual cephalopods recovered; V (volumetric per- cent) is the percent volume represented by that species of all cephalopods recovered. andF (frequency) is the percent of indi- vidual shark stomachs containing that prey species. ■*Reference to trade names does not imply endorsement by the National Marine Fisheries Service. NOAA, Rank Species F N V IRI 1 Loligo opalescens 21 706 31 9 2,152 5 2 Hislioteulhis heteropsis 37 11 4 104 806 6 3 Histioleulhis sp 23 5 50 3 124 6 4 Chiroteulhis calyx 148 53 1 4 99 2 5 Thysanoteuthid squid 1 2 2 43 3 52 2 6 Onychoteuthis boreali-iaponicus 86 24 36 51 6 7 Vampyroleuthis mfernalis 4 9 8 22 14 7 8 Octopoteuthis deletron 62 1 8 11 2 9 Dosidicus gigas 1 2 2 5 1 64 10 Ocythoe luberculata 4 9 8 4 59 11 Mastigoteuthis pyrodes 37 6 3 33 12 Octopus sp 49 1 4 2 78 13 Leachia sp 1 2 2 004 3 177 (Table 2). The high index for L. opalescens in January 1976 reflected the squid's extensive winter spawning assemblages in the study area, and similarly is the reason for its high annual rank (Table 1 ). Histioteuthid squid were probably the most significant cephalopod prey for sharks in more oceanic waters away from inshore spawning aggregations of L. opalescens. The low average number of anchovies and histioteuthid squid per stomach and the relatively small coefficients of dispersion for these two prey indicate that sharks obtained them somewhat regularly over a wide area (Table 3). Conversely, the large coefficient for market squid during its spawning season concurs with observations that this prey was taken from large schools during its spawning runs at inshore areas. Digestive rate tests for healthy, captive sharks were in order with digestive states of prey recov- ered from wild sharks. Anchovies removed from captive sharks at 6 h after feeding were easily identified, and showed only preliminary digestion of fins and margins of the opercula. Likewise, whole squid were easily recognized and had only slight signs of external surface decomposition. At 12 h after feeding, digestion of anchovies was characterized by decomposed abdominal walls, moderate scale loss, and some skin deterioration. Digestion of squid was still negligible. At 24 h, anchovies were well digested with only vertebrae, otoliths, and small sections of muscle present. Squid heads were separated from the body and lenses had detached from the optic cups, but beaks were still implanted within the buccal mass. In general, digestive rates were at least twice as fast for anchovies than for squid. Times of normal feeding activity were estimated by comparing the digestive rate data obtained from captive sharks with recognizable anchovies recovered from wild sharks. Anchovies that were FISHERY BULLETIN: VOL. 77. NO. 1 Table 3. — Dispersion of the three major prey species in blue shark stomachs off Santa Catalina Island, Calif. Means for mar- ket squid were computed for squid spawning season (Mar. 1975, Dec. -Jan. 1976) and nonspawning season (Apr. -Nov. 1975, Feb. 1976). Coefficients of dispersion (ratioof variance to mean) indi- cate grouping of prey among stomachs. A coefficient of 1 de- scribes a random distribution. Larger coefficients describe in- creasingly contagious (clumped) distributions of prey among shark stomachs (Sokal and Rohlf 1969). No. of Mean no. Coellicient sharl183 m) was the formation of small (4-15 m thick), near-surface daytime schools (0-54.9 m deep) that dispersed at night into a thin surface scattering layer (Mais 1974 1. Field observations from the present study indicate a similar behavior for an- chovies near Catalina. In offshore waters during the day, anchovies occurred in large, dense, polarized schools near the surface. In the early evening, schools dispersed horizontally into less dense feeding assemblages with individuals spaced approximately 0.5 m apart. Later at night (0100-0400 h) more dispersed groups and solitary individuals were observed on several occasions, indicating a more complete nocturnal dissolution. In spite of the abundance of this prey no sharks examined near Catalina had stomachs distended with anchovies; usually only one or two had been taken per day. Data from the digestion studies indicate that most predation on anchovies oc- curred in predawn hours which correlates with the increased nocturnal activity of telemetered sharks reported by Sciarrotta and Nelson ( 1977). It seems probable then, that the few anchovies taken by each shark was at least partially due to the noc- turnal dispersion of schools in offshore waters, whereby assemblage densities were reduced and anchovies taken individually. The localized variability of anchovy abundance and schooling behavior that existed between areas and seasons pre.sented different feeding oppor- tunities for sharks. For example, blue sharks cap- tured during the day off Newport Beach, Calif, and in commercial anchovy fishing grounds near Los Angeles Harbor (author unpubl. data) con- tained many more anchovies (approximately 10- 20/individual) than did sharks sampled in the Catalina study area. The two former areas feature nearshore submarine escarpments where the size and concentrations of anchovy schools were among the greatest anywhere in southern California (Mais 1974). The present status of the blue shark-anchovy association may be the aftermath of a previously more complex predator-prey web. Southern California commercial fisheries have severely de- pleted Scomber japonicus and Pacific sardine, Sardinopa sagax, populations (MacCall et al. 1976), both natural prey for blue sharks (author unpubl. data). Although such declines in major forage species may have resulted in increased predation on anchovies, the southern California population is apparently in little danger of over- exploitation by commercial fisheries or pelagic fish predators (Pinkas et al. 1971; Mais 1974; MacCall et al. 1976). Fishes associated with inshore habitats were also taken by sharks. Jack mackerel, Trachurus symmetriciix, are widely distributed throughout the Gulf of Alaska (Miller and Lea 1972), and inhabit both inshore and pelagic habitats (Feder et al. 1974). In southern California waters, adults of this species generally aggregate near the bot- tom or under kelp forests at rocky banks and shal- low coastal areas during daylight and venture into deeper waters at night. Only rarely do jack mack- erel form sizeable surface schools in the open sea (Mais 1974). Similarly, smaller jack mackerel (e.g., near 25 cm TL), common at inshore areas of Catalina, swam along the outer edges of kelp beds during the day in closely spaced schools and some- times aggregated within the kelp forest proper. At night jack mackerel occurred in open waters (away from kelp) often interspersed with Scomber japonicus. Larger pelagic individuals might rep- resent a schooling prey source for blue .sharks in open waters, but stomach content data indicate this was not the case near Catalina. Neave and Hanavan (1960) described concurrent expansion of blue shark and jack mackerel ranges in the Gulf of Alaska during the summer, although no data was presented on possible predator-prey interac- tions. Pipefish were the second most frequent fish prey for sharks in this study and a principal prey for blue sharks off Newport Beach (Bane 1968 1, but because of their small biomass must be regarded as a prey species of minor importance. Free- swimming pipefish were observed at the surface in open water (far from surfgrass or kelp beds) at night, among flotsam kelp during daylight, and during daytime scuba dives in kelp forest and 180 TRICAS BLUE SHARK AND ITS PREY SPECIES snri'grass, Phyllospadix torreyi, habitats along the shore of the island. The occurrence of pipefish at the surface in the San Pedro Channel at night and the fact that sharks containing freshly ingested pipefish were captured 2-5 km from the island imply that this prey was most likely taken in wa- ters away from inshore kelp and surfgrass habitats. Freshly ingested blacksmith, Chroniis punctipinnis, were recovered from a shark cap- tured near Ship Rock at noon. At Catalina, this planktivorous damselfish formed midwater feed- ing aggregations at the outer edges of the kelp forest during the day, and at times ranged sea- ward up to 100 m from the nearest kelp. At dusk, blacksmith retreated to the protection of rocks and crevices (see Quast 1968; Hobson 1976). Blue sharks frequented waters near exposed kelp stands at Ship Rock and have been reported chas- ing and feeding on blacksmith during the day (Sciarrotta and Nelson 1977; Given'^). With the exception of Mastlgotcufhis pyrodes, Vampyrott'uthis infernaliti, and nonspawning Loligo opalescens, all of the cephalopod prey species (or their congeners for which data are available) occur near the surface at night through vertical ascent from greater depths or by normal epipelagic distribution (Roper and Young 1975; Tricas 1977). Mastigoteuthis pyrodes (mesopelag- ic) and V. infernalis (bathypelagic) occasionally migrate to the lower limits of the epipelagic zone at night i Roper and Young 1975). In their study of blue shark movements near Catalina, Sciarrotta and Nelson (1977) described evening-twilight shoreward movements of sharks from late March through early June and suggested the change in movement patterns as a response to seasonal increases of inshore spawn- ing squid and decreases in availability of pelagic fishes offshore. Such movements, however, may not be strictly food related. For example, daily inshore-offshore migrations of sharks (late March through early June) would not be synchronous with the cold-water winter peak (December through February) of inshore squid spawning ac- tivity near the Isthmus. Also, some sharks ob- served during this study fed among spawning squid schools throughout the day and therefore did not exhibit the diel inshore-offshore movement ^R. Given, Catalina Marine Science Center, P.O. Bo.x 398, Avalon, CA 90704. pers. commun. July 1977. pattern. Furthermore, sharks fed upon anchovies m offshore waters throughout the year and there is no indication that the availability of anchovies or jack mackerel to blue sharks significantly changed over the course of this study. Detection of prey by sharks is often dependent on the reception of abnormal or unusual stimuli such as low-frequency vibrations of struggling or fleeing fishes (Nelson and Gruber 1963; Nelson and Johnson 1972). In addition, olfaction plays a well-documented role in location of injured, stressed, or bleeding prey (Tester 1963; Hobson 1963). Ultimately, however, vision (Gilbert 1963) and possibly electroreception (Kalmijn 1971) are the principal senses used immediately prior to at- tack. For blue sharks in a normal nocturnal feed- ing mode, it is probable that search images are formed for a general size rather than for a particu- lar species. Pipefish, for example, were relatively small in biomass, but represented a length charac- teristic of other prey species. Similarly, most cephalopods in the diet fell within the common prey size range (e.g., 5-25 cm TL). Bioluminescent trails of darting anchovies and other small fish and squid were frequently seen while snorkeling at night in offshore waters and likewise would be readily visible to sharks. Also, the majority of cephalopod species taken by sharks possessed photophores. Bioluminescence associated with prey movements and light organs may represent significant predatory cues for sharks at night. ACKNOWLEDGMENTS Thanks to D. R. Nelson for his assistance and to R. Given and R. Zimmer of the Catalina Marine Science Center. F. G. Hochberg, Santa Barbara Museum of Natural History, and L. Pinkas, California Department of Fish and Game, pro- vided helpful suggestions and access to their cephalopod collections. J. Goldsmith, Marineland of the Pacific, provided sharks and facilities for the digestion rate studies. Thanks to C. Shoemaker for her help in the field, J. McKibben for his technical assistance, and H. Izuta Tricas for her help in preparation of the manuscript. E. S. Hobson and J. C. Quast constructively criticized the manuscript. Special thanks to F. Banting and C. Best for their contribution that made this work possible. Finan- cial support was granted by the Office of Naval Research through contract N00014-75-C-0204, under project NR- 104-062, for the program of shark research of which this study is a part. 181 FISHERY BULLETIN VOL 77. NO 1 LITERATURE CITED Bane, G. W. 1968. The great blue shark. Cahf. Curr. 1( ll;3-4. BIGELOW. H. B.. .AND W. C. SCHROEDER. 1948. Sharks. In J. Tee- Van. C. M. Breder, S. F. Hilde- brand, A. E. Parr, and W. C. Schroeder leditorsi. Fishes of the western North Atlantic, Part one, p. 59-546. Mem. Sears Found. Mar. Res., Yale Univ. 1. Casey, J. G. 1976. Migrations and abundance of sharks along the At- lantic coast. In W. Seaman, Jr. 'editorl. Sharks and man — a perspective, p. 13-14. Fla. Sea Grant Program, Rep. 10. Clarke. M. R. 1962. The identification of cephalod "beaks" and the rela- tionship between beak size and total body weight. Bull. Br. Mus. (Nat. Hist.), Zool. 8:419-480. Clarke, M. R., and J. D. Stevens. 1974. Cephalods, blue sharks and migration. J. Mar. Biol. Assoc. U.K. 54:949-957. Couch, J. 1862. A history of the fishes of the British Islands. Vol. 1, p 26-36, 41-44. Groombridge and Sons, Lond. COUSTEAU, J.-Y., AND P. COUSTEAU. 1970. The shark: splendid savage of the sea. Doubleday and Co., Garden City, N.Y., 277 p. Feder, H. M., C. H. Turner, .\nd C. Limbaui-.h. 1974. Obser\'ations on fishes associated with kelp beds in southern California. Calif Dep. Fish Game, Fish Bull. 160, 144 p. Ferrel, D. W., D. R. Nelson, T. C. sciarrotta, e. a. stan DORA, and H. C. Carter. 1974. A multichannel ultrasonic biotelemetry system for monitoring marine animal behavior at sea. ISA (In- strum. Soc. Am.) Trans, 13:120-131. Gilbert, p. W. 1963. The visual apparatus of sharks. In P. W, Gilbert (editor). Sharks and survival, p. 283-326. D. C. Heath and Co., Boston. HOBSON, E. S. 1963. Feeding behavior in three species of .sharks. Pac. Sci. 17:171-194. HoBsoN, E. S., AND J. R. Chess. 1976. Trophic interactions among fishes and zooplankters near shore at Santa Catalina Island, California. Fish. Bull.. U.S. 74:567-598. KALMI.JN, A. J. 1971. The electric sense of sharks and rays. J. Exp. Biol. 55:371-383. LEBRA.SSEUR. R. J. 1964. Stomach contents of blue shark [Prionace glaiica L.) taken in the Gulf of Alaska. J. Fish. Res. Board Can. 21:861-862. Lo Bianco, S. 1909. Notizie biologiche riguardanti specialmente il periodo di maturita sessuale degli animaJi del golfo di Napoh. Mitt. Zool. Stn. Neapel 19:666-667 MACCAI.I., a. D., G. D. STAL:FFER, AND J. -P. TROADEC. 1976 Southern California recreational and commercial marine fisheries. .Mar. Fish. Rev. 38i 1 ):l-32. M,MS, K. F. 1974. Pelagic fish surveys in the California cur- rent. Calif. Dep. Fish Game, Fish Bull. 162, 79 p. MILLER, D. J., AND R. N. LEA. 1972. Guide to the coastal marine fishes of California. Calif. Dep. Fish Game. Fish Bull. 157, 235 p. Neave, F., and M. G. H.-\NAVAN. 1960. Seasonal distribution of some epipelagic fishes in the Gulf of Alaska region. J. Fish. Res. Board Can. 17:221- 233. Nelson. D. R. 1974. Ultrasonic telemetry of shark behavior. Nav. Res. Rev. 27(12):1-21. Nel.son, D. R., and S. H. Gruber. 1963. Sharks: Attraction by low-frequency sounds. Sci- ence (Wash., DC.) 142:975-977. Nelson, D. R., and R. H. Johnson. 1972. Acoustic attraction of Pacific reef sharks: Effect of pulse intermittency and variability. Comp. Biochem. Physiol. 42A:85-96! PINKAS, L., M. S. OLIPHANT. AND I. L. K. IVER.SON. 1971. Food habits of albacore, bluefin tuna, and bonito in California waters. Calif Dep. Fish Game, Fish Bull 152, 105 p. QUAST, J. C. 1968. Observations on the food of the kelp-bed fishes. In W. J. North and C. L. Hubbs (editors). Utilization of kelp- bed resources m southern California, p. 109-142. Calif Dep. Fish Game, Fish Bull. 139. Roper. C. F. E., and R. E. Young. 1975. Vertical distribution of pelagic cephalo- pods. Smithson. Contrib. Zool. 209, 51 p. SCHULTZ, L. P., AND M. H. MALIN. 1963. A li.stofshark attacks for the world, /n P. W. Gil- bert (editor). Sharks and survival, p. 509-567. D. C. Heath and Co., Boston. !• Sciarrotta, T. C, and D. R. Nelson. 1977. Diel behavior of the blue shark, Prionace glauca. near Santa Catalina Island, California. Fish. Bull.. U.S. 75:519-528. SoKAL, R. R., and F. J. ROHl.F. 1969. Biometry. W.H. Freeman and Co., San Franc, 776 P- Stevens, J. D. 1973. Stomach contents of the blue shark {Prionace glauca L.) off south-west England. J. Mar. Biol. As.soc. U.K. 53:357-361. 1976. First results of shark tagging in the .North-east At- lantic, 1972-1975. J. Mar. Biol. Assoc. U.K. 56:929-937, STRASBURG, D. W. 1958. Distribution, abundance, and habits of pelagic .sharks in the central Pacific Ocean. U.S. Fish Wildl, Ser\'., Fish. Bull. 58:33.5-361. TE.STER, A. L. 1963. The role of olfaction in shark predation. Pac. Sci, 17:145-170, TRICAS, T. C. 1977. Food habits, movements, and seasonal abundance of the blue .shark, Prionace glauca (Carcharhinidael, in southern California water. M.S. Thesis. California State Univ., Long Beach. 79 p. vvkkks, a. 1974. Shark! NOAA 4(11,8-13. 182 LIFE HISTORY AND VERTICAL MIGRATION OF THE PELAGIC SHRIMP SERGESTES SIMILIS OFF THE SOUTHERN CALIFORNIA COAST Makoto Omori' and David Gluck^ ABSTRACT Sergestes similis in the southern California eddy was observed with respect to reproduction, daily and ontogenetic vertical migrations, growth, and longevity. The period of highest spawning activity occurs between late December and early April, but small pulses of spawning are occasionally observed in late spring and summer. The release of eggs takes place close to shore above the continental slope, and then the eggs sink to 200 m or deeper. Nauplius larvae ascend and protozoeal and zoeal laivae stay mostly above 100 m. The daily vertical migration becomes evident after the second protozoeal stage. Adults are abundant between 50 and 200 m at night and 2.50 and 600 m in the daytime. The spawning activity of .S. similis becomeshighest during the period when the verticaUhicknessof the optimum temperature zone (10^-15^Cl is the greatest. The authors speculate that the local population off the southern California coast may be joined by the subarctic population. It is possible that multiple spawnings occur from females of the southern California population. The lifespan ofS.sirntlis is 2.0-2.5 years for females and about 1.5 years for males. Sexual maturity is reached at about 1 year in both sexes. Females reproduce in two successive spawning seasons, and males seem to accomplish multiple fertilizations. Growth trends are similar to those reported for S. similis off Oregon. Growth rates are described using growth curves fitted by the von Bertalanffy and logistic equations. Sergestes similis Hansen is the most abt lani. oceanic, pelagic shrimp in the Nonh Pacific Drift, lat. 40°-50°N. This subarctic a- i transitional species occurs mainly in watei. rthfre t mpera- ture ranges between 3° and 13 J. Its di.-; ration extends from Japan to the coast of North America as far south as lat. 27°N (Pearcy and Forss 1969: Omori at al. 1972). In the cooler part 5.0 mm were sorted, counted, and sexed. The carapace length from the tip of the rostrum to the posterior margin of the carapace at the dorsal midline was measured to the nearest 0.5 mm. Change through time in the carapace length- frequency histograms of S. similis was graphi- cally analyzed using probability paper (Harding 1949; Cassie 1954). In order to compare the growth trends of the S. similis population off southern California with trends in other waters, previous data on the size-frequency distribution of S. similisreporie6 by Genthe (1969), Pearcy and Forss (1969), Omori et al. (1972), and Mutoh and Omori ( 1978) were reanalyzed to obtain average or modal carapace lengths" for the populations at ■"Scripps Institution of Oceanography. 1965. Physical and chemical data CalCOFI cruise 6401. 10 January-4 March 1964. SIO Ref. 65-7, 76 p. ^Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOA-'V. *BL/CL regression of Sergestes similis < >.5.5 mm CL) are as follows: 186 OMORl and GLUCK LIFE HISTORY OF SERGESTES SIMILIS different sampling dates and locations. The von Bertalanffy and logistic equations were used to fit these growth data. RESULTS Daily and Ontogenetic Vertical Migrations of Larvae and Earl)' Postlarvae Coastal upwelling is generally weak in south- ern California during the winter (Bakun 1973). This is consistent with the data on environmental properties at the sampling stations (Figure 2). The thermocline remained at about 75 m at all stations on Line 60 with the mixed layer temperature ranging from 1L5°C inshore to 14.0°C offshore. Salinity was usually <33.30%o in water above 75-m depth. On Line 90, except for the two outer- most stations, the thermocline was at 30-50 m and the temperature within the mixed layer was >13.5°C. Salinity was >33.20%oat all depths. On Line 100 the thermocline was at about 50 m at Stn. 100.35 and 100.60. Temperature within the mixed layer was about 15°C, and salinity was >33.50%o. The position of the oxycline coincided with that of the thermocline at nearly all stations. Generally, the oxygen level at depths below the mixed layer increased going seaward. The main population of S. sirnilis larvae was always between the surface and 100-m levels, and they occurred in greater abundance at stations on the continental slope (Figure 3). The population density was highest at Stn. 90.32 (101 individuals/m^). The larvae did not occur at Stn. 90.120, 90.140, and 100.120. In these southern offshore stations the temperature above 100 m was >16°C. The temperature-salinity curves characterized the water mass as eastern North Pacific Central water, where S. si mil is has never been found. In this water mass, the J'ortmanni type" larvae (the Sergestes corniculum group, see Yaldwyn 1957 and Omori 1974) were commonly distributed. The vertical distributions of larvae and early postlarvae from eight stations where they were abundant shows that the larvae were scattered BL = 3.15 + 2.85 CL for females. BL = 2.55 + 3.11 CL for males (Omori etal. 1972). The regression for juveniles with carapace length 5.5 mm or less BL 3.08 CL. from 20 to 100 m during the daytime (Figures 4, 5). On Line 90, the distribution pattern did not coin- cide well between the stations closest to shore (Stn. 90.28 and 90.32) and the offshore stations (Stn. 90.60 and 90.70). At Stn. 90.60 in the day- time, the larvae were widely distributed through- out the 0-110 m layer, but larvae occurred only between 44 and 88 m at Stn. 90.32 during the day. The greatest population density observed was within the 66-88 m layer at Stn. 90.32 (about 3,500 individuals/1,000 m^). Nighttime larval distribu- tion was between 20 and 90 m at Stn. 90.70, but again, it was below 40 m at the closest inshore station. A similar inshore and offshore as- semblage was observed along Line 100, although the vertical distribution of the larvae was ex- panded more widely. At Stn. 100.35 the larvae were most abundant between 50 and 100 m in the daytime and and 80 m layer at night. On the other hand, at Stn. 100.60 the main population in the daytime occurred between 20 and 120 m, while at night the distribution ranged from the surface to 140 m with considerable numbers in the 0-40 m layer. At both stations, there was a clear daily vertical migration of the main population of zoeal and postlarval stages. With the present sampling method, there was some doubt whether the same population was measured by day and night tows. However, as indicated in Figures 4 and 5, the estimates of abundance beneath 1 m^ of sea surface did not differ appreciably between day and night at the two closest stations on Lines 60 and 90 and be- tween day and night tows at the same station on Line 100. It can be said, at the least, that the avoidance of nets by larvae in the daytime was no greater than at night. When abundance vs. depth is combined and av- eraged for each larval stage at each station, the extent of daily vertical migration becomes clear. The first protozoeal stage shows at least a re- stricted daily vertical migration (Figure 6). The larvae gradually increase their range of vertical distribution with growth while gradually inhabit- ing deeper water. Thus, the main population of early postlarva (40-45 m at night and 70-75 m in the daytime) shows a deeper distribution than ear- lier larval stages. Eggs of S. sirnilis (about 0.3 mm in diameter) were slightly heavier than the density of the ex- perimental water; the difference in sinking rates was not significant at the 59c level between 1 0° and 14"C under laboratory conditions (Table 3). 187 FISHERY BULLETIN VOL 77, NO 1 Temperature (°C) 5 10 15 20 I I I I I I I I I I I I Salinity ( /oo) 33.00 34.00 a. LU 400 Figure 2. — Vertical profiles of temperature, salinity, and oxygen on CalCOFI Lines 60, 90, and 100, January-February 1964, off southern California. 188 OMORI and GLUCK: LIFE HISTORY OF SERGESTES SIMIUS 130° 125° 120° ESTIMATED ABUNDANCE UNDER I m2 OF SEA SURFACE M 60+ no 40° Figure 3. — Distribution and abundance of Sergestes smiths larvae from January to February 1964, Estimated abundance is expressed as number of mdividuals beneath 1 m^ of sea surface m depths between and 100 m. Table 3. — Experimental data on sinking velocity of eggs of Sergestes simihs in water of salinity 33.72%o. Difference in sink- ing rates is not significant at the S'J level. Replicates Sinking velocity (m/h) Temperature ( C) Average SD Range 10 14 9 9 145 044 091-2 19 181 , 52 1 04-2 99 Spawning Season The highest spawning of S. similis took place from late December to early April. Protozoea lar- vae occurred most abundantly between January and April at Stn. 90.37 (Figure 7), but were not found in samples collected in November and De- cember. During 1951-54, a number of PZ2 and PZ3 appeared each year between January and July, but the occurrence of PZl was restricted to January- April, except for August 1952 and July 1954. Although one-third of the autumn months were not represented by samples, these months were scattered enough to make the data sig- nificant. Seasonal abundance of zoeal stages dup- licated that of PZl. Early postlarvae were found in plankton from February to early July. Consider- able numbers of PZl and PZ2 (<1.3 mm BL) ap- parently passed through the mesh of the CalCOFI net, as their measured population densities were almost always lower than those measured for PZ3. The optimum temperature range for larval de- velopment is 10'-15°C(Omori 1979), and the high- est temperature at which adult S. similis occur is 13°C. Thus, the best temperature for the larvae is close to the upper temperature limit of the adult's habitat. Furthermore, comparison of the repro- ductive activity of S. similis with physical and 189 FISHERY BULLETIN, VOL 77, NO 1 NO OF INDIVIDUALS / 1000 m^ Figure 4. — Vertical distribution of larvae and postlarvae of Sergestes similis on CalCOFI Lines 60 and 90 off southern California. PZ, protozoeal stages: Z, zoeal stages; PL. postlar- val stages. Estimated total number of larvae beneath 1 m^ of sea surface indicated by n. chemical environmental data indicates that there is a relationship between temperature and spawn- ing season (Figure 7). Spawning activity was highest during the period when the vertical stratum of optimum temperatures for larvae was thickest. It decreased before colder water was brought in by coastal upwelling which was nor- mally most intense from May to August (see Bakun 1973). A seasonal minimum, or cessation, of spawning occurred during the summer and au- tumn when the upper layer was covered by un- favorably warm temperatures (>15°C). Growth Because of the smaller mesh size, the 6-ft I KMT retained a larger proportion of small shrimp than did the 10-ft IKMT (Figure 8). While specimens of 4 mm CL occurred in the smaller net, few < 7 mm were retained in the larger net. Well-defined progressions of size-frequency modes gave indications of average growth rates for certain cohorts, although we sometimes encoun- tered difficulties in interpreting these trends due to inadequate sampling, and possibly to extended spawning of the species. One 1975 cohort (12.0- 14.5 mm CL) and two conspicuous 1976 cohorts (5.0-11.0 mm CL) were seen in females collected in August 1976 (Figure 8A). The former cohort was not found in the following two samplings. The large-sized 1976 cohort (mean modal length, 8.4 mm CL in August) reached 9.9 mm CL in October, 10.5 mm CL in January, and 11.8mmCLin March 1977. Growth of the small-sized cohort was trace- able until April 1977, when the shrimp attained an average carapace length of 10.4 mm. Recruit- ment of postlarvae <6.0 mm CL ( 1977 cohort) was intense in April. The histogram for March showed only a single mode of males, and it isnot possible to Figure 5.— Vertical distribution of lar- vae and postlarvae of Sergestes similis at CalCOFI Stn. 100.35 and 100 60 off southern California. Estimated total number of larvae beneath 1 m^ of sea sur- face indicated by n. 100 NO OF INDIVIDUALS / 1000 m^ IO(X) \ 10 100 1000 ^ 10 100 ICXXD \ 10 100 1000 J 190 OMORI and GLUCK: LIFE HISTORY OF SERGESTES SIMILIS RELATIVE ABUNDANCE (%) 20 40 20 40 20 40 20 40 20 40 20 40 60 J I I FIGLIRE 6. — Vertical distribution of larvae andpostlarvae of Sergestessimilisoff southern California. Abundance vs. depth at all sampling stations was combined and averaged. Horizontal line indicates the depth at which the cumulative catch represented 509c of the total catch. PZ, protozoeal stages; Z. zoeal stages; PL, postlarval stages. say whether this 1976 cohort represents the large-sized group or not. In the 10-ft IKMT sam- plings the most conspicuous female cohort of 10.5-13.0 mm CL in April reached 13.5-15.5 mm CL in October (Figure 8B). The males grew from an average 10.8 to 11.7 mm CL between April and August. In many cases, the size structure of the population showed the presence of only one or two obvious size groups, but in three cases (April 21, June 21, and July 29) the histograms of females indicated three size groups. Development of the smallest cohort of age-group was traceable until August in both females and males, but in October and November, two cohorts of age were appar- ent. Some estimates of growth were attempted using changes in the average or modal lengths in vari- ous months. In order to show the growth trend more definitely, the results of all previous length measurements of S. fiimilis from various waters were reanalyzed and the average or modal lengths for each size group were plotted together with the present data (Figure 9). Except for the points de- rived from the offshore population in the subarctic North Pacific, where the environment is quite dif- ferent from that of southern California, the major- ity of cohorts had average or modal lengths which fell within the growth curves of three year classes fitted by eye. These data indicate the following: 1 ) as expected from spawning season data, in most cases the modal progressions are evident starting in winter or early spring, 2) growth trends of S. siriiilisoff southern California appear similar to the popula- tion off Oregon (Pearcy and Forss 1969), and 3) growth rates do not vary greatly among many different populations, although there is evidence that a few modal groups grew about twice as rapidly as the ordinary one. The ratio of females to males in all collections was 1.3:1 (553:422). Sex ratio in a cohort was not skewed greatly towards females until the modal length of the female population reached about 13 mm CL. At that point, the males of the cohort rapidly disappeared from the collection, account- ing for the observed imbalance in sex ratio (69:2). DISCUSSION Ontogenetic Migration Omori (1979) found experimentally that: 1) ovigerous females of S. similis shed their eggs at night, 2 1 the eggs took 105 h to hatch into nauplii 191 FISHERY BULLETIN VOL. 77, NO. 1 1953 n PZ I I 1 PZ 2,3 n z 1,2 JFMA MJ J A S N D MONTHS FIGUREV.— Isotherms of 10° and 15'C and occurrence of larvaeof Sergestes stmdis at CalCOFI Stn. 90,37. 1951-54, off southern California at 0-140 m. Shadow indicates zones where tempera- tures exceed the average 10°- 15°C range of 1 950-55, No samplmg indicated by ns. PZ, protozoeal stages; Z, zoeal stages. at lO^C, and 3) mortality increased greatly in temperatures beyond 10°-15°C. We do not know the depth where spawning and hatching of S. similis take place in the natural habitat. How- ever, the laboratory observations, coupled with biological information on the other species of sergestids and euphausiids (Omori et al.^), indi- cate that the eggs of S. similis are shed in shallow water at night when ovigerous females rise up- wards. Adult S. similis seldom occur above the 50-m level at night where the temperature is usu- ally >13°Coffsouthern California. Assuming that AUG 19, 1976 UNSEXEDr-, FEMALES oiJ r^., , ^n^ .IPJ CO < UJ N X o < tr UJ m 3 10- MALES :^ 10 12 14 6 8 10 12 10- 10- CO < _1 o N CO < LlI 10- 2 cr 3 10- APR 12,1972 FEMALES jzO. JUNE 21,1953 n -fl JULY 29, 1973 -n^ 1 ^ l ^p AUG 24,1954 Ff ^PP^ i 22„, OCT 28,1972 '\\ 10- I \ r NOV 8 , 1975 MALES &^ -f=^ ^ -) — t — I — I — r 10 12 14 16 8 10 12 CARAPACE LENGTH (mm) 'Omori, M., M. Mutch, and M, Kaetsu, 1974, Prediction of Sergia lucens fishery in 1974/75 season. |In Jpn.l Unpubl. manuscr., 5 p., distributed at the annual meeting of the "Sakura-ebi" Fishing Unions. Shizuoka Prefecture. Japan. Figure 8. — Length-frequency histograms of Sergesles simitts collected with a 6-ft IKMT ( Ai and a lO-ft IKMT (B) off southern California. The samples were arranged m monthly order regard- less of the year of .sampling. Lines trace development of sig- nificant cohorts. 192 OMORl and GLUCK LIFE HISTORY OF SERGESTES SIMILIS 0»0^<1^D«*— I — ICSII^OCTLTiUDr-^CJOcn CD X o 6 i ■^£■5 si a £ QD cfi E O (^^) H19N3n 33VdVdV3 ■^ 0) a Im c e c£ to *' t: -a ■Si o § at CO CO o lT T3 t-. ^ u Cd 73 U cd 3 H) o eg a. Cfl CJ w T3 I- -2 1 in cC J-T X S -o E 55 Ol o c c CJ « o (> u ■c s iS CO 0) o X 0^ CJ Wl TJ C o c Oi 3 T3 C o tfl a" C bD ■x) S ffl a> c 01 05 41 o o cd CO C ^ o S ^ o "« -i o -c s "cd 1 "o 'S E oi C/3 d oT o o a. CO £ cd CO CD u. u o 193 FISHERY BULLETIN: VOL 77. NO, I spawning takes place around 50 m and using data on both the sinking velocity of the eggs and the development time of eggs at 10°C, we can estimate that the eggs sink to about 220-m depth before hatching. The ambient temperatures which eggs may encounter during their descent are 7°-13°C. It is probable that some eggs are laid deeper than 50 m. However, like the population off the Oregon coast (Pearcy and Forss 1969), S. similis is seldom distributed over the continental shelf off southern California. Therefore the majority of eggs would not sink to the bottom but remain within the water column. A comparison of vertical distribution patterns at all stations confirms the following hypotheses: 1) the occurrence of larvae is restricted to water <140 m where the temperature range is 9°-16°C, 2) the larvae often appear in the 0-20 m level at night but rarely in the daytime, and 3) the larval distribution is more restricted inshore than offshore to a limited vertical range. The descent of eggs and ascent of naupliar larvae are well documented in the oceanic euphausiid £Mp/ia(/sia superba and Meganyctiphanes norvegica (Mauchline and Fisher 1969). Presumably the nauplii of S. similis rise from 200 m or deeper to layers where the temperature is usually > 10°C. In this manner, the nauplius, which is probably highly vulnerable to predation, develops in the less hazardous layers which are deeper than the following larval stages. Protozoeal and zoeal lar- vae stay mostly in the shallower environment which is relatively rich in food (phytoplanktonand microzooplankton). They perform daily vertical migration starting PZl, and their downward mi- gration at daytime becomes more marked with each stage. This hypothesis is further supported by the positive phototaxis in N3 to PZl larvae and negative phototaxis after PZ2 observed in the laboratory (Omori 1979). According to Omori (1974), the larvae of pelagic shrimps can be classified into several types on the basis of their ontogenetic migration. The first group is composed of the species living in the epipelagic and upper mesopelagic zones. Their larvae perform migration within the euphotic zone. Sergestes similis belongs to this group, hav- ing a similar pattern to that described for Sergia lucens (Omori 1974), but the negatively buoyant eggs of Sergestes similis differ from Sergia lucens eggs which have density similar to seawater. Adult Sergestes similis were abundant inshore off Oregon during the winter, but they tended to shift to an offshore distribution during the sum- mer (Pearcy and Forss 1969). This inverse rela- tionship between nearshore and offshore stations indicates a horizontal ontogenetic migration of this species by active swimming with the help of subsurface currents. The movement by a species to nearshore regions for spawning is a characteris- tic behavior among several sergestid shrimps (Omori 1974). Relationship Between Spawning Season and Environment Larvae of S. similis, in particular PZl, were more abundant inshore than offshore, which indi- cates that the spawning of S. similis is taking place mainly close to shore above the continental slope off southern California (but not as far in- shore as the continental shelf). The assumption by Pearcy and Forss (1969) that S. similis in the Oregon population spawns during most of the year with a seasonal minimum occurring during the summer was partially true in the southern California population as there were small pulses of spawning in summer and autumn. However, the southern California adult population appears to be recruited largely from the local population spawned from late December to early April. One may argue that the decrease of larvae in the study area in summer and autumn was caused merely by the seasonal change off the southern California gyre. It would be interesting to compare our data with samples from stations outside of the northward flowing path of the gyre. However, we do not think that such an extreme absence of lar- vae in summer and autumn is taking place with the year-round spawning of S. similis. At least some larvae should have successfully remained in the study area to yield noticeable recruitment dur- ing those months. Incidentally, females having fully developed ovaries (Omori 1979) were sel- dom found in the IMKT collection from summer and autumn. Genthe (1969) assumed that maximum reproductive activity of S. similis from the Santa Barbara Channel was in summer and autumn, but his assertion that juveniles collected in August of 5.0-6.5 mm CL are 11 or 12 mo old is misleading. Shrimp of this size are more likely to be of the 6-7 mo class. Omori et al. (see footnote 7) studied the relation- ship between environments and reproductive be- havior of another sergestid, Sergia lucens. in Suruga Bay, Japan, and found that the com- 194 OMORI and GLUCK: LIFE HISTORY OF SERGESTES SIMILIS mencement of spawning and the survivorship of larvae are closely related to the ambient tempera- ture rather than the quantity of food available. This study showed that: 1) S. lucens started spawning in June, immediately after the tempera- ture exceeded 18°C at 20-50 m, and the number of larvae increased with increasing vertical thick- ness of the optimum temperature zone for the growth of larvae (18°-25°C), 2) the population size of S. lucens was determined by the abundance of larvae during the first half of the breeding season, June- August, and 3) the abundance of larvae was often related to the fluctuation in vertical width of the optimum temperature zone. During midsum- mer the warming of surface waters above to 25°C and the shoaling of cold water < 18°C restricted the optimum temperature zone, and consequently the mortality of protozoeal larvae increased. As with S. lucens , a rise in temperature may trigger the commencement of spawning of the Sergestes similis population in the northern sub- arctic waters where surface temperature is < 10°C during most of the year. However, this seems not to be the case for the southern California popula- tion where favorable temperatures were available year-round in some stations between 50 and 100 m. Yet, the spawning began abruptly when the temperature around 100-m depth began to rise. Abundance of larvae was greatest during the period when the vertical thickness of the optimum temperature zone was the greatest, and spawning activity almost ceased both when the ambient temperature was lowered by coastal upwelling and when warm surface water subsequently ap- peared. Thus, the spawning season of S. similis is not always positively correlated with the upwell- ing which causes environmental enrichment and subsequent increase of plankton biomass in the southern California eddy. The correlation of spawning to coastal upwelling in Euphausia pa- ct fica , another very abundant species of the California Current zooplankton assemblage, is the most striking difference affecting the spawn- ing seasons of that organism and S. similis . Simi- lar to S. similis, the southern California popula- tion of E. pacifica seems to be adapted for larval development between 12°and 16°C, but its spawn- ing is highest when coastal upwelling is strongest in May-June (Brinton 1976). Although true mechanisms remain unexplained, we theorize that the distinctive spawning season of S. similis in southern California is based mainly on the adaptation of this species to the vertical thickness of optimum temperature. The vertical thickness of the optimum temperature zone was also corre- lated with the abundance and survival of larvae of S. similis. The cumulative depths of the optimum temperature ranges for S. similis from January to March were 220, 318, 311, and 380 m from 1951 to 1954 whereas the average numbers of protozeal larvae occurring from January to April were 129, 218, 224, and 543 individuals/1,000 m^, respec- tively. In 1951, zoeal larvae were found in the lowest numbers when the cumulative depth was the smallest. One possible interpretation of the irregular small pulse of spawning of S. similis in seasons other than winter and early spring is that shrimp which reproduce during these periods are carried from northern offshore waters, i.e., subarctic North Pacific, to the study area. If temperatures of 9°-10°C in the habitat of S. similis really trigger the commencement of spawning, those living in subarctic waters would start spawning later than July in most areas. The yearly mean velocity of the eastward component of the North Pacific Drift is about 3 cm/s at the surface in the areas lat. 45°N west of long. 150°W. On the other hand, a strong south-flowing current, which flows at the velocity of 5-10 cm/s but occasionally >20-30 cm/s is ob- served throughout the year both at the surface and at 200-m depth off the west coast of the United States ( Wyllie 1966; Stidd'*). If part of the popula- tion of S. similis near lat. 47°N, long. 140°W, e.g., where tremendous numbers are eaten by baleen whales (Omori et al. 1972), is carried southeast- ward by the currents, the shrimp can easily reach the southern California coast within 2 yr at a mean speed of 5 cm/s of flow. The spawning occurs in the summer off California due to continuous recruitment of such northern populations. An electrophoretic study of S. similis population may help to answer this question, although, due to di- verse trophic regimes, genetic variability of the southern California population may be too large to distinguish it from the subarctic population (see Valentine and Ayala 1976). Another possible interpretation is that the phenomenon is caused by the adaptation of the local population to mid latitude irregularities in oceanographic and trophic conditions. It has been observed for several penaeids, sergestids, and euphausiids in temperate and tropical regions ^Stidd.C.K. 1974. Ship drift components: means and stan- dard deviations. SIO Ref. 74-33, 57 p. 195 FISHERY BULLETIN VOL. 77, NO. 1 that the ovary may contain ova at different de- velopmental stages and that not all ova are neces- sarily released at once (King 1948; Mauchline 1968; Roger 1973; Omori 1974). We observed that S. simili.s off southern California always retained considerable numbers of immature ova after spawning. Because the volume of a pair of mature ovaries from this shrimp represents about lOT of the body volume, we can estimate from the volume of each egg that one female has at least 1 ,500 but probably closer to 2,000-2,500 eggs. Nevertheless, the number of eggs released by a female in the laboratory was always <1,140 (Omori 1979). Thus, as has been pointed out for Euphausia pa- cifica off southern California (Brinton 1976), it appears possible that under optimal environmen- tal conditions small ova of S. similis may develop later and produce a second spawning. If a female, which produced the first clutch in late December, released the second clutch 3-4 mo later, two modal size-groups might be seen sometimes in the same age-group. It is probable that unfavorable en- vironmental conditions would prevent the spent ovary from maturing again until the following year. Further evidence of this phenomenon is pro- vided by the increase in the number of spent females and the decrease in the number of fully grown ova in ovaries of S. similis off southern California and Oregon during the summer (Genthe 1969; Pearcy and Forss 1969). The length-frequency histograms in October 1972. November 1975. and from August 1976 to March 1977 (Figure 8) indicate either the occurrence of multiple spawnings for S. similis or individuals from farther north being mixed into the southern California population. Growth, Sexual Maturity, and Longevity If S. similis population is composed of age- group shrimp only and all attain sexual maturity after about 1 yi", the size structure of the popula- tion sampled shows the presence of only one or two size groups. However, the obvious occurrence of three size groups of females during certain periods of the year in this study indicates that the females ofS. similis live 2 yr or more. Large females, 13-16 mm CL, carrying developed ovaries are sometimes collected, indicating that S. similis can reproduce at least twice during its lifetime. The absence of male individuals >14 mm CL resulted in a strong imbalance of sex ratio, indicating that the males die out at an age of < 20 mo. Genthe ( 1969 ) showed evidence of sex reversal (protandrous herma- phroditism) from male to female in S. similis. Similar phenomena have been observed in other sergestids of the genus Acetes (Omori 1975). A detailed study is needed to determine the meaning of these findings, although at the present time we believe that the variance may be explained by abnormalities, since the frequency of occurrence is small. The bias in sex ratio favoring females above a certain size indicates the possibility of multiple fertilizations by males. Thus some females of the 2 age-group may mate with males of the 1 age- group. We obtained an average gi'owth trend of S. similis throughout its life by shifting the average or modal lengths of populations off the California and Oregon coasts horizontally in accordance with the month of their sampling. The growth of S. similis >6 mm CL was best fitted by the von Ber- talanffy equation (Figure 10): /, = 14.7(1 - e<"'03™') for females, and /, = 12.0(1 - e-o "MS") for males, where /, is the carapace length in millimeters at t days. Because of the large mesh sizes of the IKMT nets, however, any average or modal length calcu- lated from these samples over considerable size ranges on either side of 7 mm CL is probably greater than the length of the natural population. Therefore, the initial modal length of the 3-mo old population was fit by eye and connected with those growth curves of larval and early postlarval stages at 10° and 14°C which were obtained under laboratory conditions. It took 52 days for S. similis to reach the first postlarval stage at 14°C (Omori 1979). Under these conditions the logistic equa- tion (Figure lOB) seemed to give the better fit to the growth curves: / 14.7 1-e- 12.0 ' J _p-0.01254((-188.4) for females, for males. Growth is very rapid during the postlarval stages. The juveniles at 4-8 mo old grow, at 0.91 mm CL/mo, during the period from April to Au- gust (logistic equation). The biomass of total zoo- plankton, as well as young Calanus and Euphausia , which are considered to be the most important food for juvenile and adult S. similis. 196 OMORl and GLUCK LIFE HISTORY OF SERGESTES SIMILIS I5n Figure lO— Average growth of Sergestes stmtlis off the California and Oregon coasts. Solid lines (A) are growth curves fit by the von Bertalanffy equation and (Bl are those fit by the logistic equation. Dashed lines are growth curve of early developmental stages of 1 0° and 14°C determined in the laboratorj- lOmori 1979). ^,0 X H O LlI O < < FEMALE (B)^^__- o---^ FEMALE /o-:^5^-»-MALE(B) " -• MALE (A) o FEMALE • MALE i^ UNSEXED OR COMBINED -1 — I — \ — I — I — r n — I — I — I — I — i — I — r JFMAMJJASONDJFMAMJJASONDJFMAMJJA MONTHS usually peaks in the April-July period in southern California waters (Mullin and Brooks 1970; Brin- ton 1976). Shrimp which encounter the best feed- ing conditions probably grow rapidly with low mortality rates and form distinctive modal groups such as those traced in Figure 9. The growth rate gradually decreases after 10-mo old. and the females add only 5 mm CL in 20 more months before dying. The difference in growth rates be- tween the sexes becomes apparent after the shrimp attain a length of about 8 mm CL. The males grow slower than the females, but attain sexual maturity '2-I mo earlier than females be- cause the females become mature at 10.5-11.0 mm CL, whereas the males mature at 9.5-10.0 mm CL (see Genthe 1969; Omori 1979). Since five data points for females on the upper right-hand side of Figure 10 are on the asymptote, it is highly speculative whether these shrimps represent that age-group, or possibly an age-group spawned 5-6 mo later; in which case they would be placed on a different curve. It is apparent, however, that the longevity of the females of S. siinilis is more than 2 yr and that they spawn in two successive spawn- ing seasons during their lives. These observations agree well with those of Matthews and Pinnoi (1973) on Sergestes arciticus Kroyer, which is the most closely related species to S. similis ( Judkins 19721, in Kursfjordan, western Norway. ACKNOWLEDGMENTS We acknowledge the helpful reviews by M. M. Mullin and J. G. Morin. Thanks also to the staff and graduate students of the Food Chain Research Group of the Institute of Marine Resources for their assistance in sampling at sea. Omori is in- debted to the Institute of Marine Resources and the Marine Life Reseaixh Group of Scripps In- stitution of Oceanography for the financial sup- port and hosting of his visit. LITERATURE CITED AHLSTROM, E. H. 1948. A record ofpilchard eggs and larvae collected during surveys made in 1939 to 1941. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 54, 76 p Bakun, a. 1973. Coastal upwelling indices, west coast of North America. 1946-71. U.S. Dep. Commer., NOAA Tech. Rep ^fMFS SSRF-671, 103 p. B.^RHAM. E. G. 1957. The ecology of sonic scattering layers in the Mon- terey Bay area. California. Hopkins Mar. Stn.. Stanford Univ. Tech. Rep. 1. 182 p. 197 FISHERY BULLETIN: VOL. 77. NO. 1 1963. The deep-scattering layer as observed from the bathyscaph "Trieste". Proc. 16th Int. Congr. Zool. 4:298-300. BRINTON, E. 1967. Vertical migration and avoidance capability of euphausiids in the California Current. Limnol. Oceanogr. 12:451-483. 1976. Population biology of Euphausia pacz^ca off south- em California. Fish. Bull.. U.S. 74:733-762. C.'^SSIE. R. M. 1954. Some uses of probability paper in the analysis of size frequency distributions. Aust. J. Mar. Freshwater Res. 5:513-522. DAVIES, I. E., AND E. G. BARHAM. 1969. The Tucker opening-closing micronekton net and its performance in a study of the deep scattenng layer. Mar. Biol. (Berl.l 2:127-131. Fleminger, a. 1964. Distributional atlas of calanoid copepods in the California Current region. Part. 1 Calif Coop. Oceanic Fish. Invest.. Atlas 2. 313 p. GENTHE, H. C, Jr. 1969. The reproductive biology of Sergestes similis (De- capoda, Natantia). Mar. Biol. iBerl.l 2:203-217. Harding, J. P. 1949. The use of probability paper for the graphical analysis of polymodal frequency distnbutions. J. Mar. Biol. Assoc. U.K. 28:141-153. JUDKINS. D. C. 1972. A revision of the decapod crustacean genus Sergestes (Natantia, Penaeideal sensu lain, with emphasis on the systematics and geographical distribution of Neoser- gestes, new genus. Ph.D. Thesis, Univ. California, San Diego, 274 p. JUDKINS, D. C, AND A. FLEMINGER. 1972. Comparison of foregut contents of Sergestes similis obtained from net collections and albacore stomachs. Fish. Bull., U.S. 70:217-223. King, J. E 1948. A study of the reproductive organs of the common marine shrimp, Penaeus setiferus\ Linnaeus). Biol. Bull. (Woods Hole) 94:244-262. M.'^TTHEWS, J. B. L.. AND S. PINNOI. 1973. Ecological studies on the deep-water pelagic com- munity of Korstjorden, western Norway. The species of Pasiphaea and Sergestes (Crustacea Decapoda) recorded in 1968 and 1969. Sarsia 52:123-144. MAUCHLINE, J. 1968. The development of the eggs in the ovaries of euphausiids and estimation of fecundity. Crustaceana (Leidenl 14:155-163. MAUCHLINE, J., AND L. R. FISHER. 1969. The biology of euphausiids. Adv. Mar. Biol. 7,454 p. MULLIN, M. M., AND E. R. BRCOTKS. 1970. The ecology of the plankton off La Jolla, California, in the period April through September, 1967. VII. Produc- tion of the planktonic copepod, Calanus helgolan- dicus. Bull. Scripps Inst. Oceanogr. Univ. Calif. 17:89- 103. Mutoh, M.. and M. OMORI. 1978. Two records of patchy occurrences of the oceanic ^nmp Sergestes similis Hansen off the east coast of Hon- shu, Japan. [InJpn.l J. Oceanogr. Soc. Jpn. 34:36-38. OMORI, M. 1974. The biology of pelagic shrimps in the ocean. Adv. Mar. Biol. 12:233-324. 1975. The systematics, biogeography, and fishery of epipelagic shrimps of the genus Acetes (Crustacea, De- capoda, Sergestidae). Bull Ocean Res. Inst.. Univ. Tokyo 7. 91 p. 1979. Growth, mortality, and feeding of larval and early postlarval stages of the oceanic shrimp, Sergestes sinulis Hansen. Limnol. Oceanogr. 24:273-288. Omori, M., a. Kawamura, and Y. Aizawa. 1972. Sergestes similis Hansen, its distribution and im- portance as food of fin and sei whales in the North Pacific Ocean. In A. Y. Takenouti et al. (editors). Biological oceanography of the northern North Pacific Ocean, p. 373-391. Idemitsu Shoten, Tokyo. Pearcy, W. G., and C. A. FORSS. 1966. Depth distribution of oceanic shrimps (Decapoda; Natantia) off Oregon. J. Fish. Res. Board Can. 23:1135- 1143. 1969. The oceanic shrimp Sergestes simtlisoffihe Oregon coast. Limnol. Oceanogr. 14:755-765. PEREYRA. W. T.. W. G. PEARCY. AND F. E. CARVEY. JR. 1969. Sebastodes flauidus, a shelf rockfish feeding on mesopelagic fauna, with consideration of the ecological implications. J, Fish. Res. Board Can. 26:2211-2215. Roger, C. 1973. Biological investigations of some important species of Euphausiacea iCrustaceal from the equatorial and south tropical Pacific. In R. Fraser (editor). Oceanog- raphy of the South Pacific 1972, p. 449-456. New Zealand National Commission for UNESCO, Wellington. scripp.s institution of oceanography. univer.sity of California. 1963. Oceanic observation of the Pacific. 1951. Univ. Calif. Press, Berkeley and Los Ang., 598 p. 1965a. Oceanic observations of the Pacific: 1952. Univ. Calif Press, Berkeley and Los Ang.. 617 p. 1965b. Oceanic observations of the Pacific: 1953. Univ. Calif. Press, Berkeley and Los Aug., 576 p. Valentine, J. W., and F. J. Ayala. 1976. Genetic variability in krill. Proc. Natl. Acad. Sci. USA 73:658-660. WYLLIE, J. G. 1966. Geostrophic flow of the California Current at the surface and at 200 meters. Calif. Coop. Oceanic Fish. Invest., Atlas 4, 288 p. YALDWYN, J. C. 1957. Deep-water Crustacea of the genus Sergestes (Deca- poda, Natantia) from Cook Strait, New Zealand. Zool. Publ. Victoria Univ. Wellington 22:1-27. 198 THE OCEANIC MIGRATION OF AMERICAN SHAD, ALOSA SAPIDISSIMA, ALONG THE ATLANTIC COAST Richard J. Neves' and Linda Depres^ ABSTRACT The migratory route of American shad. A/osa sapidissima. in the Atlantic Ocean was studied using 14 yr of catch data collected during bottom trawl surveys by the U.S. National Marine Fisheries Service (and its predecessorl and cooperating foreign countries. All shad catches occurred at bottom tempera- tures from 3° to 15°C. with the most frequent catches between 7° and 13°C. Water temperatures between initial and peak entry of shad into home estuaries along the Atlantic coast are within the same thermal regime (3^-15^C). During the summer, ail shad catches occurred north of lat. 40^N in two primary areas; Gulf of Maine and an area south of Nantucket Shoals. Previous studies on food habits and differences in time of capture during National Marine Fisheries Service surveys indicated that shad were vertical migrators, probably following the diel movements of large zooplankters in the water column. Shad were generally absent from the Gulf of Maine by late autumn, and concentrations were found between lat. 39° and 4 1 °N during the winter. Based on previous tagging studies. National Marine Fisheries Service surveys, and coastal temperature data, most prespawning adults enter coastal waters along the Middle Atlantic Bight from lat. 36' to 40°N and then proceed north or south to natal rivers. Coastal surveys for river herring by North Carolina's anadromous fishery research program and commercial shad catches re[)orted to the International Commission for the Northwest Atlantic Fisheries by member nations concur with our proposed bottom temperature (3°-15^^C)-migratory route hypothesis for shad. The American shad, Alosa sapidissima, is an anadromous fish ranging from the St. Johns River, Fla., to the St. Lawrence River, Canada i Walburg and Nichols 1967). Meristic and tagging studies indicate that discrete spawning populations of shad exist in river systems along the Atlantic coast (Mollis 1948; Hill 1959; Nichols 1960. 1966; Carscadden and Leggett 1975a). Juveniles leave freshwater in autumn and generally remain in the ocean for 3-5 yr before returning to their natal rivers to spawn. Spawning runs occur in a south to north temporal progression, beginning as early as December in Florida and as late as June in Canada (Walburg 1960). Virtually all shad south of Cape Hatteras, N.C., die after spawning, whereas the percentage of repeat spawners in rivers north of North Carolina increases with latitude I Leggett 1969; Chittenden 1975). A considerable amount of literature exists on this species because of its commercial and recre- ational importance inshore, but little research has 'Massachusetts Cooperative Fishery Research Unit, Depart- ment of Forestry and Wildlife Management, University of Mas- sachusetts, Amherst, Mass.; present address; Virginia Coopera- tive Fishery Research Unit, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061. " ^Northeast Fisheries Center Woods Hole Laboratory, Na- tional Marine Fisheries Service. NOAA, Woods Hole, MA 02543. Manuscript accepted .August 1978. FISHERY BULLETIN VOL. 77. NO 1.1979 been done on the oceanic phase of its life history. Talbot and Sykes (1958) provided the first evi- dence of an annual oceanic migration based on 19 yr of tagging studies by the U.S. Fish and Wildlife Service. Tag returns indicated that shad from U.S. rivers congregated with those from Canadian riv- ers (Vladykov 1950. 1956) in the Gulf of Maine during summer and autumn and moved south to possibly overwinter off the Middle and South At- lantic States (Talbot and Sykes 1958; Walburg 1960; Walburg and Nichols 1967; Cheek 1968). In the spring, shad moved north or south toward natal rivers to spawn. Temperature monitoring in rivers with major shad runs, and laboratory experiments, have pro- vided convincing evidence that the timing of diad- romous movements corresponds with specific water temperatures (Walburg and Nichols 1967; Chittenden 1969, 1972; Williams and Bruger 1972; Leggett and Whitney 1972; Leggett 1973). Leggett and Whitney (1972) also postulated that the oceanic distribution of shad was temperature- controlled; tag returns plotted on surface isotherm charts fell within the 13°-18°C isotherms. How- ever, all of the tag returns used to establish this "migrational corridor" at sea were collected in- shore during the spring coastal migration toward 199 FISHERY BULLETIN VOL 77. NO 1 home rivers. The correlation between offshore dis- tribution and surface temperatures was therefore based on extrapolation. The U.S. shad fishery is essentially an inshore operation and commercial catch records have lim- ited value in evaluating the distribution of shad at CAPE HATTERAS sea. Previous tagging studies have relied on other commercial fisheries for offshore tag returns, but these fisheries concentrate effort at a time or place where principal species aggregate. Tag returns from shad taken as bycatch may therefore contain a geographical bias and reflect only the distribu- tion of fishing effort. This paper examines offshore collections of shad from 14 yr of bottom trawl sur- veys by United States and foreign research vessels and interprets available literature on the coastal occurrence of shad. An alternative temperature- based hypothesis is presented to explain the offshore migratory cycle of shad. METHODS The U.S. National Marine Fisheries Service (NMFSi and its predecessor have conducted au- tumn bottom trawl surveys since 1963 using the RV Albatross IV and the RV Delaware II. The survey area extends from Nova Scotia to Cape Hatteras, out to 366 m (200 fm) (Figure 1) and is stratified into geographical zones based on depth and area. Coastal sampling stations are outside the 27-m (15-fm) depth contour. Middle Atlantic stations between New Jersey and Cape Hatteras were added during autumn 1967. A stratified ran- dom sampling design is used in the surveys; trawl stations are allocated to strata in proportion to stratum area and randomly assigned within strata (Grosslein 1969). A standard No. 36 Yankee bottom trawl with a 1.25 cm stretched mesh cod end liner is towed at each station for 30 min at an average speed of 3.5 kn. Autumn surveys were conducted 24 h/day during 1963-76, between 3 September and 16 December. Spring bottom trawl surveys have been con- ducted by NMFS since 1968 over the same geo- graphical area (Figure 1). The No. 36 Yankee trawl was used from 1968 to 1972 and a larger No. 41 Yankee trawl from 1973 to 1976. Trawling pro- cedures were the same as during autumn surveys and occurred between 4 March and 16 May. A detailed description of NMFS bottom trawl sur- veys and survey procedures is provided by Flescher-' and Grosslein.'' In addition to U.S. cruises, periodic autumn trawl surveys were conducted cooperatively with Figure L— National Marine Fisheries Service bottom trawl surve.v area between 27 and 366 m. Cape Hatteras. N.C.. to Nova Scotia, western North Atlantic. ^Flescher, D. 1976. Research vessel cruises. 1963-1975 National Marine Fisheries Service Woods Hole, Massachusetts. NMFS, Woods Hole, Mass., Lab. Ref. No. 76-14, 30 p. "Grosslein, M, D, 1969. Groundfish survev methods. NMFS, Woods Hole, Mass., Lab. Ref. No. 69-2, 34 p. 200 NEVES and DESPRES: OCEANIC MIGRATION OF AMERICAN SHAD the U.S.S.R., Poland, and France from 1969 to 1976, mainly between Georges Bank and Cape Hatteras. Spring trawl surveys, intended primar- ily as juvenile herring surveys, have been made since 1973 by vessels from U.S.S.R., Poland. Ger- man Democratic Republic, and Federal Republic of Germany between Nova Scotia and Cape Hat- teras. Most of the foreign surveys followed NMFS sampling procedures, sampled all or selected strata wiihin respective survey areas, but used various types of bottom trawls. All spring and autumn surveys and additional cruises during summer and winter are summarized in Table 1. Survey station and catch data pertinent to this study included: date, location, time, depth, bottom and surface temperatures, and number, length frequencies, and weight of shad caught. We plotted catch locations from all surveys (Ta- ble 1) by 10' rectangles of latitude and longitude on depth contour maps according to month or sea- son. Locations of shad collections during spring (March-May) and autumn (September-November) were plotted by month. Summer (June-August) and winter (December-February) surveys were grouped by season because of less sampling effort and lower catch frequency. Commercial shad catches by month reported to the International Commission for the Northwest Atlantic Fisheries (ICNAF) by member nations from 1970 to 1975 were provided by Hodder'" and used to define major shad catches within each ICNAF division and their correlation with distribution patterns based on survey data. Surface and bottom temperatures (nearest 1°C) were plotted for each trawl tow that collected shad; foreign catches with missing tem- perature data were omitted from this analysis. Additional oceanographic data on temperature ( Walford and Wicklund 1968; Colton and Stoddard 1972; Churgin and Halminski 1974; U.S. Coast Guard Oceanographic Unit^) and oceanic currents (Bumpus and Lauzier 1965; Stommel 1965; Bum- pus 1973) were reviewed for seasonal patterns along the Atlantic coast. RESULTS Bottom trawls at 10,435 stations during the 77 Table l, — Summary of bottom trawl surveys conducted by United States and foreign research vessels between Cape Hat- teras, N.C, and Nova Scotia, 1963-76, =V. M. Hodder. ICNAF Office. Dartmouth. N. S., Canada B2Y 3Y9. pers. commun. July 1977. ■^U.S. Coast Guard Oceanographic Unit. 1970, 1975. Monthly temperature charts. January to December 1970. January to December 1975. available US Coast Guard Oceanographic Unit. Bldg 159-E Navy Yard Annex. Washington, DC 20590 No ol No ol Season Country surveys stations Inclusive dales Spring United Slates 15 2,514 4 Mar -16 May Foreign 10 597 26 Feb -29 May Summer United Stales 4 810 7 July-28 Aug Foreign 6 618 9 Aug -3 Sepi Autumn United Stales 21 3,657 3 Sepi-16 Dec Foreign 18 1.676 3 Sepl-11 Dec Winter United Slates 3 563 16 Jan -8 Apr Totals 77 10,435 surveys collected 4,770 subadult and adult shad at 527 stations throughout the survey area. United States and foreign research vessels accounted for 315 and 212 of the successful collecting stations, respectively. Shad ranged in size from 8 to 50 cm fork length (FL). Surface and bottom tempera- tures were recorded at 448 of these stations and used to plot catch frequency at 1°C intervals. Shad were collected at survey stations with surface temperatures between 2° and 23°C, and frequent catches occurred throughout most of this temper- ature range (Figure 2). Bottom temperatures at successful collecting stations ranged from 3° to 15°C, but primarily between 5° and IS'C (Figure 3). Most stations with bottom temperatures <3°C occurred in the Gulf of Maine during late winter and early spring; stations with bottom tempera- tures >15°C were mainly off the mid-Atlantic coast during late summer and early autumn. This apparent relationship between shad occurrence and bottom temperatures was examined further by comparing the catches of shad with total sam- pling effort at each temperature (Table 2). Bottom temperatures during surveys ranged from 1° to 23°C, but shad were captured only between 3° and 15°C. Shad catches occurred more frequently at li Flcl'RE 2 — Surface temperatures at 448 stations where Ameri- can shad were collected during bottom trawl surveys, 1963-76, Cape Hatteras, N.C, to Nova Scotia. 201 FISHERY BULLETIN: VOL, 77, NO. I 60 r 540 « J30' •s k J 20 a Z 10 J L 5 6 7 8 9 10 11 12 13 14 IS 16 17 Bottom Temperature °C Fu:URE 3. — Bottom temperatures at 448 stations where Ameri- can shad were collected during bottom trawl surveys, 1963-76, Cape Hatteras. N.C.. to Nova Scotia. Table 2. — Total sampling effort, number of shad catches, and percent catch frequency of shad at each bottom temperature during bottom trawl surveys, 1963-76, Cape Hatteras, N.C., to Nova Scotia. Bottom temperature (C) Total no of trawls Trawls witti shad 1 2 3 4 5 6 7 B 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 16 104 270 567 987 964 1,047 997 909 750 741 739 626 333 164 71 56 41 30 29 34 19 5 7 16 41 40 55 50 45 40 54 48 37 12 3 2 59 2 82 4 15 4 15 5,25 502 495 533 7 29 6 50 591 3 60 1 83 temperatures between 7" and 1.3°C, with the greatest capture frequency at 11°C (Table 2). Ocean depths at stations with shad ranged from 20 to 340 m, but most of these stations (65'7f ) were <100 m deep (Figure 4). Of the 527 successful collecting stations, 269 iBW) occurred at depths between 50 and 100 m. Since trawling effort dur- ing U.S. spring and fall surveys was proportional to the area of each depth interval (Table 3), the number of shad catches within these depth strata was amenable to chi-square analysis. A compari- son between shad catches at each depth interval and catches at all other depths combined indicated 105 125 145 Median Deplhlmt FIi;lirE 4. — Frequency of American shad catches with depth at 527 survey stations. 1963-76. Cape Hatteras, N.C., to Nova Scotia. T.'iBLE 3. — Depth intervals within the survey area and as- sociated shad catches during U.S. bottom trawl surveys. 1967- 76. Cape Hatteras. N.C., to Nova Scotia. Depth interval (m) Survey area Numt^er of trawls with shad km^ % Observed Expected k' 27-55 56-110 111-185 186-366 Totals 47,412 254 55,009 29 5 53,769 28 9 30,181 16,2 186,391 100-0 45 109 53 23 230 58 68 67 37 230 389- 35 10-- 4 13- 6 32- •P--0.05. ••P 01, that the greater capture frequency in the 56- 110 m interval was highly significant (P<0.01); shad catches at all other depths were significantly fewer (P<0.05) than expected (Table 3). Spring surveys were conducted mainly in March and April, accounting in part for the more fre- quent collections during these 2 mo (Figure 5). In March, shad were distributed along the Middle Atlantic Bight. Most fish between Long Island, N.Y., and Cape Cod, Mass., were taken in 60-200 m of water, many along the outer continental shelf (Figure 5). Few shad occurred in <60 m of water north of lat. 40°N, whereas most catches south of Long Island were at depths <60 m. During the summer, shad were not captured south of lat. 40'N (Figure 6). Forty-six collections in July and August were made in two general areas: the Gulf of Maine and southeast of Cape Cod, near Nantucket Shoals. Mean depth at these stations was 95 m, but ranged from 35 to 214 m. Catches were distributed along the coastal margin of the Gulf of Maine and the southern half of Georges Bank; most trawling stations in the deeper, central Gulf did not collect shad. October received the greatest trawling effort during autumn surveys. Shad were again distrib- 202 NEVES and DESPRES: OCEANIC MIGRATION OF AMERICAN SHAD Figure 5. — Location of all American shad catches during spring bottom trawl surveys, 1968-76, Cape Hatteras, N C, to Nova Scotia. ^v'- -200 ^., ^ Georges i' ''■*♦*# Bank,'' ■at ■' '*i ,' E : o Spring :8 • March April • May \ ""^f \CQpe ] /Hatteras •P" -^^ 5. 203 FISHERY BULLETIN: VOL. 77. NO, 1 %-J y.v Seolia J : I ..■■■ ; :. ' .-S v;r :. j/h. I:-' ^t;-^' I \ : ^- .,' Gull of Moine. . ^* 200 Ik- • Georges » * -fc^ If* • 1^ Sf I'; S:. * Summer • Winter V ' .Cope 'HoMeras FIGI'RE 6 — Location of all American shad catches during sum- mer and winter bottom trawl surveys, 1963-76, Cape Hatteras. N.C., to Nova Scotia. uted along the Gulf of Maine and Georges Bank perimeter, as well as south of Nantucket Shoals (Figure 7). Most of these captures were along the continental shelf at depths of >60 m. Monthly catches indicated a southward movement out of the Gulf of Maine in late autumn, although some shad remained there into November. During lOyr of autumn bottom trawl surveys along the Middle 204 Atlantic States, shad were never collected offshore south of lat. 39°N. The relatively low number of successful trawl- ing stations during the winter may be inadequate to define the southern limit of the wintering area (Figure 6). Winter catches occurred at 22 stations from southern Long Island (lat. 39°N) to the southern edge of Georges Bank (lat. 41''N) and reflected the same general area where shad began congregating in autumn ( Figure 7). Except for two shallow-water stations, winter collections of shad were made at a mean depth of 108 m. DISTRIBUTION OF INTERNATIONAL CATCHES The season for major shad catches in ICNAF divisions (Figure 8) agreed closely with distribu- tion according to bottom trawl surveys. Largest annual catches were reported by the United States in Subarea 6 ( 1,517-2,812 1). United States catches between 1970 and 1976 occurred primarily in Di- vision 6B and ranged from 112 to 1,272 t in March and April. Most of this spring catch was taken by the inshore commercial fishery. The only other catch of comparable size was made in Division 5Ze by the Federal Republic of Germany during Sep- tember 1973 and totaled 302 t. Catches in Subarea 5 occurred mainly in autumn; however, winter catches were reported in Division 5Zw and 6A between New Jersey and Cape Cod. Canadian catches in Subarea 4 were greatest in May, with decreasing catches throughout the summer. DISCUSSION The sampling design of NMFS bottom trawl surveys covers a large area in a relatively short period of time and provides good data on fish dis- tribution and concurrent environmental condi- tions. Even though these surveys were initially designed to sample primarily demersal species, results do reflect major changes in the abundance of pelagic species as well (Schumacher and An- thony'; Anderson*). Bottom trawls used during U.S. surveys are less effective on A/osa spp. than 'Schumacher, A., and V. C. Anthony. 1972. Georges Bank (ICNAF Division 5Z and Subarea 6) herring assessment. Int. Comm. Northwest Atl, Fish. Anna. Meet. 1972. Res. Doc. No. 24, Serial No. 2715. 36 p. "Anderson, E. D. 1973. Assessmentof Atlantic mackerel in ICNAF Subarea 5 and Statistical Area 6. Int. Comm. North- west Atl. Fish. Annu. Meet. 1973. Res. Doc. No. 14. Serial No. 2916, 37 p. NEVES and DEPRES, OCEANIC MIGRATION OF AMERICAN SHAD Figure 7. — Location of all American shad catches during autumn bottom trawl surveys, 1963-76, Cape Hatteras, N.C, to Nova Scotia. r^-; / Nova Scott ]i "x :S"' o o , ,. V ' f 1 ^ O Gulf of Maine ;*V;:-200' ; .* - '.; ,' ■,■ * •.*■*. '■ii -J :L* _ • •' * ;■ ^ Georges v '■■^. Bank ' : it/* •:• /V " September * October • November '■^\\ ON •O Cape /Hatteras ^ ^1 -^A^-*^, 205 FISHHRV Hl'LI.ETIN V(1L 77. NO 1 TW ^ \ \ i \ ^ -^iv^ .^ \.y 1 :/ M-^\y f 1 \ #r^^ \ M/^^ ^ :-'^"^' Figure 8. — Seasonal distribution of major American shad catches in the International Commission for the Northwest At- lantic Fisheries divisions. 1970-75, Cape Hatteras. N.C., toNova Scotia. foreign midwater trawls or the wing trawl (Hol- land**), but bottom trawl survey data provide the most complete, available records on offshore oc- currence. Based on the data presented, survey-related ob- servations to be discussed, and literature to be reviewed, we propose the following migratory cycle for American shad. Offshore movements are 'Holland. B. F., Jr. 1975 Anadromous fisheries research program, northern coastal area. Section 11. N.C. Proj. AFCS ll-lJob6, 43p limited to areas and depths with near-bottom temperatures between 3° and 15°C. Shad occur most frequently in offshore areas of intermediate depths (appro.ximately 50-100 m). Adults that survive spawning together with subadults mi- grate to the Gulf of Maine or to an area south of Nantucket Shoals and remain there through the summer and early autumn. During this period of active feeding, shad are vertical migrators and follow the diel movements of zooplankton in the water column. Most shad move out of the Gulf of Maine in autumn with declining water tempera- tures and congregate offshore, between southern Long Island and Nantucket shoals (lat. .39"-4rN) during the winter. Adults enter coastal waters in a broad front toward the Middle Atlantic coast, as far south as North Carolina during the winter and spring. Shad populations returning to South At- lantic rivers migrate south adjacent to the coast and within the 15°C isotherm to reach home rivers by winter and early spring. North Atlantic popu- lations proceed north up the coast in the spring with the warming of coastal waters above 3°C. Offshore Distribution The wide range of surface temperatures at sta- tions where shad were caught does not support the e.xtrapolation of the inshore temperatures-shad migration regime proposed by Leggett and Whit- ney (1972) to explain offshore movements. The influence of temperature on fish behavior and physiology is most pronounced during the spawn- ing season (Laevastu and Hela 19701, particularly for anadromous fishes. Tag returns within the 13°-18°C isotherms (Leggett and Whitney 1972) may have reflected inshore physiological changes in prespawning adults, leading to higher optimal temperatures approaching those for spawning. Our results indicate that near-bottom tempera- tures between 3' and 15°C provide a better basis for predicting shad movements in offshore waters. Offshore catches during NMFS surveys re- vealed that shad are not limited to the Gulf of Maine in summer months as reported by Talbot and Sykes ( 1958). Shad were also collected in an area south of Nantucket Shoals during summer and autumn surveys. Although shad from most river systems have been collected in the Gulf of Maine during the summer (Talbot and Sykes 1958), it is not known whether all populations migrate together at sea. Distribution during the spring is widespread and not indicative of a syn- 206 NEVES and DESPRES OCEANIC MIGRATION OF AMERICAN SHAD chronous species migration as suggested by Leggett (1977). Coastal tagging studies during the spring reveal an aggregation of many spawning stocks that often detour into estuaries along the coast (Sykes and Talbot 1958; Talbot and Sykes 1958; Chittenden 1974; Leggett 1977; White et al.'"). However, the length oftime each population has been inshore is unknown. Until stock iden- tification at sea is feasible, the regional composi- tion and extent of offshore mixing cannot be documented. The location of winter collections (lat. 39°-41°N) coincides with two previously published capture records (Talbot and Sykes 1958; Walburg and Nichols 1967), but the extent of overwintering in deep water off the continental shelf is unknown. Shad collections in the northern Gulf of Maine during November and December were made at depths >100 m and do not conform (based on pre- vious studies) with the expected migration south in late autumn. These and other shad captured in deep water near Nova Scotia during March fVla- dykov 1936) are outside the apparent wintering area, south of Nantucket Shoals. The possibility that some shad overwinter or become thermally isolated in deepwater areas off Nova Scotia (Vla- dykov 1936; Hodder 1966) needs further investi- gation. Circulation patterns along the Atlantic coast do not account for the seasonal distribution of shad according to survey data or their coastal migration routes based on tagging studies (Talbot and Sykes 1958; Leggett 1977). Bottom drift toward shore and coastal drift south in the Middle Atlantic Bight during winter (Bumpus 1973) would aid migrants moving south, but seasonal shifts in di- rectional flow along the east coast and their effect on shad movements are liable to subjective in- terpretation. Spawning populations moving north and south concurrently could be helped or hin- dered by circulation patterns in the mid-Atlantic area. We believe that seasonal shifts in isotherms, as influenced by circulation patterns, are of great- er importance in defining the migratory route of shad. tribution in the water column from three separate sources: food habits, diel differences in catchabil- ity, and effectiveness of various trawls in captur- ing shad. Adult shad are zooplankton feeders and consume primarily large copepods, mysids, and euphausiids (Bigelow and Schroeder 1953; Hil- debrand 1963; Leim and Scott 1966). The con- sumption of food organisms such as mysids and zoobenthos indicates that part of a shad's life is spent near the ocean bottom (Leim 1924; Walburg and Nichols 1967). In general, stomach analyses reveal that shad feed at all depths but particularly where concentrations of zooplankton occur. Trawling stations where shad were collected during U.S. surveys ( 24 h/day) were partitioned by capture time (Eastern Standard Time) into day (0600-1800 h) and night ( 1800-0600 h). Chi-square analysis on time of capture revealed that daytime catches occurred significantly more often (P<0.01) than night collections (Table 4). Of the night catches, 25'^f occurred within 1 h of the daytime interval. Shad were apparently closer to the bot- tom during daylight hours and thus more suscep- tible to bottom trawling gear. Further corrobo- ration of this daytime occurrence nearer to the bottom is evidenced by the frequency of shad catches in foreign bottom trawls. During daylight hours in March 1974-76, foreign research vessels used herring trawls to sample 280 stations from Long Island to Georges Bank and recorded shad at 71 (25'/( ) of these stations. Contemporary surveys by the United States in the same area with the No. 41 Yankee trawl sampled 207 daytime stations and collected shad at 22 ( ll'/f ) of them. Maximum headrope distance off the bottom for the U.S. trawl was 5 m. The larger foreign trawls had a higher opening (6 m) which increased their effectiveness on off-bottom species, although extra-trawl factors such as vessel size, speed, and gear rigging cer- tainly contributed to the greater overall fishing power of these trawls (Grosslein 1969, 1971). We deduce from the above observations that shad are vertical migrators like other schooling planktivores such as herring, Cliipea harengus, and mackerel. Scomber scombrus (Blaxter 1975; Vertical Distribution Presently there is little information on the depths preferred by shad at sea. We inferred dis- '»White,R.L.,J. T.Lane, and P.E.Hamer. 1969. Popula- tion and migration study of major anadromous fish, N.J, Div. Fish Game Misc. Rep. No. 3M, 21 p. Table 4, — Chi-square test comparing the number of day and night catches of shad during U.S. bottom trawl surveys. 1963-76, Cape Hatteras, N.C. to Nova Scotia. Time Day (0600-1800 h) Nighl (1800-0600 h) Totals ••p. 001 Observed 217 98 Expected 1575 157 5 207 FISHERY BULLETIN VOL 77. NO 1 Isakov"; Rikhter'^), following the diel movements of zooplankton in the water column. This reliance on zooplankton for food may be an additional fac- tor influencing shad distribution during the year. Zooplankton distribution in the Gulf of Maine dur- ing summer and autumn is closely tied to local and regional hydrography (Redfield 1941; Sherman 1966; Cohen'-''); concentrations generally occur along areas of current convergence and divergence (Zinkevich 1967) and at depths <100 m (Bigelow 1926; Whiteley 1948). During winter, the waters around Georges Bank are nearly devoid of zoo- plankton, whereas sizeable neritic populations occur from Nantucket Shoals to southern Long Island (Clarke 1940; Grice and Hart 1962; Zin- kevich 1967). Sette (1950) concluded that water temperature had a limiting rather than causal influence on the seasonal movements of mackerel, and Redfield (1941) noted a parallelism between mackerel distribution and areas of zooplankton abundance. Similarly, Zinkevich (1967) related herring movements to water temperature and seasonal shifts in zooplankton concentrations. Catches of shad during bottom trawl surveys along Georges Bank, Gulfof Maine perimeter, and south of Nantucket Shoals may therefore be re- lated to zooplankton abundance in these areas, but direct evidence is lacking. Coastal Migration Tagging studies and the location of NMFS and ICNAF catches during the spring indicate that most shad populations move toward the mid- Atlantic coast from offshore waters, between lat. 36° and 40°N in the winter and early spring. The time an4 location of tag returns by the mid- Atlantic shad fishery demonstrate that shad from most populations occur in this region during the spring (Talbot 1954; Talbot and Sykes 1958; Leggett 1977; White et al. see footnote 10). Shad tagged near southern Long Island in early spring were recaptured on spawning runs as far south as North Carolina (Talbot and Sykes 1958). Tagging "Isakov, V. I, 1976. The peculiarities of diurnal vertical migrations of mackerel in the northwestern Atlantic. Int. Comm. Northwest Atl. Fish. Annu. Meet. 1976, Res. Doc. No. lll.Senal No. 3934. 3 p. '^Rikhter, V. A. 1976. Proposal on trawUng surveys for estimation of pelagic fish stocks in ICNAF Subarea 5 and Statis- tical Area 6. Int. Comm, Northwest Atl. Fish, Annu. Meet, 1976, Res, Doc, No, 116. Serial No, 3939, 3 p, ^•*Cohen, E, B, 1975, An overview of the plankton com- munitiesof the Gulf of Maine, Int, Comm, Northwest Atl, Fish, Annu. Meet, 1975, Res. Doc, No, 106, Serial No, 3599, 16 p. of shad in North Atlantic rivers during the spawn- ing period produced recaptures as far south as the North Carolina coast in subsequent years (Talbot 1954; Vladykov 1956; Talbot and Sykes 1958; Leggett 1977). These tag returns provide an ap- proximate geographical range of entry into coastal waters by returning oceanic migrants (lat. 36°- 40°N). Assuming that the 3°and 15"C isotherms define the northern and southern limits respectively of shad movements at sea, prespawning adults re- turning to coastal waters from the ocean would face a thermal barrier south of Cape Hatteras. Offshore bottom temperatures along the South At- lantic coast remain above 17.5°C during the year, whereas bottom temperatures on the continental shelf north of Cape Hatteras and inshore tempera- tures for the South Atlantic coast drop below 15°C by December ( Figure 9). The proximity of the Gulf Stream to North Carolina creates a narrow coastal corridor at Cape Hatteras, providing the only mi- gratory route to southern rivers if shad returning to these home rivers are to remain within their marine temperature regime. Migration toward shore north of Cape Hatteras and then south along the coast appear to be essential prerequisites for successful homing to South Atlantic rivers. In con- trast, shad returning to North Atlantic rivers dur- ing the spring are not obliged to follow a coastal route because offshore temperatures in the Middle Atlantic Bight are well within the shad's range of oceanic occurrence (Figure 9). However, tag re- turns from adults tagged on spawning runs into North Atlantic rivers indicate that many (most?) adults do enter coastal waters in the lower mid- Atlantic region and migi'ate north along the coast to reach home rivers as repeat spawners the fol- lowingspring(Talbot 1954; Leggett 1977). Results of Atlantic coast tagging are consistent with our upper temperature limit ( 15°C) for shad migration at sea; all prespawning, oceanic migrants enter inshore waters as far south as North Carolina. The significance of the Cape Hatteras region to other aspects of northern versus southern shad biology was discussed by White and Chittenden ( 1977). Based on our proposed migratory route, large shad catches in ICNAF Division 6B during the spring would consist of shad entering home rivers and populations moving toward and along the coast. Catches in Chesapeake Bay and the sounds of North Carolina from late November to early December (Hildebrand and Schroeder 1928; Tal- bot and Sykes 1958; Walburg and Nichols 1967) 208 NEVES and DESPRES OCEANIC MIGRATION OF AMERICAN SHAD f- il NOVEMBER DECEMBER Figure 9. — Mean monthly bottom temperatures dunng winter and spring along the eastern U.S. coast. Cape Cod. Mass.. to Florida. (From Walford and Wicklund 1968.) would be shad returning to natal rivers farther south. Inshore temperatures are unstratified along the Atlantic coast during the winter (Parr 1933). Since freshwater discharge generally oc- curs along the surface from estuaries, water tem- peratures would not preclude near-surface move- ments of shad to detect essential olfactory and rheotaxic cues for successful homing (Dodson and Leggett 1974). Estuarine temperatures from initial to peak ar- rival of shad at home rivers along the Atlantic coast are between 3° and 15°C (Talbot 1954; Massmann and Pacheco 1957; Walburg and Nichols 1967; Leggett 1972; Leggett and Whitney 209 FISHERY BULLETIN VOL 77. NO 1 1972; Chittenden 1976; Sholar'^). Within this temperature regime, southern populations begin reaching home estuaries at the higher tempera- tures, while northern populations do so at the lower temperatures. Peak numbers of shad enter the St. Johns River, Fla., in mid-January when water temperatures are at an annual low of 15°C; the peak in juvenile emigration occurs simultane- ously (Leggett and Whitney 1972; Williams and Bruger 1972). Shad first enter the Connecticut River in late March-early April when water tem- peratures are approximately 4°C and peak in abundance at 13°C (Leggett and Whitney 1972). In general, most shad populations north ofCapeHat- teras begin entering rivers at approximately 4°C, and the peak in upstream migration occurs at temperatures between 10° and 15°C (Leggett and Whitney 1972). The lower thermal tolerance of juvenile shad in freshwater was near 2.2°C in a short-term laboratory .*udy (Chittenden 1972) and roughly 3°-4°C in small ^jutdoor ponds (Blair'^). This lower thermal limit agrees closely with the lowest tem- perature at which subadult shad were collected during NMFS offshore surveys (3°C). Chittenden (1972) also reported that juveniles ceased feeding when water temperatures dropped below 4.4°C. However, we collected 17 juvenile and subadult shad (9-32 cm FL) during a NMFS coastal survey in January 1978, at stations with bottom tempera- tures between 2.8° and 4.3°C. All but one stomach were filled with mysids and copepods, indicating active feeding at these temperatures in saltwater. Further evidence to support our bottom temper- ature regime for predicting the coastal movements of shad is provided by North Carolina's anadro- mous fishery research program. Their annual sur- veys on river herring since 1971 show that shad occur off the North Carolina coast from January to April, at bottom temperatures between 6° and 12°C and at depths <26 m (Johnson et al."*). Shad catches decline substantially when water temper- atures exceed 12°C, coinciding with entry into es- tuaries or possibly, northward migration. This '^Sholar, T. M. 1977. Anadromous fisheries research pro- gram. Cape Fear River System, phase 1. N.C. Proj. AFCS 12.6.3 p. '^Blair, A. B. 1977. American shad culture and distribu- tion studies at Harrison Lake National Fish Hatchery. Proc. Workshop American Shad, Amherst, Mass., Dec. 1976, 10 p. ">Johnson. H. B.. B. F. Holland, Jr., and S G Keefe. 1977. Anadromous fisheries research program, north- em coastal area. Section II. N.C. Proj. AFCS 11-2, 41 p. temperature range concurs with offshore bottom temperatures having the most frequent shad catches during NMFS bottom trawl surveys (7°- 13°C). The shallow depths traveled by coastal migrants during the winter and spring would ac- count for their unavailability to offshore sam- pling. Critical data on the oceanic phase of most anad- romous fishes are lacking (Harden-Jones 1968), and our general description of shad movements must await additional research at sea to corrobo- rate or correct the proposed migratory cycle. It would seem energetically wasteful for North At- lantic populations to follow the same shoreward route as do Middle and South Atlantic shad. The return of all populations to this region may have historical significance, since shad are believed to have been most abundant in the mid-Atlantic por- tion of their coastal range (Leim 1924). Variations in life history patterns among populations are generally considered to be adaptive responses (Cole 1954; Murphy 1968; Gadgil and Bossert 1970), and differences in life history characteris- tics among shad populations in rivers ( Carscadden and Leggett 1975b) may also exist at sea. Endocrine-induced differences in the timing of migratory behavior and gonadal maturation may be life history strategies of adaptive significance, considering the species' wide geographical range (21° of latitude). The lengthy period of migration toward the mid-Atlantic coast from offshore by prespawning adults may stem from population- specific responses to photoperiod or temperature cues. Further study on the sensory systems and environmental cues involved in migration is re- quired before a more comprehensive explanation for the migratory cycle of shad is available. ACKNOWLEDGMENTS We are indebted to the Resource Surveys Inves- tigation section and other staff members at NMFS, Woods Hole, for their cooperation in this endeavor. Special thanks go to Ralph Mayo for sharing his computer expertise and to Bill Leggett, Emory Anderson, Jon Gibson, Brad Brown, and an anonymous reviewer for reviewing the manuscript. The Massachusetts and Virginia Cooperative Fishery Research Units provided financial support. We dedicate this paper to R. J. Reed for his contributions to the study of Ameri- can shad biology. 210 NEVES and DEPRES OCEANIC MIGRATION OF AMERICAN SHAD LITERATURE CITED BIGELOW. H. B. 1926. Plankton of the offshore waters of the Gulf of Maine. Bull. U.S. Bur. Fish. 40. 509 p. BIGELOW, H. B., AND W. C. SCHROEDER 1953. Fishes of the Gulf of Maine. U.S. Fish Wildl. Serv., Fish. Bull. 53, 577 p. BLAXTER. J. H. S. 1975. The role of light in the vertical migration of fish - a review. In G. C. Evans, R. Bainbridge. and O. Rackham (editors). Light as an ecological factor II, p. 189-210. Black well Sci. Publ., Oxf. BUMPUS. D. F. 1973. A description of the circulation on the continental shelf of the east coast of the United States. Prog. Oceanogr. 6:111-157. BUMPUS. D. F., AND L. M. LAUZIER. 1965. Surface circulation on the continental shelf off east- em North America between Newfoundland and Flori- da. Ser. Atlas Mar. Environ.. Am. Geogr. Soc. Folio 7. CARSCADDEN. J. E., AND W. C. LEGGETT 1975a. Meristic differences in spawning populations of American shad, A/osa sapidissima: evidence for homing to tributaries in the St. John River, New Brunswick. J. Fish. Res. Board Can. 32:653-660. 1975b. Life history variations in populations of American shad, A/osa sapidissima (Wilson), spawning in tributaries of the St. John River, New Brunswick. J. Fish Biol. 7:595-609. CHEEK, R. P. 1968. The American shad. U.S. Fish Wildl. Serv., Fish. Lean. 614, 13 p. Chittenden, M, E.. Jr. 1969. Life history and ecology of the American shad, A/osa sapidissima, in the Delaware River. Ph.D. Thesis, Rut- gers Univ., New Brunswick, N.J., 459 p. 1972. Responses of young American shad, Alosa sapidis- sima, to low temperatures. Trans. Am. Fish. Soc. 101:680-685. 1974. Trends in the abundance of American shad, Alosa sapidissima, in the Delaware River Basin. Chesapeake Sci. 15:96-103. 1975. Dynamics of American shad, Alosa sapidissima, runs in the Delaware River. Fish. Bull., U.S. 73:487- 494 1976. Present and historical spawning grounds and nur- series of American shad,.4/osa sapidissima, in the Dela- ware River. Fish. Bull., U.S. 74:343-352. CHURGIN, J„ AND S. J. HALMINSKI 1974. Temperature, salinity, oxygen, and phosphate in waters off United States. NOAA Key to Oceanographic Records, Doc. No. 2:1-166. Clarke, G. L. 1940. Comparative richness of zobplankton in coastal and offshore areas of the Atlantic. Biol. Bull. (Woods Hole) 78:226-255. COLE. L. C. 1954. The population consequences of life history phenomena. Q. Rev Biol. 29:103-137. COLTON. J. B., JR , AND R. R. STODDARD 1972. Average monthly sea-water temperatures. Nova Scotia to Long Island, 1940-1959. Ser. Atlas Mar. Envi- ron., Am. Geogr, Soc, Folio 21. DODSON. J. J., AND W. C. LEGGETT. 1974. Role of olfaction and vision in the behavior of Ameri- can shad [Alosa sapidissima) homing to the Connecticut River from Long Island Sound. J. Fish. Res. Board Can. 31:1607-1619. GADGIL, M., AND W. H. BCSSERT. 1970. Life historical consequences of natural selec- tion. Am. Nat. 104:1-24. Grice, G. D., and a. D. Hart 1962. The abundance, seasonal occurrence and distribu- tion of the epizooplankton between New York and Ber- muda. Ecol. Monogr. 32:287-307. GROSSLEIN. M. D. 1969. Groundfish survey program of BCF Woods Hole. Commer. Fish. Rev. 31(8-9):22-35, 197 1 . Some observations on accuracy of abundance indices derived from research vessel surveys. Int. Comm. Northwest Atl. Fish., Redb. Part 111:249-266. Harden-Jones, F. R. 1968. Fish migration. E. Arnold Publ, Lend, 325 p. Hildebrand, S. F, 1963- Family Clupeidae, /n Fishes of the western North Atlantic, part three, p. 257-454. Mem. Sears Found. Mar. Res. Yale Univ. 1. Hildebrand. S. F., and W. C. Schroeder 1928. Fishes of Chesapeake Bay. Bull. U.S. Bur. Fish. 43, 366 p. HILL, D, R. 1959. Some uses of statistical analysis in classifying races of American shad [Alosa sapidissima). U.S. Fish Wildl. Serv.. Fish. Bull. 59:269-286, HODDER, V. M. 1966. Two further records of the American shad in New- foundland waters. Trans. Am. Fish. Soc. 95:228-229. HOLLIS, E. H. 1948. The homing tendency of shad. Science (Wash.. D.C.) 108:332-333. LAEVA.STU, T., AND I. HELA 1970. Fisheries oceanography. Fishing News (Books) Ltd., Lond., 238 p. LE(3GETT, W. C. 1969. Studies of the reproductive biology of the American shad LAlosa sapidissima, Wilson). A comparison of popu- lations from four rivers of the Atlantic seaboard. Ph,D. Thesis, McGill Univ., Montreal, 125 p. 1972. Weight loss in American shad LAlosa sapidissima, Wilson I during the freshwater migration. Trans. Am. Fish, Soc. 101:549-552. 1973. The migrations of the shad. Sci. Am. 228(31:92-98. 1977. Ocean migration rates of American shad lAlosa sapidissima). J. Fish. Res. Board Can. 34:1422-1426. LEGGETT. W. C, AND R. R. WHITNEY 1972. Water temperature and the migrations of American shad. Fish. Bull.. U.S. 70:659-670. Leim. a. H. 1924. The life-history of the shad (A/osa sapidissima (Wil- son)) with special reference to the factors limiting its abundance. Contrib. Can. Biol.. New Ser,. 2:161-284. Leim. a. H.. and W. B. Scott. 1966. Fishesof the Atlantic Coast of Canada. Fish. Res. Board Can. Bull. 155. 485 p. MA.SSMANN. W. H.. AND A. L. PACHECO 1957. Shad catches and water temperatures in Vir- ginia. J. Wildl. Manage. 21:351-352. 211 FISHERY BULLETIN VOL 77. NO 1 Murphy, G. I. 1968. Pattern in life history and the environment. Am. Nat. 102:391-403. Nichols, p. R. I960. Homing tendency of American shad, Alosa sapidis- sima, in the York River, Virginia. Chesapeake Sci, 1:200-201 1 966. Comparative study of juvenile American shad popu- lations by fin ray and scute counts. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 525, 10 p. Parr. a. E. 1933. A geographic-ecological analysis of the seasonal changes in temperature conditions in shallow water along the Atlantic coast of the United States. Bull. Bingham Oceanogr. Collect. Yale Univ. 4l3), 90 p REDFIELD. A. C. 1941- The effect of the circulation of water on the distribu- tion of the calanoid community in the Gulf of Maine. Biol. Bull. (Woods Hole) 80:86-110. SETTE. O. E. 1950. Biology of the Atlantic mackerel iScomber scorn- brus) of North America. Part II. Migrations and habits. U.S. Fish Wildl. Serv., Fish. Bull. 51:251-358. Sherman. K. 1966. Seasonal and areal distribution of zooplankton in coastal waters of the Gulf of Maine, 1964. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 530, 11 p. STOMMEL, H. 1965. The Gulf Stream. Univ. Calif. Press, Berkeley, 248 p. Sykes. J. E., AND G. B. Talbot 1958. Progress in Atlantic coast shad investigations - mi- gration. Proc.Gulf Caribb. Fish. Inst., 11th Annu. Sess., p. 82-90. Talbot. G. B. 1954. Factors associated with fluctuations in abundanceof Hudson River shad. U.S. Fish Wildl. Serv., Fish Bull. 56:373-413. Talbot. G. B., and J. E. Sykes. 1958. Atlantic coast migrations of American shad. U.S. Fish Wildl. Serv., Fish. Bull. 58:473-490. Vladykov. v. d. 1936. Occurrence of three species of anadromous fishes on the Nova Scotian Banks during 1935 and 1936. Copeia 1936:168. 1950. Movements of Quebec shad {Aiosa sapidissima) as demonstrated by tagging. Nat. Can (Que.) 77:121-135. 1956. Distant recaptures of shad iAlosa sapidissimai tag- ged in Quebec. Nat. Can. (Que.) 83:235-249. Walburg. C. H. 1960. Abundance and life history of the shad, St. Johns River, Florida. Fish Bull., U.S. 60:487-501 Walburg, C. H., and p. r. nichoi^ 1967. Biology and management of the American shad and status of the fisheries, Atlantic coast of the United States, 1960. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 550, 105 p. WALFORD. L. a., and R. I. WICKLUND 1 968. Monthly sea temperature structure from the Florida Keys to Cape Cod. Ser. Atlas Mar. Environ., Am. Geogr. Soc. Folio 15. White. M. L., and M. E. Chittenden. Jr 1977. Age determination, reproduction, and population dynamics of the Atlantic croaker, Micropogonias un- dulatus- Fish. Bull., U.S. 75:109-123. WHITELEY. G. C, Jr 1948. The distribution of larger planktonic Crustacea on Georges Bank. Ecol Monogr 18:233-264. Williams. R. O., and G. E. Bruger 1972. Investigations on American shad in the St. Johns River. Fla. Dep. Nat. Resour. Tech. Ser. 66, 49 p. ZINKEVICH. V. N. 1967. Observations on the distribution of herring. Clupea harengus L., on Georges Bank and in adjacent waters in 1962-65. Int. Comm. Northwest Atl. Fish., Res. Bull. 4:101-115. 212 SOURCES AND DISTRIBUTION OF BLUEFISH, POMATOMUS SALTATRIX, LARVAE AND JUVENILES OFF THE EAST COAST OF THE UNITED STATES Arthur W. Kendall. Jr.' and Lionel A. Walford^ ABSTRACT Larval bluefish are found offshore somewhere between Cape Cod, Mass. , and Palm Beach, Fla. , dunng every season of the year. However, there appear to be two main spawning concentrations — one during spring near the western edge of the Gulf Stream in the South Atlantic Bight and the other during summer over the contmental shelf of the Middle Atlantic Bight. Larvae complete development near the surface; juveniles are strongly associated with the surface. Juveniles from the spring spawning remain at sea and are carried northward past Cape Hatteras, N.C., above the edge of the continental shelf As surface shelf water warms, they move shoreward to spend the summer in estuaries of the Middle Atlantic Bight Bluefish spawned in summer remain at sea asjuveniles or enter estuaries briefly in late summer. In fall, as the water cools, the juveniles move southward out of the Middle Atlantic Bight. It is possible that these two spawnings represent different populations. A smaller fall and winter spawning which occurs offshore south of Cape Hatteras may represent a small population resident to the South Atlantic Bight. Bluefish, Pomatomus saltatrix (Linnaeus), occur in most temperate coastal regions of all world oceans (Briggs 1960). Fowler (1944) erroneously reporteii them from the eastern Pacific where they do not occur. The earliest descriptions of eggs and larvae of bluefish by Agassiz and Whitman ( 1885) which have been quoted by other authors, e.g., Padoa (1956) and Salekhova (1959), are errone- ous. Colton and Honey (1963), Deuel et al. ( 1966). and Norcross et al . ( 1 974 ) correctly described them and showed that bluefish spawn pelagic eggs in the open sea and larval development takes place near the surface. Juveniles generally move from the open sea to coastal areas and estuaries. This pattern has been observed off North .'\merica. in the Black Sea. and off South Africa (Irvme 1947; Bigelow and Schroeder 1953; Oben 1957; Smith 1961). Along the Middle Atlantic Bight, i.e., from Cape Cod, Mass., to Cape Hatteras, N.C., bluefish eggs, larvae, and juveniles have been collected during several ichthyoplankton studies (Sette 1943; Lund and Maltezos 1970; Norcross et al. 1974). Al- though restricted in sampling area or time, these 'Northeast Fisheries Center Sandy Hook Laboratory, Na- tional Marine Fisheries Service, NOAA. Highlands, NJ 07732; present address; Northwest and Alaska Fisheries Center, NMFS, NOAA, 2725 Montlake Boulevard East, Seattle. WA 98112. ^New Jersev Marine Sciences Consortium, Fort Hancock, N.J 07732. studies have indicated that spawning and larval development take place offshore from Chesapeake Bay to southern New England in late spring and summer. Juveniles occur in estuaries along the middle Atlantic coast in summer (Clark^). The sources of data for this paper are plankton collections taken by personnel of the National Marine Fisheries Service (NMFS), NOAA, Sandy Hook Laboratory, as part of a study to investigate the importance of estuaries as nursery areas of Atlantic coast fishes. The first part of this study consisted of a survey of ichthyoplankton over the continental shelf an area thought to be the spawn- ing grounds for many species of fishes. From in- formation gained during this study, we hoped to trace the movement of young stages from spawn- ing grounds and thus evaluate the importance of estuaries as nurseries. From the results of this study, several additional short cruises were con- ducted to study further the distribution of larval and juvenile bluefish in certain offshore areas at specific times of the year. In this paper, information from these studies and those of previous workers is presented to help elucidate the times and places of bluefish spawn- M.tnuscript accepted September 197H FISHERY BULLETIN: VOL 77. NO 1. 1979 =Clark, J, R, 1973. Bluefish. In A. L. Pacheco (editor). Proceedings of a workshop on egg, larval, and juvenile stages of fish in Atlantic coast estuaries, p. 250-251. Middle Atl, Coastal Fish. Cent,. Tech. Publ. 1. 213 FISHERY BinXETIN VOL 77, NO 1 ing along the east coast. Evidence to link the MATERIALS AND METHODS offshore occurrences of bluefish larvae to the es- tuarine occurrences of bluefish juveniles also is (Table 1, Figure 1) presented. This early life history information re- lates to what is known of the number and relative An ichthyoplankton study of Atlantic continen- sizes of populations of bluefish along the east tal shelf waters by the Sandy Hook Laboratory coast. began in 1965-66 with a survey from Cape Cod to T.-\BLE 1.— Bluefish collections 1 from RV Dolphin ichthyoplankton surv ■eys and supplemental cruises for young bluefish off the east coast of the United States. Number of Bluefish Number of Standard Continental shelf area Dates stations Gear' collections Number lengths (mm) Cape Cod to Cape Lookout 3-15 Dec 1965 78 35 Gulf V MV\n" 25 Jan.-9 Feb 1966 86 Gulf V MWT 1 1 8.7 6-22 Apr, 1966 92 3 Gulf V MWT 12-24 May 1966 92 63 Gulf V MWT 5 25 3 4-9 1 17-29 June 1966 92 Gulf V 59 MWT 2 2 33-37 5-26 Aug 1966 92 Gull V 25 1,621 2 4-13.2 66 MWT 4 8 9-128 13-18 Sept 1966 30 15 Gulf V MWT 2 2 4 0-6 7 28 Sept -20 Oct 1966 92 Gull V 1 2 3 3-4 77 MWT 1 17 26-219 9 Nov -4 Dec 1966 92 Gull V 68 MWT 2 2 49-124 New River. N C . to 15-19 Feb 1966 26 Gulf V 1 1 80 Palm Beach, Fla 7-15 May 1967 80 Gulf V 20 563 2 2-116 80 SMN 11 14 18-34 80 2-m ring 22 July-1 Aug 1967 80 80 53 Gull V SMN MWT 19-26 Oct 1967 80 80 77 Gulf V SMN 3-m ring 5 17 3 9-6 9 27 Jan -4 Feb 1968 80 80 Gull V SMN 2 2 5 1-6,0 50 MWT 2 5 63-92 New York Bight 10-16 June 1969 44 46 15 SMN MWT Nighllighl 1 1 1 1 45 1 45,9 15-18 June 1970 44 44 SMN 2-m ring 3 1 3 1 20 8-35 31 3 New Jersey to Maryland 14-18 June 1971 32 SMN 5 8 238-33.7 32 Haedrich 5 7 23,6-32 1 12 MWT 3 3 27,3-357 Virginia to North Carolina 27 Apr -5 May 1971 58 SMN 19 163 12 6-31 4 60 Haedrich 27 1.464 3 9-33,5 19 2-m ring 3 10 4 1-11,3 Cape Hatteras. N C. weekly. 1 1 Apr -31 May 1972 36 Haedrich 21 1.472 3 5-25 4 New Jersey to Virginia 29 Oct-1 Nov 1970 35 SMN 3 3 400-482 35 Haedrich 3 4 36,4-34,9 11 2-m ring 1 3 200 Georgia to Florida 29-31 Jan 1971 24 24 24 SMN Haedrich MWT 'MWT = midwater trawl; SMN = surface meter net, see text for further details 214 KENDALL and WALFORD SOIIRCES AND DLSTRIBl'TION OF BLUEFLSH MIDDLE > ATLANTIC BIGHT SOUTH ^ATLANTIC BIGHT PATHS 10 ^^ NUItSUBY FlGl!RE 1. — Major features of surface waters and bluefish larval and juvenile distribution off the U.S. east coast. Cape Lookout, N.C. Over the year, as weather permitted, 92 stations over 14 transects were sampled during 8 cruises. In 1967-68, the study continued, working from Cape Fear, N.C, to Palm Beach, Fla., sampling at 80 stations over 14 tran- sects during each of 4 seasonal cruises. Plankton was sampled with Gulf V samplers (0.52-mm mesh). The30-min step oblique tows were made at 2.1-2.6 m/s. Two nets were towed simultaneously; one from the surface to 15 m, the other from 18 to 33 m where water depths permitted. Details of gear, procedures, and physical, plankton volume, and juvenile fish data have been published (Clark et al. 1969, 1970). The same procedures were followed on two addi- tional cruises in 1966. One of these (D-66-2) sam- pled 26 stations on five transects between Jacksonville, Fla., and Palm Beach in February 1966. The other ( D-66-1 1 ) sampled 30 stations on the four northernmost transects (Cape Cod to New- Jersey) in September 1966. Collections for pelagicjuvenile fishes were made during the cruises in 1965-66 with a scaled-down Cobb midwater trawl (Clark et al. 1969). During the cruises in 1967-68, several nets were towed for juvenile fishes. At each station a surface meter net with 6-mm mesh was towed beside the ship. Sub- surface samplers included the scaled-down Cobb trawl, and a 1-m and a 2-m ring net (Clark et al. 1970). Several offshore cruises from 1969through 1971 were designed mainly to augment the data on oc- currences of bluefish juveniles. A surface meter net and a Haedrich neuston net (Bartlett and Haedrich 1968) were used in paired tows on most of these cruises. Other sampling equipment used at various times included dip nets with nightlights and several types of midwater nets. In spring 1972, a series of eight weekly cruises near Cape Hatteras aboard a chartered sport fishing boat was conducted working from Oregon Inlet, N.C, out into the Gulf Stream. On each cruise, we made two neuston tows with a Haedrich net near Cape Hatteras. One of these was in the green coastal water, the other in the blue Gulf Stream water, and each tow was within 100 m of the interface between the two water masses. Dur- ing the return to Oregon Inlet, some 60 km north of Diamond Shoals Light Tower, several addi- tional tows sampled the full range of surface water temperatures occurring in the area. Weather and water temperature data relative to these cruises were gathered from the U.S. Naval Oceanographic Office and the U.S. National Weather Service. Additional data on bluefish and juveniles and ancillary observations from these collections are available."* ■•Kendall, A. W.. Jr., and L. A. Walford. 1978. Data as- sociated with offshore larval and juvenile bluefish collections at Sandy Hook Laboratory 1965-1972. Unpubl. manuscr,, .5 p. Report No, SHL 78-9. Northeast Fisheries Center Sandy Hook Laboratory, National Marine Fisheries Service. NOAA, High- lands, NJ 07732. 215 FISHERY BULLETIN VOL 77. NO 1 We will generally refer to bluefish <10 mm standard length (SL) as larvae and those >10 mm SL as juveniles. Bluefish hatch at about 3 mm SL and by 10 mm SL the fin ray development is nearly complete and in living specimens the body is dark blue on the back and silvery on the sides, as in the pelagic juvenile stage of goatfish and mullet (Nor- cross et al. 1974). RESULTS H\dr<)graphiL Ffaturc!) iif Middle and South Atlantic Bights Shelf water characterized by salinities of <35%o, is divided into coastal water ( <33.6%o) and shelf edge water i33.6-35.0"'iMii i Wright and Parker 1976). The Gulf Stream, characterized by salinities "-36. 0"/oc) and/or temperatures -IS'C at 100 m or -IS'C at 200 m, flows generally beyond the edge of the continental shelf The water mass between the shelf water and Gulf Stream, called the slope water, is separated from the shelf water by a strong surface feature, except in midsummer, called the slope front. Surface manifestations such as lines of flotsam, differences in water color, and choppiness of the Gulf Stream are seen on moder- ately calm days. The .shelf water is sluggish and influenced by short-term effects of wind, but gen- erally moves south along the shore. The Gulf Stream moves northward or northeastward at ve- locities over 100 cm/s (Sverdrup et al. 1942). Eggs Bluefish eggs, which share features with pelagic eggs of many other species, were not found in any of our collections. Bluefish eggs have a smooth spherical membrane, a diameter of 0.90-1.20 mm averaging 1.00 mm, a pigmented yolk, a single oil globule about 0.2 mm in diameter, and melanophores in rows on the embryo (Deuel et al. 1966). Even though an egg has all of the above features, it can be identified with certainty as being a bluefish egg only if the oil globule is pig- mented and in later development the number of myomeres has become established at 24 to 28. Two studies have reported occurrences of bluefish eggs along the east coast. Marak and Col- ton (1961) listed a few of them from late May to early June 1953 in 12,8°C water south of Cape Cod. These data are suspect because: 1 ) identifica- tion was based on inadequate descriptions by Agassiz and Whitman (1885) and Perlmutter ( 1939); and 2) adult bluefish in spawning condition are not present off southern New England until later in the year when temperatures are consider- ably warmer. In a second study conducted from 1960 to 1962 off Virginia, Norcross et al. (1974) reported bluefish eggs during the period June through August from near shore to the continental slope. Although none occurred in our collections, from the similarity in distribution of bluefish eggs and larvae seen by Norcross et al. ( 1974), it seems that an accurate indication of spawning location can be derived from the capture of small larvae. Larvae .Scasonal-Cjfographic Distribution Although bluefish larvae occurred between Massachusetts and Florida during every season, two major geographically distinct concentrations of larvae were found; one south of Chesapeake Bay near the Gulf Stream in spring, and the other north of Cape Hatteras over the middle of the continental shelf in summer. During spring, bluefish larvae were taken from near Cape Hatteras to Cape Canaveral, Fla. Of the 473 larvae taken at 25 stations during the surveys of May 1966 and 1967, greatest concentrations were between the offings of New River, N.C., and Charleston, S.C., near the edge of the continental shelf (Figure 2). In April and May 1971, we also caught bluefish larvae near Cape Hatteras primarily offshore near the Gulf Stream. From these data, it appeared that bluefish spawned near the edge of the continental shelf in the South At- lantic Bight during spring. Bluefish dominated the neuston catches near Cape Hatteras during the eight weekly cruises in spring of 1972 (Table 2). They occurred on every cruise and in every water type sampled. The var- iability in catches between paired tows during this series was too large to permit precise comparison among the dates or sampling areas. However, the largest catches were made in water just shoreward of the Gulf Stream. Most of the specimens taken in or near the Gulf Stream were between 5 and 12 mm SL, whereas the few taken over the shelf ranged from 11 to 21 mm SL. The numbers of bluefish caught each week gave no indication of relative abundance during spring in this area, partially because weather-influenced 216 KENDALL and WALFORD SOURCES AND DISTRIBUTION OF BLUEFISH BLUEFISH LMVAE * -P CRUISf D -66 -S MAY 12-24, 1966 AA -PP; CRUISE 0-67-4 MAY 7 - 15, 1967 SELECTED SUFACE 1SOTHBMS ( "C 1 surface temperature patterns affected the catch rate. Large catches just shoreward of the Gulf Stream followed periods of northerly winds which caused a compression of surface isotherms in this area. Following southerly winds the isotherms were spread out and catches were low. It thus appears that the catch rate was related to the width of the band of suitable water, and that in turn was related to wind conditions. No bluefish larvae were collected in the Middle Atlantic Bight in January, April, May, and June 1966, but they were abundant and widespread in August when their distribution extended from east- ern Long Island, N.Y., to Virginia and more or less over the breadth of the continental shelf (Figure 3). They were most abundant off New Jersey and Delaware. Most of these larvae were small (mean, 4.0 mm SL) indicating that spawning had occurred not long before this cruise. The relative number of fish <4 mm SL was gi-eatest at the northern end of the survey area and diminished progressively southward to Delaware Bay ( Figure 4 ). This effect could have resulted from growth of the larvae dur- ing our sampling from north to south in this area over a 3-day period. It also might have resulted if bluefish spawning had started in the south and progressed northward. Either or both of these pro- cesses may have been involved. There was an 11-day gap in sampling between Delaware Bay (Transect F) and Maryland (Transect G). This might account for our finding so few, but larger larvae south of Delaware Bay. Bluefish spawning in middle Atlantic waters was almost finished by the end of summer, judging from the paucity of specimens taken during Sep- tember and October (Figure 5). In September, when we sampled only north of middle New Jer- sey, we caught two larvae; and in October, when the sampling area extended over the whole Middle Atlantic Bight, we again caught two. We have no information on the southerly extent of bluefish larvae during September, since there was no sam- pling south of New Jersey then. Four bluefish larvae were taken during winter cruises, one at each of four stations near the edge of the continental shelf. One was taken off North Carolina ( Transect N) and the other three between St. Augustine, Fla., and Palm Beach (Transects Y, KK, and LL). Figure 2.— Distribution of surface temperatures and larval bluefish in May. Transects A-P sampled May 1966; AA-PP sam- pled May 1967. 217 FISHERY BULLETIN: VOL, 77. NO, 1 Table 2. — Bluefish catches in paired neuston nets during eight weekly cruises off Cape Hatteras, N.C., April, May 1972. f 1 Tow 1 Apr, 2 18 Apr, 27 Apr, 4 1 Vlay 2 11 1 May 2 16 1 May 2 23 1 May 2 31 1 May Item 1 2 1 2 2 GuH Stream Surface temperature ('C) Bluetisti catcti rvlean length (mm SL) 22 ND 23,3 7 109 ND 22 5 12 89 224 218 100 23,5 8 11 6 ND 240 4 98 ND 25 1 ND ND ND 255 ND 200 m stioreward ot Gull Stream Surface temperature ( C) Bluelish eaten lytean length (mm SL) 160 4 48 ND 195 41 111 20 6 14 10 13,2 93 55 22 1 771 99 200 3 123 186 2 91 203 4 106 ND 226 6 120 ND ND ND 20 5 35 59 195 217 163 Intermediate (shelf) water; Surface temperature (°C) Bluefish catch Mean length (mm SL) 12 5 NO 10,6 117 ND ND 154 170 1 21 4 180 17 12,9 16 1 194 2 187 ND 15 1 ND 173 163 Nearshore: Surface temperature ( C) Bluefish catch Mean length (mm SL) 130 ND 108 ND ND ND ND ND 160 5 107 ND 195 2 188 20,0 ND ND 190 ND Temperature-Salinity Regimes During the survey, bluefish larvae occurred in two distinct temperature-salinity regimes. One regime was characterized by surface temperatures of 18°-26=C and salinities of .30-32%« (Figure 6i. These conditions prevailed from late spring through the summer above the thermocline in coastal waters of the Middle Atlantic Bight. Blue- fish spawning evidently did not begin there until late July or early August, judging from the small number of large larvae taken in August. Thus, spawning of bluefish in the Middle Atlantic Bight seemed to be influenced partly by features of envi- ronment other than temperature and salinity. The other regime was associated with the inner edge of the Gulf Stream and was characterized by surface temperatures of 20°-26°C and salinities of 35-38%(i. As mentioned above, few bluefish larvae occurred in this water during the fall and winter, considerable numbers during the spring, and none during the summer. Sea.S(>nal Surface Temperature Relations Regardless of season or area, nearly all larvae were taken in waters between 17° and 26°C. Lar- vae appeared on the shelf throughout the South Atlantic Bight in spring where the surface water temperatures ranged from 19° to 24.5°C. North of Cape Hatteras where we took no larvae in spring, shelf water was <15°C, but near the edge of the Gulf Stream where we did take larvae, tempera- tures were >15°C. At the stations where bluefish larvae were taken during August, surface tem- peratures ranged from 18.8° to 25.7°C. Surface water covering most of the Middle Atlantic Bight south of eastern Long Island was within this temperature range (Figure 3). However, south of Cape Hatteras no bluefish larvae were taken in July when temperatures were mostly >26°C. Sur- face water temperature had decreased between our September and October cruises. The 20°C sur- face isotherm was off Long Island in September, but had moved south to Virginia by October. The bluefish larvae were taken in 20.3°C water in Sep- tember and 16.4°C water in October. The few bluefish larvae taken near the edge of the conti- nental shelf off Florida in October were in water >25°C. In winter, all occurrences were in water >20°C, which was limited to the outer portion of the continental shelf from North Carolina to Florida at that time. Diel Cycles of Vertical Distribution The number of larvae caught in shallow tows (0-15 m) when compared with deep tows ( 18-33 m) during day and night provided limited informa- tion about diel cycles of vertical distribution. The catch rate was highly dependent on net depth. At the 46 stations where both nets were towed and either caught bluefish larvae, more occurred in the shallow net at 37 stations indicating that the lar- vae were more abundant in the shallow layer i sign test, P<0.001). Nearly all of the catch of the deeper net may have occurred as it passed through the surface layer during setting and retrieving. Figure 3. — Distribution of surface temperatures (left) and lar- val bluefish (right) in July-August. Transects A-P sampled Au- gust 1966; AA-PP sampled July-August 1967. 218 KENDALL and WALFORD SOURCES AND DISTRIBUTION OF BLUEFISH BLUEflSH LABVAE CftUtSE D -66 - rO AUG. 5 - 26, 1966 LAUVAE / STATION • NONE 1 -5 « - » iiilili"-"" ^■1 >200 219 FISHERY BULLETIN VOL 77. NO 1 FRa'KE 4.— Percent of bluefish larvae <4 mm SL captured on transects B-H (Figure 2l in the Middle Atlantic Bight in August 1966. Indeed, later studies (Kendall and Naplin^i have shown that bluefish larvae occur primarily within 6 m of the surface. The distribution of catches was similar during day and night (Table 3). Larval Lengths The length distribution of larvae taken in the shallow tows was not significantly different from that taken in deeper tows (x^P>0.05) (Table 4). This result is to be expected if, as indicated above, the catches in the deeper tows can be accounted for by contamination in the surface layer. Fish taken during the day, however, were generally smaller (2.5-4.5 mm) than those taken at night (5.5 mm and larger) (x''^ f <0.001). This effect could result from net avoidance by larger larvae during day- time. The cruises were too infrequent to estimate larval growth. Juveniles During the survey cruises we tried to collect pelagic juvenile fishes and during later cruises tried to clarify results from the surveys by sam- pling in areas and during seasons in which juveniles had occurred earlier. We took bluefish juveniles in several kinds of midwater and surface nets. It is difficult to compare the catches of these several nets or the catches made in different years; nevertheless, this limited information about ^Kendall, A. W.. Jr., and N. A, Naplin. Diel-vertical distribu- tion of bluefish iPomatomus sattatrix) larvae and that of as- sociated fish eggs and larvae. Manuscr. in prep. Northeast Fisheries Center Sandy Hook Laboratory, National Marine Fisheries Service. NOAA, Highlands, NJ 07732. Figure 5. — Distribution of surface temperatures and larval bluefish in September-October. •lUEFISH LAHVAE A -D: CftUISE D -66 - II A. '?: SEPT. 13 - le, \9U ^^C r. CKUISE D - 66 - 1 2 \^/ SEPT . a - OCT . 20, 1966 y^ -ft. CRUISE D-67-16 ./V _CAPt COO 9 y-^ ^. CAPE MAITfRAs/ ff ■" <===-^ '7 220 KENDALL and WALfORD SOURCES AND DISTRIBUTION OF BLUEFI! ,1 ' 18- 23 36 81 5 1147 256 7 1 18 1 1 3 - 1 22 11 19 2 48; 41 1 3 223; 18 ^193 1 3 14 NUMBER OF TOWS 1 ^ 33 3! SALINITY %■> 1- 1-n S-9 10-19 >19 FIOURE 6. — Clustering of catches of larval bluefish by temper- ature-salinity combination during RV Dolphin surveys, 1965- 68. Numbers of bluefish larvae superimposed on temperature- salinity combinations where they were caught. Table 3.— RW Dolphin 1965-68 ichthyoplankton survey. A com- parison of bluefish larval catches during day and night. Number of tows Larvae/tow Day Nighl \' t 12 6 309 2-10 6 7 0.303 1 1-1 00 7 7 080 100 3 2 078 Tolals 28 24 770 (3df.P 80) offshore seasonal geographic distribution of bluefish juveniles indicates a complex pattern of movements from offshore spawning areas to coastal and estuarine nursery areas. In summary we found bluefish juveniles, pre- sumably from the spring spawning, at the surface near the slope front from south of Cape Hatteras to off the Middle Atlantic Bight in April to June (Figure 1). We hypothesize that they move north- ward along the slope front, then cross the shelf, enter estuaries of the Middle Atlantic Bight and after spending the summer in the estuaries, re- turn to the sea and move southward along the coast and out of the Middle Atlantic Bight. Some juveniles from the summer spawning in the Mid- dle Atlantic Bight remain in coastal waters while some enter estuaries briefly. They too leave the Middle Atlantic Bight in early fall. The following is our evidence for these conclusions. In May 1967, juvenile bluefish were scattered over the continental shelf in the South Atlantic Bight and north to Cape Hatteras (Figure 7). The largest specimens were from stations near shore. In April and May 1971, we sampled the offshore area intensively around Cape Hatteras to find any trace of young bluefish which could be attributed to larvae and juveniles such as had appeared pre- viously to the south. During this cruise neuston tows took bluefish juveniles near the edge of the continental shelf ( 100-fm (183-m) isobath) (Figure 8a). All of the specimens taken were in water >15°C, which occurred all across the shelf south of Cape Hatteras, but only near the edge of the shelf north of there. In the June 1966 survey, when 59 stations were sampled, bluefish appeared at each of two widely Table 4.— RV Dolphin ichthyoplankton surveys 1966-68. Length distributions of larval bluefish collected in Gulf V samples. Soutti Atlantic Bight IVIiddle Atlantic Bight Shallow tows Deep tows Day Night midpoint (mm SL) D-66-1 Winter D-66-2 D-68-1 Spring Fall Summer All D-66-5 0-67-4 D-67-16 D-66-10 D-66-1 1 D-66-1 2 data 2.5 97 231 301 27 266 62 328 3.5 4 205 8 610 2 739 89 689 139 828 4.5 128 6 515 1 602 49 371 280 651 5.5 1 4 15 1 136 145 12 72 85 157 6.5 1 2 2 21 1 22 5 1 1 16 27 7.5 5 1 1 14 2 7 9 16 85 1 ; 8 5 13 2 10 5 15 95 2 1 5 7 1 2 6 8 10 5 10 10 to 10 11 5 1 1 2 1 1 2 125 1 1 1 13,5 1 23.5 1 1 Total 1 1 2 25 448 17 1.547 2 2 1,858 187 1,429 616 2.045 688 363 4 31 400 3 98 3 88 3 73 4 51 3 97 Variance 3 55 1 61 96 1 31 1 58 1 26 84 2 78 1 55 221 FISHERY BULLETIN VOL 77. NO I separated nearshore stations ( Figure 7 ). The regu- lar presence of bluefish juveniles in offshore wa- ters of the Middle Atlantic Bight in June was observed in three subsequent years. They occurred during 1969 only near shore; during 1970 only near the edge of the continental shelf; and during 1971 they were scattered over the shelf and slope (Figure 8b, c, d). The origin of these juveniles was puzzling, because there was no evidence of bluefish larvae in the Middle Atlantic Bight until midsummer. We had taken larvae and juveniles in April and May from Cape Hatteras south to Florida mainly offshore near the slope front. Ap- parently these fish become distributed along the slope front off the Middle Atlantic Bight in May and June and then cross the continental shelf in June as surface waters become suitably warm. Surface temperatures on the shelf are generally 15° to 20°C at this time, and most of the juveniles were taken in water >18°C. The juveniles we caught in August (Figure 7) were presumably products of recent spawning in nearby waters, for only slightly smaller larvae appeared in the plankton tows in the same area. One specimen 128 mm SL taken just outside Chesapeake Bay had probably been spawned in the spring off the South Atlantic Bight. We collected a few juveniles of widely differing sizes during two surveys in fall 1966. In a cruise conducted in 1970, we confirmed the regular pres- ence of juvenile bluefish in the Middle Atlantic Bight in fall. We then collected juveniles between Delaware and Chesapeake F^ays within 13 km of the shore ( Figure 8e); and several specimens about 200 mm SL in the same area. The juveniles from these cruises can be attributed to the summer spawning of bluefish in continental shelf waters of the Middle Atlantic Bight; and the fish about 200 mm SL to the southern spring spawning. The lat- ter fish had presumably spent the summer in mid- dle Atlantic estuaries ( Wilk") and had returned to the ocean. A 124-mm SL specimen taken in November may have originated from either spawning. No bluefish juveniles were taken in fall in the .South Atlantic Bight and neither larvae nor *Wilk,S.J. 1977. Biological and fisheries data on bluefi.sh, Pomatomus saltatrix (Linnaeus). Sandy Hook Lab. Tech. Ser. Rep. 11, 56 p. FIOIRE 7. — Months of capture lindicated by numerals) of juvenile bluefish at stations sampled by surface meter net and nndwater trawl during RV Dolphin surveys, 1965-68. 222 KENDALL and WALFORD SOURCES AND DISTRIBUTION OF BLUEFISH ■'•• ^^ J .v.>^=t^ >' ^^ . ^ i -**f /^\y,^r ^y *• tf\p^^^p'^'^ V ^-^■^-^ '^ J'. K ^"""^ ■..._*°^ 5S^'. / ir ^ — """^ / ss* ./ • 1 " \- 3«",- nr- CRUISE D-69-13 JUN 10-17, ® V V n' T Y cnuise 0-70-14 JUN 15-16. 1970 (M '^y CAM I y/^' FIGURE 8.— Distribution of juvenile bluefish and surface temperatures during six cruises over portions of the Middle Atlantic Bight. Sam- pling stations indicated by dots. F*resence of juvenile bluefish in sur- face meter net or Haednch net indi- cated by circles, m midwater trawls by triangles, and under nightlight by a star. CRUISE D 70-26 OCT 29-NOV I, 1970 © © 223 FISHERY BULLETIN VOL. juveniles were taken in the Middle Atlantic Bight from late fall to June. In the winter survey, a few juveniles were taken off Florida (Figure 7). but during a follow-up cruise, none were caught (Figure 8f). DISCUSSION The patterns of distribution of young stages of bluefish off the east coast can be summarized based on our collections and those of others (Table 5). From our collections of small larvae, bluefish appear to spawn in two quite different areas — in water just shoreward of the Gulf Stream (Florida Current) from Florida to Cape Hatteras, i.e., the South Atlantic Bight, and in shelf water from Cape Hatteras to Cape Cod, i.e., the Middle Atlan- tic Bight. In the South Atlantic Bight, spawning occurs primarily during spring and apparently also to a lesser extent in fall and winter. Most of the larvae we caught were well offshorejust shoreward of the Gulf Stream in water which was 20°-26°C and had a salinity of 35-38%o. Larvae from the spring spawning in the south- ern area are evidently carried northward past Cape Hatteras in April and May and become spread out along the continental slope off the Mid- dle Atlantic Bight. As shelf waters become suit- ably warm, generally in mid-June, the young bluefish appear to cross the shelf and enter es- tuaries, where they spend the summer. There they grow from 25-50 mm SL to 175-200 mm SL (Wilk see footnote 6) and in early fall migrate south along the coast. Larvae from the fall and winter spawning in southern waters may find their way inshore south of Cape Hatteras as indicated by a few juveniles which we found in Florida in winter. The spawning in the Middle Atlantic Bight in continental shelf waters occurs in summer. The water in which larvae were found here was 3°C cooler and 5%o less saline than that in the south- T.i^BLE 5. — Collections of bluefish eggs, larvae, and juveniles, east coast of United States. Sampling period Sampling area Occurrences of bluefish Numbers Lengths (mm) Reference Years Months Eggs Marak and Colton (1961): 1951-56 Feb -June Ocean ofl New England Late May-early June 1953 tew Marak. . . Foster (1962), south of Martha's Vineyard Marak, , Miiler (1962) Norcross el al (1974) 1959-60 all except Oct Ocean oft Chesapeake Bay June, July, August 1960 and 1961 1961-62 all Ocean oft Chesapeake Bay July 1962, nearshore to slope waters many 1962 seasonally Ocean off Chesapeake Bay 1963 July Aug Ocean oft Chesapeake Bay Larvae: Selle (quoted by 1929 Apr -July Ocean Irom Cape Cod- 40'N-Chesapeake Bay, waters near many 3-21 Perlmutter 1939) Chesapeake Bay 21 C, mostly outer half of shelf Herman (1963) 195758 all Narragansen Bay July, 20 7 C 1 3 Lund' 1965 May, July-Sept Ocean oft eastern Long Island July-Sept (most in Aug ) 73 5-30 1966 June-SepI Ocean oft eastern Long Island 981 5-20 deSylva et al (1962) 1956-58 all Indian River Inlet Del Aug -Sept 2 4-28 Pearson ( 1 94 1 ) 1929-30 all Lovner Chesapeake Bay 24 July, at mouth of bay 4 4-7 Norcross el al (1974) 1959-60 all except Oct Ocean oft Chesapeake Bay May-Aug 34 3-7 1961-62 all Ocean oft Chesapeake Bay July-Sept, 441 3-11 1962 seasonally Ocean oft Chesapeake Bay July 34 5-14 1963 July, Aug Ocean oft Chesapeake Bay July-Aug, 93 4-22 Juveniles (■ 100 mm) Pearcy and Richards (1962) 1959-60 all Mystic River, Conn Seined, July-Aug lower estuary 2 75-94 Perlmutter (1939) 1938 all Waters around Long Island Throughout summer— small fish trawl Throughout summer — seined small 6 78-96 Lund' 1968 July-Sept Shmnecock Bay, N Y 200 40-100 (40 mm) fish in July and Aug deSylva el al (1962) 1958 every other Delaware River Del Seined, June-Sept, lower " estuary 130 30-100 Pacheco and Grant (1965) 1957-58 all White Creek, Del Seined May- June, Sept 45 39-104 Richards and Castagna (1970) 1965-66 all Eastern shore of Virginia Trawled, at mlets. July, Sept 5 31-85 Tagae and Dudley (1961) 1957-60 all Shoal waters near Beaufort, N C Seined, May-July, Ocl-Nov, 37 40-100 Turner and Johnson (1973) 1970 all Newport River. N C Surface, trawled, upper river May, July, Oct few 45-72 'Lund, W A . Jr Early life history of the bluelish, I'l Res Lah . Noank, Conn . 23 p sntttjtrix ( Linnaeus). (tfT the coast of" New Yurk and southern New Knjiiand, Contrib 64 Mar 224 KENDALL and WALFORD SOURCES AND DISTRIBUTION OF BLUEFISH ern area (18'-26'C and 30-32°/„o). Bluefish larvae have been reported by other authors in this area from May through September, but mostly in July and August (Table 5). Larvae have also been re- ported in the more saline areas of several estuaries of the Middle Atlantic Bight (Table 5). Although some juveniles from the Middle Atlantic Bight spawning inhabit estuaries in late summer, more seem to remain along the shore. Nevertheless, all appear to move southward and out of the bight in midfall. Their distribution in late fall and winter is still unknown. From the scarcity of juveniles (i.e., fish 50-150 mm SL) in our samples at sea, and the abundance of these fish in estuarine collections, it appears that bluefish depend chiefly on estuaries for habitat during this stage. Their dependence is de- termined by the time and place of their spawning. Those from the spring spawning spend most of their first summer in estuaries, while those from the summer spawning spend at most about a month there. Both changes in temperature and seasonal photoperiod influenced the activity and distribution of adult bluefish at least under laboratory conditions (011a and Studholme 1971, 1972 1. Thermal edges may act as barriers affecting the distribution of juvenile bluefish, as shown in recent laboratory work (OUa'). These factors, and possibly others, probably trigger movements of juveniles from the open ocean to estuaries and back to the open ocean. In order to assess the relative proportions of the two major spawning areas to the total recruitment of bluefish on the Atlantic coast in any given year, it would be necessary to sample repeatedly during the spring south of Cape Hatteras and during the summer in the Middle Atlantic Bight. Our" present limited understanding of early life history contributes to several other facets of bluefish biology. Population differences of bluefish on the U.S. Atlantic coast have been studied using meristic characters (Lund 1961), migratory pat- terns, morphometries, and scale morphology ( Wilk see footnote 6). All of these studies indicate that more than one population exists. Scale studies defined two groups of bluefish by the size of fish when the first annual ring forms in May. One group, which reaches about 260 mm by the end of 'B. L- 011a. Northeast Fisheries Center Sandy Hook Laborato- ry. National Marine Fisheries Service. NOAA. Highlands. N-J 07732, pers. commun. August 1978. its first winter, evidently represents fish spawned in spring south of Cape Hatteras. The other group, which reaches only about 1 20 mm by the end of its first winter, represents fish spawned in the sum- mer in the Middle Atlantic Bight. Body propor- tions of these two groups of fishes are statistically different (Wilk see footnote 6). Precise information on adult bluefish migration is not available, but general patterns are known ( Wilk see footnote 6). Some mature bluefish spawn near the inner edge of the Gulf Stream as they migrate northward from their wintering grounds off Florida. To a lesser extent some bluefish also spawn in the same area in fall and winter, pre- sumably on their return migration. Adult bluefish migrate to coastal waters off the Middle Atlantic Bight in spring and feed there until they migrate south coincident with fall cooling. During their stay in the Middle Atlantic Bight, bluefish spawn on the shelf, and to some extent in mouths of the larger estuaries (Norcross et al. 1974). Although spawning can take place as soon as the adults arrive in the area in May, most seems to occur in July and August, while some continues into Sep- tember. From the apparent annual variations in timing and amount of this spawning, it is depen- dent on a combination of several features of the environment including temperature, salinity, photoperiod, and food for the adults. If each mature fish spawns in both areas and in all seasons, this would indicate that there is a single stock of bluefish on the east coast of the United States. If each fish spawns in only one area, separate populations must exist. Our early life history information is consistent with other in- formation that indicates that there are separate populations. Southern and northern spawnings take place under quite different hydrographic conditions and in quite different current regimens to assist the young fish in movements to nursery grounds. In time these conditions could allow genetically distinct populations to become estab- lished. Tagging and fecundity studies would show to what extent this has happened. Since year-class strength of fishes is determined mainly during their young stages, it is important to understand the factors influencing survival of these stages. In bluefish, the eggs and larvae occur at the surface of the ocean and the juveniles occur in estuaries, areas affected by annual varia- tions in weather-related phenomena and, to an increasing extent, affected by man's activities. It is thus important to monitor these influences and 225 FISHERY BULLETIN: VOL 77. NO 1 develop models to relate them to year-class strength of the various spawnings of bluefish. ACKNOWLEDGMENTS John R. Clark, now of the Conservation Founda- tion, Washington, D.C., while at Sandy Hook Laboratory, supervised the initial work on bluefish larvae from the RV Dolphin collections. Several people helped in use of unpublished data in preparation of this paper: Stuart Wilk, NMFS, Sandy Hook, N.J.; David Deuel, NMFS, Nar- ragansett, R.L; and Sally L. Richardson, Oregon State University. Omie Tillet, Nags Head, N.C., helped make the sampling near Cape Hatteras in spring 1972 pleasurable as well as successful. LITERATURE CITED AGASSIZ, A.. .\SD C. O. WHITM.1N. 1885. Studies from the Newport Marine Laboratory. XVI. The development of osseus fishes. I. The pelagic stages of young fishes. Mem. Mus. Comp. Zoo). Harvard Coll. 14(11, 56 p. BARTLETT, M. R., and R. L. Haedrich. 1968. Neuston nets and south Atlantic larval blue marlin iMakaira nigricans). Copeia 1968:469-474. Bigelow, H. B., and W. C. Schroeder. 1953. FishesoftheGulf of Maine. U.S. Fish Wildl. Serv., Fish. Bull- 53, 577 p. BRIGGS. J. C. 1960. Fishes of worldwide (circumtropicat) distribu- tion. Copeia 1960:171-180. Clark, J. , W.G.SMITH, A. W.KENDALL, Jr.. and M. P. FAH AY. 1969. Studies of estuarine dependence of Atlantic coastal fishes. Data Report I: Northern section. Cape Cod to Cape Lookout. R.V. Dolphin cruises 1965-66: Zooplankton vol- umes, midwater trawl collections, temperatures and salinities. U.S. Bur. Sport Fish. Wildl., Tech. Pap. 28. 132 p. 1970. Studies of estuarine dependence of Atlantic coastal fishes. Data Rep. II: Southern section. New River Inlet. N.C.. to Palm Beach. Fla. RV . Dolphin cruises 1967-68: Zooplankton volumes, surface-meter net collections, temperatures, and salinities. U.S. Bur. Sport Fish. Wildl , Tech. Pap 59, 97 p. Colton, J. B., Jr., AND K. A. Honey. 1963. The eggs and larval stages of the butterfish Poronotus triacanthus. Copeia 1963:447-450. DE SYLVA, D. p., F. a. KALBER. Jr., and C. N. SHU.STER, JR. 1962. Fishes and ecological conditions in the shore zone of the Delaware River estuary, with notes on other species collected in deeper waters. Univ. Del. Mar. Lab . Inf Ser, Publ. 5, 164 p. DEUEL, D. G., J. R. CLARK, AND A. J. MANSUETI. 1966. Description of embryonic and early larval stages of bluefish, Pomatomus saltatnx. Trans. Am. Fish. Soc. 95:264-271. Fowler, H. W 1944. Results of the Fifth George Vanderbilt Expedition (1941), (Bahamas, Caribbean Sea, Panama, Galapagos Archipelago and Mexican Pacific Islands). Fishes. Acad. Nat. Sci., Phila., Monogr. 6:57-529. Herman, S. S. 1963. Planktonic fish eggs and larvae of Narragansett Bay. Limnol Oceanogr. 8:103-109. Irvine, F R 1947 The fishes and fisheries of the Gold Coast. Crown Agents for the Colonies. Lond., 352 p. LUND, W. A., JR. 1961. A racial investigation of the bluefish, Poniatomus saltatnx (Linnaeus) of the Atlanticcoast of North Ameri- ca. [Span. Abstr.) Bol. Inst. Oceanogr., Umv. Oriente Cumana 1:73-129. LUND, W. A., JR., AND G. C. M.->lLTEZOS. 1970. Movements and migrations of the bluefish. Poniatomus saltatnx, tagged in waters of New York and southern New England. Trans. Am. Fish. Soc. 99:719- 725. MARAK, R. R., and J. R. COLTON. jR. 1961. Distribution offish eggs and larvae, temperature, and salinity in the Georges Bank-Gulf of Maine area, 1953. U.S. Fish Wildl. Serv, Spec. Sci. Rep. Fish. 398, 61 P MaRAK. R. R.. J. B. COLToN. Jr., and D. B. Fo.ster. 1962. Distribution of fish eggs and larvae, temperature, and salinity in the Georges Bank-Gulf of Maine area, 1955. U.S. Fish Wildl. Serv, Spec. Sci. Rep. Fish. 41 1, 66 P M ARAK , R. R. J. B. Colton. Jr., D. B. Fo.ster, and D. Miller. 1962. Distribution of fish eggs and larvae, temperature, and salinity in the Georges Bank-Gulf of Maine area, 1956. U.S.FishWildl.Serv.Spec.Sci Rep Fish.412,95 P NORCROSS, J. J., S. L. RlCH.ARDSON, W. H. MASSMANN, AND E. B. JOSEPH. 1974. Development of young bluefish {Poniatomus saltat- nx) and distribution of eggs and young in Virginian coast- al waters. Trans. Am. Fish. Soc. 103:477-497. Oben, L. C. 1957. About the drifting approach of fingerling bluefish. Pomatomus saltatnx L.. to the shores of the Black Sea in the region of the Karadag 1 1947-1954). Translated from the Russian language by M. J. Koushnaroff and R. J. Mansueti from worksof the Daradag Biol Stn., Acad. Sci. Ukr USSR 14:155-157. OLLA, B. L., AND A. L. STUDHOLME. 1971. The effect of temperature on the activity of bluefish, Pomatomus saltatnx L. Biol. Bull. (Woods Hole! 141:337-349. 1972- Daily and seasonal rhythms of activity in the bluefish iPoniatomus saltatnxh In H. E. Winn and B. L. Olla (editors!, The behavior of marine animals. Volume 2: Vertebrates, p. 303-326. Plenum Press, NY. PACHEGO, a. L., AND G. C. GRANT. 1965. Studies of the early life history of Atlantic menha- den in estuarine nurseries. Part I — Seasonal occurrence of juvenile menhaden and other small fishes in a tributary creek of Indian River. Delaware, 1957-58. U.S. Fish Wildl. Serv,, Spec, Sci. Rep. Fish. 504, 32 p. Padoa, E, 1956. Uova, larvae stadi giovanili di teleostai: familia Z: Pomatomidae. Fauna Flora Golfo di Napoli, Monogr. 38:570-572. 226 KENDALL and WALFORD SOURCES AND DISTRIBUTION OF BLUEFISH Pearcy. W, G,, and S. W. Richards. 1962. Distribution and ecology of fishes of the Mystic River estuary, Connecticut. Ecology 43:248-259. Pearson, J. C. 1941. The young of some marine fishes taken in lower Chesapeake Bay, Virginia, with special reference to the gray sea trout, Cynoscion regalts (Bloch). U.S. Fish Wildl, Serv,, Fish. Bull. 50:79-102. Perlmutter, a. 1939. Section I, An ecological survey of young fish and eggs identified from tow-net collections In A biological sur- vey of salt waters of Long Island, 1938, Part II, p. 11-71. N.Y. Conserv. Dep., Suppl, 28th Annu Rep., 1938, Salt- water Surv. 15. RK HAKIIS, E. C, AND M. CASTAIINA. 1970. Marine fishes of Virginia's Eastern Shore I inlet and marsh, seaside waters). Chesapeake Sci. 11:235-248. Salekhova, L. p. 1959. On the development of the bluefish iPomatomus Hal- tatnx) Linne, Tr. Sevastop. Biol, Stn. 11:182-188. SETTE. 0. E. 1943. Biology of the Atlantic mackerel {Scomber scorn- 6n^it of North America. Part 1: Early life history, includ- ing the growth, drift, and mortality of the egg and larval populations. U.S. Fish Wildl, Serv., Fish. Bull. 50:149- 237. SMITH, J. L, B, 1961. The sea fishes of southern Africa. 4th ed. Central News Agency. Ltd., South Africa, 580 p. SVERDRUP, H. U., M. W. Johnson, and R. H. Fle.ming, 1942. The oceans. Their physics, chemistry, and general biology. Prentice-Hall, Inc., Englewood Cliffs. N.J,, 1087 p. Taoatz, m. e., and d. l. Dudley. 1961. Seasonal occurrence of marine fishes in four shore habitats near Beaufort, N.C., 1957-60, U.S. Fish Wildl. Serv,, Spec. Sci. Rep Fish, 390, 19 p. Turner, W, R., and G. N, Johnson, 1973, Distribution and relative abundance of fishes in Newport River, North Carolina U,S Dep, Commer,, NOAA Tech, Rep, NMFS SSRF 666, 23 p, Wrii;ht, W, R,, and C, E, Parker, 1976, A volumetric temperature/salinity census for the Middle Atlantic Bight, Limnol, Oceanogr, 21:563-571, 227 CONTRIBUTION OF 1960-63 BROOD HATCHERY-REARED SOCKEYE SALMON, ONCORHYNCHUS NERKA, TO THE COLUMBIA RIVER COMMERCIAL FISHERY Roy J. Wahle, Reino O. Koski, and Robert Z. Smith' ABSTRACT A 4-yr marking program was conducted at Leavenworth National Fish Hatchery, Leavenworth, Wash., to determine the contribution of hatchery sockeye salmon, Oncorhynchus nerka, to the Colum- bia River commercial fisheries and the economic feasibility of hatchery rearing of sockeye salmon. The study involved 1960 through 1963 brood-year fish. During the 4-vr period, 1961-64, a total of 11.5 million fish were released, of which 3.4 million were marked by the removal of the adipose fin and part ofoneof the maxillary bones — the right maxillary for 1960 and 1962 broods and the left maxillary for 196 1 and 1963 broods. Trapping at the lake outlet in the spring for the first 2 yr indicated that less than 50^f of the stocked fingerlings migrated. In 1964-67. recovery of marks from thecommercial fishery on the Columbia below and the Indian fishery above Bonneville Dam showed that an average of 13.6% of the sockeye salmon catch was composed offish raised at Leavenworth Hatchery. Adjusting for effects of marking, this represents an average fishery value per brood of $4,274.75. The average potential benefit/cost ratio for the 4 yr of the program was 0.04 to 1. Because preliminary data indicated such a low benefit/cost ratio, sockeye salmon rearing at Leavenworth was radically decreased in 1966 and terminated in 1969. In the 1930's Grand Coulee Dam was constructed on the upper Columbia River, thus barring anad- romous fish runs from 1,835 km of spawning and rearing area. The extreme height of the dam ( 106 m) precluded building passage facilities for both upstream and downstream migrants. To preserve the runs formerly utilizing the upper basin, a relo- cation of runs of affected species became neces- sary. Basic data on existing fish populations were ob- tained from 1933 through the time of dam comple- tion in 1941 (Fish and Hanavan 1948). The only relocation areas suitable for spawning and rearing were Columbia River tributaries below Grand Coulee Dam and above Rock Island Dam. The area was less than one-half the extent of that formerly available and on streams which, because of in- dustrial diversion, were for the most part inacces- sible to migrating fish. Because of general deple- tion of all the upriver salmonid runs, correction of fish passage problems was already underway in many areas. With the impetus of the relocation program, further rehabilitation was ac- complished. 'Environmental and Technical Services Division. National Marine Fisheries Service, NOAA, 811 N.E. Oregon, Portland, OR 97208. Manuscript accepted September 1978. FISHERY BULLETIN VOL. 77, NO 1, 1979. The sockeye salmon, Oncorhynchus nerka, was seriously affected by the habitat changes as its development required a lake-stream environment which has been almost completely eliminated. Annual commercial catches of Columbia River sockeye salmon ranged from '/2 to 2 million kg prior to 1900 (Gangmark and Fulton 1952). From then through the early 1920's annual catches var- ied from about 'a million to over 1 million kg. Following one more good year in 1926, the V2 mil- lion kg figure was never again reached (Figure 1). Estimates of escapement beyond the fishery were not possible until enumeration of migrating adults began in 1933 at Rock Island Dam, 755 km above the mouth of the Columbia River. An aver- age of about 19,000 adults was counted annually until 1 94 1 , when only 949 adults passed upstream. The low escapement was caused by a large com- mercial catch, low flows, and retention of water behind Grand Coulee Dam (Fish and Hanavan 1948). The relocation of runs began in 1939 for sockeye salmon as well as chinook salmon, O. tshawytscha: coho salmon, O. kisutch; and steelhead trout, Salmo gairdneri . Adult sockeye salmon were trapped at Rock Island Dam and were transported by tank trucks to the Wenatchee and Okanogan 229 FISHERY BULLETIN VOL 77, NO. 1 0,0 1890 1900 1910 1920 YEAR 19 30 1940 I960 FIGURE 1,— Commercial catch of sockeye salmon in the Columbia River, 1889-1967. (Data for 1889-1936 from Craig and Hacker (1940), for 1937 from Ward et al. ( 19631 and for 1938-67 from Fish Commission of Oregon and Washington Department of Fisheries (1968),] Lakes where they were alIowe(i to spawn natu- rally (Figure 2), Supplementary to adult relocation, an artificial propagation program was planned. A hatchery was constructed on Icicle Creek, a tributary of the Wenatchee River near Leavenworth, Wash, (Fig- ure 3). Smaller substations were built on the Entiat and Methow Rivers. The sockeye salmon production progi'am was to be concentrated at Leavenworth National Fish Hatchery, Fish produced at Leavenworth were stocked into Wenatchee and Osoyoos Lakes. Success of the sockeye salmon relocation program was indicated in 1947 when the largest run recorded since 1926 appeared. This raised the question of whether the remaining available spawning habitat was over- populated, prompting annual inventories that continued for many years (Gangmark and Fulton 1952). How much of the apparent improvement in sockeye salmon runs was attributable to hatchery production was unknown. Importance of the Wenatchee system for total sockeye salmon pro- duction was obvious. Data indicated that an aver- age of 33''f of upper Columbia River sockeye salm- on homed to the Wenatchee River in the 7 yr just prior to this study (French and Wahle 1965). Wenatchee System Sockeye Salmon Stock For over 25 yr Leavenworth Hatchery produced sockeye salmon which were stocked and reared in Wenatchee River tributaries. During this time, five major dams were built on the main Columbia River downstream. These structures, combined with growth and expansion in population and in- dustry, added greatly to existing problems which confronted both downstream migrants and return- ing adults. The Wenatchee River system was historically an excellent salmon producing system. It was comparable, for sockeye salmon production, to the Arrow Lakes, Yakima Basin, and Okanogan Lake areas, formerly the primary producers of this species in the basin (Figure 2). In the early 1900's the runs in the Wenatchee became severely de- pleted because of construction of impassable mill and power dams and unscreened irrigation proj- ects. These conditions prevailed until the early 1930's, at which time about 85% of the Columbia 230 WAHLE ET AL,. 1960-63 BROOD HATCHERY-REARED SOCKEYE SALMON Scale in kilometers Figure 2. — Portion of Columbia River Basin showing areas of past and present importance to sockeye salmon as described in t*xt. River run was being produced in the Arrow Lakes area (Fulton 1970). The Grand Coulee Fish-Maintenance Project (Fish and Hanavan 1948) began in 1933. Under this project, obstructions were removed, dams were provided with passage facilities, and irriga- tion diversions were screened. These measures were necessary to establish suitable habitat for the relocated runs in tributaries between Grand Coulee and Rock Island Dams. To reintroduce sockeye salmon to the spawning areas above Lake Wenatchee and provide eggs for 231 FISHERY BULLETIN VOL 77. NO 1 N "J' LAKE WENATCHEE N 6 T N OREGON ONNEVILLE /DAM \ VTHE DALLES DAM VICINITY MAP MIGRANT' TRAP «l^ E« I LEAVENWORTH HATCHERY ROCKY REACH DAM 16 32 1 KILOMETERS ROCK ISLAND DAM Figure 3. — The Wenatchee River system and location of Leavenworth National Fish Hatchery. Leavenworth Hatchery, adult fish were trapped from 1939 through 1943 at Rock Island Dam on the main Columbia. Because the proposed hatch- eries would not be available to handle fish until 1940, adults of all displaced species were released for natural spawning in predetermined locations. Separate areas were selected for each species to prevent overcrowding and mixing. Most of the sockeye salmon transplanted undoubtedly origi- nated in the Arrow Lakes, but fish from the Okanogan and Wenatchee systems were certainly included (Fulton 1970). 232 WAHLE ET AL 1960-63 BROOD HATCHERY-REARED SOCKEYE SALMON Under the Grand Coulee Fish-Maintenance Project, sockeye salmon adults were trapped in July and August and hauled by tank truck to Lake Wenatchee, 113 km above Rock Island Dam, where a barrier was installed at the outlet. When spawning time approached, the fish ascended the White and Little Wenatchee Rivers where they spawned. When eggs were later needed for hatch- ery use, weirs were installed and adults trapped to supply the required ova. Surplus adults were al- lowed to pass upstream and spawn naturally. The offspring of these natural spawners homed back to the system to establish the new Wenatchee stock. Spawning occurred in September and October. The fry emerged from the gi-avel in spring and drifted back down to the lake to rear until the following year. Outmigration occurred in April and May, with a peak reached in early May prior to the heavy spring run-off period (French and Wahle 1959). Following 2, or occasionally 1 or3,yr at sea, the adults entered the Columbia River in late spring. The run passed Bonneville Dam in late June and early July, and several weeks later ascended the Wenatchee River to renew the cycle. The Hatchery Leavenworth National Fish Hatchery was com- pleted in 1940 as the primary station to provide hatchery-reared fish to supplement the newly es- tablished natural runs. Sockeye salmon were to be produced there and adults of other species were spawned to obtain stock to supply the satellite stations on the Entiatand Methow Rivers (Figure 2). The hatchery capacity was approximately 3.5 million eggs and 2.4 million fingerlings (Fish and Hanavan 1948). The source of eggs for the first 5 yr of operation was fish that had been hauled to Lake Wenatchee from Rock Island Dam as part of the relocation project. After this period the adult transportation was terminated and spawning operations con- tinued using fish returning to the lake naturally. After the eggs were taken and fertilized, usually in September, they were transferred to the hatch- ery for incubation. Hatching began in January and the fry began to feed about 6 wk later. Initial rearing took place inside the hatchery, and when water temperatures became suitable, they were placed in outside rearing ponds. In September or October, upon reaching an average weight of 9 to 10 g, the fingerlings were trucked to the lake. Survival from egg to stage at release ranged from 62 to 967f . After winteringover until the following April or May, the smolts migrated out of the lake. From general observations, it appeared that the hatchery operation was a success: proper rearing techniques were followed, hatchery migrants were observed leaving the lake, adults returned to the area in adequate numbers, and fish were available for commercial harvest. Data obtained through spawning surveys and downstream migrant counts at the dams indicated that the sockeye salmon population was being satisfactorily main- tained. However, it was not possible to determine whether the wild stock or the hatchery fish con- tributed most to the runs. Downstream migrant studies by Anas and Gauley 1 1956 1 pointed out the impossibility of identifying the separate stocks. There were indications that the costs of conduct- ing a sockeye salmon hatchery program were sig- nificantly higher than the values contributed to the fishery. Despite complexities of measurement of runs, some means of assessment seemed neces- sary. Thus, a study was designed to evaluate the economic feasibility of continuing artificial propa- gation of sockeye salmon at the hatchery. The study involved the marking of a proportion of the hatchery sockeye salmon production for a period of 4 yr, observations on the rearing and migration of the fingerlings, and estimation of the contribution of returning adults to the commercial fishery. An analysis of production costs and the monetary benefits to the fishermen was included. FIELD OPERATIONS Estimating Procedures The procedures used in making estimates of numbers offish are similar to those described in reports by Worlund et al. (1969) and Wahle et al. (1974). Estimates of the potential contributions and value of hatchery sockeye salmon required four steps: 1) estimation of marked and un- marked hatchery releases, 2) estimation of catch of marked adults, 3) estimation of total contribu- tion of hatchery fish to the catch, and 4) applica- tion of dollar values to the estimate of contribu- tion. Marking and Release Procedure The study began in July 1961, using 1960-brood fingerling sockeye salmon. Each year, approxi- 233 FISHERY BULLETIN VOL. 77, NO. 1 mately one-third of the total Leavenworth Hatch- ery stock was marked. In each year except the first, a circular net pocket with a metal sleeve and a tub sampler were used to obtain a sample offish for marking. Two types were employed: a 3-pocket sampler which gave an approximate 33.3'7( sample for marking, and a 10-pocket sam- pler (Worlundetal, 1969; Wahleetal. 1974) which provided a 10% sample for population estimate. In 1961, the one-third sample was obtained by mark- ing every third pond, and in the other 3 yr the fish to be marked were selected as described above. In 1961, hatchery personnel marked 1,008,310 1960-brood sockeye by removing the adipose fin (Ad) and part of the right maxillary bone ( RM). In 1962, the 1961-brood fish (600,036) were marked by removal of the adipose fin and part of the left maxillary bone (LM). The 1962-brood fish (1,146,485) were marked the same as the 1960- brood, and the 1963-brood (606, .578) repeated the 1961-brood mark. In 1961 the marked and unmarked fish were kept in separate ponds and mortality records kept for each group. The number of unmarked fish for release was estimated by using the number of eggs and the percentage of hatch, and subtracting the number marked plus pond mortality. As the fish were stocked, in order to avoid bias, the marked and unmarked fish were mixed in each truck load. In the three following years, by knowing the actual number offish marked for each brood year, and the postmarking mortality, the total popula- tion at release time was estimated. Using the 10- pocket sampler on a random group of fish from a pond, a 10% sample was obtained. Repeating this procedure on the 10% sample provided a 1% sam- ple, and a Peterson index of sample size was calcu- lated (Table 1). The fingerlings were transported by tank truck and released into Lake Wenatchee each fall. Table l. — Numbers of socke.ve released into Lake Wenatchee, Wash., during marking program. Brood Mark' No marked No. unmarked % marked Total released 1960 1961 1962 1963 Total Ad-RM Ad-LM Ad-RM Ad-LM 1 ,000,725 571.726 1.247.755 570.735 3.390.941 1.760.319 1.327.878 2.554,809 2,504,344 8.147,350 36,24 30 10 3281 18,56 29 39 2,761,044 1 ,899,604 3.802.564 3.075.079 11,538,291 'Ad - adipose fin; RM = rigiil maxillary bone, LM = left maxillary bone In the spring of 1962 and 1963, a trap was oper- ated at the lake outlet to monitor the outmigra- tion. Data obtained at the trap indicated that <50% of the marked fish migrated downstream. This amounted to 38.4% of the marked fish of the 1960-brood and 47. 9^/^ of the 1961-brood. Marked Fish Recovery Sampling for returning marked adults began in 1964 and continued through 1968. Earlier returns were not expected because prior studies at Lake Wenatchee indicated that few, if any, adults would return in their third year (Major and Craddock 1962). The search for marks was confined to the two commercial fishing areas in the lower Colum- bia River: zones 1-5, the gill net fishery below Bonneville Dam, and zone 6, the Indian set net and dip net fishery above the dam (Figure 3). Other fisheries were not sampled as Columbia River sockeye salmon rarely occur in the ocean commer- cial catch and are seldom taken by sport anglers (Koski 1964). We looked for marked fish during the commer- cial seasons. The zone 6 catch was monitored at Washington and Oregon Indian fishery buying stations. Commercial canneries in the lower river were sampled for the zones 1-5 gill net catch. Un- fortunately for the study, the commercial gill net season in zones 1-5 was closed in 1965 and 1966, and opened only for 5 days in 1964 (Fish Commis- sion of Oregon and Washington Department of Fisheries 1968). The zone 6 catch was also limited by this restriction, severely reducing the total catch (see Table 4). The catch in the 7 yr previous to the study averaged 90,900 fish. During the study period the average was only 22,500 ranging from 4,361 to 56,200 (Figure 4). Sampling Results Nearly one-half of the Columbia River commer- cial sockeye salmon catch was inspected for marks each year, except in 1966 when only a 4.2% sample was obtai ned because of the erratic nature of 1 and- ings. The extremely small sample undoubtedly biased the estimation of catch for the brood years involved. For most brood years, the majority offish were caught in their fourth year (Table 2). For all broods except the 1962 group an average of 94% was caught at age 42 (4 - total age, 2 - seaward migration age). This age-group represented only 4% of the total 1962-brood fish caught in 1966, evidence that the age 4^ fish were almost entirely missed by the fishery, although undoubtedly available. 234 WAHLE ET AL 1960-63 BROOD HATCHERY-REARED SOCKEYE SALMON 350 — m i i i I I i I ^ ^ SAMPLING YEARS THIS STUDY I i I i ii i w ?^ ^ Figure 4.— Columbia River sockeye salmon commercial catch in thousands, as part of the total run. 1957-68. [Data from Fish Commission of Oregon and Washington Department of Fisheries (1968).] 65 66 67 68 Table 2— Sampling rate and marks observed in Columbia River commercial fishery for sockeye 1960-63 broods. No of marks observed by brood year 1960 1961 1962 1963 265 Catch year Fishery zone' Total catch Number sampled Percent sampled 1964 1-5 4.950 3,307 6 15,820 7,195 Total 20.770 10,502 50 6 1965 1-5 70 24 6 5.773 3,024 Total 5.843 3,048 52 2 1966 1-5 157 27 6 Total 4.204 4.361 158 185 4.2 1967 1-5 21.218 7.993 6 35,002 13.885 Total 56.220 21.878 38 9 1968 1-5 20.300 9.689 6 5.000 2,632 Total 25,300 12.321 48 7 Total 287 16 310 Vone 1-5 (below Bonneville Dam), Zone 6 (above Bonneville Dam) 235 The number of fish in the catch, the number sampled and the number of marks recovered from zones 1-5 and zone 6, were combined. CALCULATIONS Because the marks used to distinguish the groups of hatchery fish have a negative effect on survival, two different steps were employed to cal- culate the hatchery fish contribution. The deter- mination of the level of contribution required an estimation of the number of hatchery fish in the catch for each year sampled. This was calculated from the estimated number of marked fish plus the estimated number of hatchery unmarked after a correction for differential mark mortality. Poten- tial catch is that which would be expected if mark- ing did not cause postrelease mortalities. Differential Mark Mortality (Survival Factor) We suspected that there would be adverse ef- fects on the survival of the fish because of the excised fin and maxillary bone. Foerster (1968) reported that marked sockeye salmon at Cultus Lake had an estimated return of only 38'/f of the unmarked return. To obtain a mark survival factor, a modification was made to the procedure for marking the 1961- brood fish. In addition to the group that received an Ad-LM, a second gi-oup received only a chemi- cal (tetracycline) mark, while a third had both marks. In sampling returning adults, a compari- son of the three groups showed that only 40^ of Ad-LM fish expected, returned (Weber and Wahle 1969). Because we believe that tetracycline had no effect on survival, we considered that the differ- ence between returns was caused by mortality due to marking by excision. Marks in Catch To calculate the number of marks in the catch for a certain year, the number of ri marks in the sample was divided by the sampling ratio: n marks (catch) n marks (sample) I) fish (sample)//! fish Icatch) This assumed a random sample of the catch. The mark survival factor was not considered in this equation. 236 FISHERY BULLETIN: VOL, 77. NO. 1 Hatcher)' Contribution to the Fishery To determine the percent of sockeye caught in a specific year that originated at Leavenworth Hatchery, the number of (n) unmarked hatchery fish in the catch was estimated by using the number of(n) marked fish in the catch and divid- ing by the sampling ratio and the marked unmarked ratio at release, corrected by the mark survival factor. The correction was necessary be- cause this ratio changes from the time of release to time of catch due to the effects of marking: n unmarked hatchery catch = ft marks icatch) n fish (sample) n marked release „ fish (catch. "" Tiinrmarked releas^ "" «""'^^' f^'^'"'- Summing the marked and unmarked hatchery fish for a catch year and dividing by the total catch gave the estimated percent produced by the Leavenworth Hatchery. For 1964-67, contribu- tions averaged 13.&/t of the total catch (Table 3). The 21.6'7f figure for 1966 may not be representa- tive as the sample size that year was small. T.^BLE 3. — Estimated numbers and percent of hatchery sockeye in Columbia River commercial catch. Catcti Brood year Hatchery fish Total catch year Marked Unmarlted Total % all lish 1964 1960 517 1,504 2.021 Total 1961 2 519 8 1,512 10 2.031 9.8 20.770 1965 1960 42 123 165 1961 82 316 398 Total 124 439 563 96 5.843 1966 1961 24 90 114 Total 1962 189 213 638 728 827 941 21,6 4.361 1967 1962 500 1,692 2.192 Total 1963 751 1.251 5.443 7.135 6.194 8,386 14.9 56.220 1968 1963 31 226 257 (') 25.300 'Not applicable as no 1964 brood hatchery frsh were marlted Potential Hatchery Catch A potential hatchery catch figure is a theoretical number that represents what could have been caught in a given fishery assuming the same effort and no marking progi-am and was required to cal- culate benefit/cost ratios. It allows for the large number of fish failing to survive because of the mark. Potential hatchery catch (Table 4) was cal- culated by dividing the number of marks in the catch by the mark survival factor and adding the WAHLE ET AL.: 1960.63 BROOD HATCHERY-REARED SOCKEYE SALMON Table 4. — Potential number and weight of hatchery sockeye by brood year and catch year. Catch year No, with marks in sample Hatchery fish in catch Brood year Estimated no Potential no Potential wt' (kg) 1960 1964 265 2.021 2.359 4.122 Total 1965 22 287 165 2.186 192 2.551 342 4.464 1961 1964 1 10 11 16 1965 43 398 451 802 Total 1966 1 45 114 522 130 592 234 1.052 1962 1966 8 827 950 1.706 1967 191 2,192 2.518 4.085 Total 199 3.019 3,468 5.791 1963 1967 294 6.194 6,684 10.733 1968 16 257 277 479 Total 310 6,451 6.961 11.212 Grand total 841 12.178 13.572 22.519 ' The average weight of commercially caught sockeye ranged from 1 ,5 to 1 .8 kg dunng the study. number of unmarked hatchery fish in the catch: potential hatchery (catch) = n marks (catch) + unmarked hatchery (catch). survival factor ECONOMIC EVALUATION A primary purpose of this study was to deter- mine the economic feasibility of rearing sockeye salmon at Leavenworth National Fish Hatchery. An oft-employed measure of financial worth of a program is the benefit/cost ratio which compares the dollar value (benefit) of the fish returned to the amount spent (cost) in their production. Normally a favorable ratio should exceed 1:1. Cost Accounting Production costs for each brood of sockeye salm- on in this study were derived in the same manner as in Wahle et al. (1974) and consisted of two categories, amortized construction costs or capital costs and operational costs. The "annual imputed capital charge" was com- puted by amortizing the capital expenditures at the hatchery into 30 equal annual payments using an interest rate of S.S'^r . This rate was the average 3- to 5-yr government bond mterest rate weighted by the total annual capital outlay at Columbia River Program Development hatcheries from 1949 to 1970. As the hatchery reared other species inaddition to the study fish, the capital charge was apportioned by applying a percentage based on the ratio of manpower time charged specifically to sockeye salmon care. Operation and maintenance costs were divided into fish food and drugs, and other operational costs. Fish food and treatment costs were appor- tioned according to the pounds of study fish pro- duced as a percentage of the total production. Other operational costs including labor, personal services, travel, equipment, supplies, and ad- ministration were apportioned, as with capital, according to the percentage of time allotted to the care of each brood. Benefits In other economic studies involving Columbia River salmonids ( Worlund et al. 1969; Wahle et al. 1974) benefits included the accrued values from exvessel prices received by commercial fishermen engaged in the variety of catch methods, i.e.. offshore troll, purse seine, gill net, set net, etc. In addition, benefits were calculated for sport-caught fish and for sale of adult carcasses to processors. Our study included only the benefits to commer- cial fishermen on the Columbia River in the gill net (zones 1-5), and tribal dip net (zone 6) fisheries. Sport catch values were not considered as there are virtually no sockeye salmon caught by anglers in the river. The simple exvessel price paid to fishermen is a reasonable estimate of benefits as explained by Richards,- although some inadequacies exist in more intensive and complicated fisheries. For the minor fisherv involved in this studv. this method ^Richards, J. A. 1969. An economic evaluation of Columbia River anadromous fish programs, U.S. Dep. Int.. Fish Wildl, Serv,, Bur, Commer, Fish., Working Pap. 17, 274 p. 237 FISHERY BULLETIN: VOL 77. NO 1 of valuation seemed satisfactory. The commercial price paid to fishermen during the sampling years ranged from $0.68 to $0.82/kg depending on the area of catch. The benefit/cost ratio averaged 0.039:1, or approximately 4 cents returned for each dollar spent (Table 5). Table 5. — Benefit-cost ratios for Leavenworth sockeye 1960-63 broods. Brood year Total calch (kg) Hatchery fish in catch Potential Potential wt (kg) value ($) Pro- duction cost ($) Potential benelit- cost ratio 1960 1961 1962 1963 Total 41.327 49.160 97,228 75.579 263.294 4.464 3.062 1.052 858 5.791 4.456 11.212 8.723 22.519 17.099 114.123 86,823 124.321 113.541 438.808 027 1 010 1 036 1 077 1 039 1 DISCUSSION As our results clearly show, hatchery fish did not appear significantly in the commercial catch, averaging only 13.5% of the total harvest. Consid- ering that the hatchery fish may have utilized almost one-half of the natural rearing space avail- able, we expected their contribution would be greater. We also expected a larger proportion of hatchery fish in the returning adult run based on the ratio of hatchery to wild smolts emigrating from Lake Wenatchee. In a concurrent study, Craddock^ determined that hatchery fish made up 53% and 72% of the 1962 and 1963 total outmigra- tion, respectively. From the economic viewpoint we feel that the study produced an accurate assessment of the ben- efits provided to the commercial fishermen by the addition of hatchery fish to their catch. We are confident that the method of determining the pro- duction costs of the hatchery sockeye salmon pro- vided a valid estimate for that portion of the benefit/cost ratio. Benefits as a measure of value in this study applied specifically to those received by the com- mercial fishery. Not considered were intangible benefits derived from the preservation, mainte- nance, and enhancement of the Columbia River sockeye salmon. The return of adults to the system for a hatchery egg source is another value. Another unmeasured benefit was the contribution to the Indian subsistence and ceremonial fisheries. In short, the total benefits from the Leavenworth ^D. R. Craddock, Northwest and Alaska Fisheries Center. National Marine Fisheries Service. NOAA. Mukilteo. WA 98272, pers. Commun. April 1964. Hatchery sockeye salmon program were obviously greater than the value derived within the specific confines of the study. From the catch results it is apparent that the study period was one of an abnormally low har- vest. The river below Bonneville Dam was closed completely for two of the catch seasons and only 5 days fishing allowed in another, with almost all of the small catch taken in the Indian fishery. As the benefits were based on the number offish provided the commercial fishery, and the zones 1-5 fisher- men were almost completely denied the opportun- ity to harvest these fish, then little in the way of value could be expected under these conditions. It should be noted that the regulatory measures were in effect specifically for the protection of low runs of summer chinook salmon and summer steelhead trout which can be netted at the same time in the area. Another indication of the unusually low harvest of sockeye salmon during the study period is noted in catch/ escapement ratios ( C/E ), which in the 5 yr preceding the study were 1/1 - 2.6/1. During the study the ratio did not exceed 0.5/1 and ranged downward to 0.02/1 (Fish Commission of Oregon and Washington Department of Fisheries 1968). In addition to the low rate of return associated with adult harvest, we suspected that poor surviv- al of the released fish through various stages was a primary cause of low adult returns. Problems con- fronting the young sockeye salmon are discussed below. We could not assess any effect on the released fingerlings caused by rearing practices at Leav- enworth Hatchery, as there was no comparable rearing of sockeye salmon elsewhere. We assumed that the produced fish were of good quality, as the rearing techniques, disease control, and nutrition in effect at the hatchery were essentially the same at other Columbia River salmon hatcheries rais- ing other species. A possible hatchery-related effect on the quality of the stocked fish may have been undetected dis- ease. As reported by Guenther et al. (1959), a filterable virus disease transmitted by feeding of sockeye salmon carcasses at Leavenworth Hatch- ery caused extreme mortalities prior to 1954 when the practice was discontinued. Losses from unde- tected diseases could have had significant effect on survival following release of the fingerlings. Al- though kidney disease was not detected at the hatchery, prior to release, the senior author ob- served it in fish held in saltwater during the mark 238 WAHLE ET AL., 1960-63 BROOD HATCHERY-REARED SOCKEYE SALMON retention phase of the project. Cumulative long- term effects on outmigrants may have been sub- stantial. Other viral diseases, about which little was known at the time, may have been present. Lake Existence A high rate of mortality occurred in Lake Wenatchee during the period of lake rearing, and this was probably spread over the period from stocking until outmigi'ation. Losses similar to the 62 and 51%, found where outmigrants were enum- erated, undoubtedly occurred in the 2 yr in which outmigrants were not counted. Foerster ( 19681 re- ported that the average smolt migration from British Columbia and Alaska lakes where only fry were stocked was 44% and the survival to return ranged from 11 to 84% . The hatchery rearing at Leavenworth seemed an economic waste, as equal outmigration rates may have been obtained using fry plants. There is an extensive sport fishery in Lake Wenatchee on Dolly Varden, Sa!ve!iiu/s malma, and kokanee, a nonmigrant strain of sockeye salmon. We monitored this fishery in order to de- termine the effect on released study fish. Incidental to the trout catch, a fairly large number of sublegal ( <6-in) hatchery salmon were taken. This was determined by the presence of marked fish in a sample of sublegal fish in the angler catch. The hatchery fish were caught dur- ing the early spring of their second year just prior to their outmigration. Most sublegals were re- leased by the anglers, but mortality undoubtedly resulted from hooking and handling. Addition- ally, some of the marked sockeye salmon remained in the lake without migrating and were observed throughout the season in the creel checks of legal- sized trout. The percentage becoming resident was unknown, but in 1964 represented 1.4% of the calculated total kokanee sport catch of 17, 523 fish. Sockeye salmon becoming resident in the lake and entering the sport fishery, based on 1964 data, accounted for <1% of the stocked fish. The mortal- ity of sublegal fingerlings from angling was as- sumed to be small because of their rare occurrence in the sport catch. Health records of the hatchery fish did not indicate any expected loss from disease or parasites. Undoubtedly, the large loss of finger- lings was due to predation by larger fish and possi- bly starvation. The heaviest loss of fingerlings in the lake was certainly caused by predation. Although precau- tions were taken during release, when fish were barged to avoid shoreline concentrations. Thompson and Tufts (1967) reported heavy preda- tion both during and following release periods. Dolly Varden and northern squawfish, Ptychocheilus oregonensis, were sampled by gill net and trolling gear. Dui-ing the weeks of release, the number of captured fish containing sockeye salmon ranged from 58 to 100% . Gangmark and Fulton (1952) during experiments in 1949-51 re- ported heavy predation by the same species. Our own observations of angler-caught fish from March through July 1962 showed an average of over one sockeye salmon per stomach. No estimate of the total predation loss was possible as the total number of predators was not known. From our observations and those reported by Allen and Meekin (1973) the zooplankton produc- tion in the lake peaked in August and September each year. The hatchery fish, stocked in October, were faced with a declining food supply. Growth apparently stopped during the winter. Fingerlings of the 1961-brood averaged 97 mm FL when stocked in October whereas in the following spring, migrants trapped at the outlet, had a size range of 87-98 mm FL (Weber and Wahle 1969). Low food productivity of the lake, coupled with competition from natural resident fish for food, undoubtedly affected the fitness of the migrant sockeye salmon and possibly caused subsequent losses from stress on the seaward journey. It is highly improbable that any hatchery pro- duction program utilizing an additional rearing period in Lake Wenatchee could succeed. How- ever, even if no loss had occurred during lake resi- dence, thus doubling the number of hatchery out- migrants, no more than a twofold increase in adults could be expected. Even with such an im- provement, still more than 10 times that number of adults would be required for a favorable benefit/cost ratio. Downstream Migrant Problems With a large portion of the production sacrificed in the lake, the remaining smolts were still faced with gi-eat problems. Until recently, little was known of the causes and extent of downstream losses of sockeye salmon, although much informa- tion has been obtained for chinook salmon and steelhead trout smolts. Anas and Gauley 11956) studied the seaward migration of sockeye salmon smolts and their data suggested a wide range in 239 FISHERY BULLETIN: VOL 77, NO. 1 travel time and in size and age of migi'ants. No estimates of mortality of any given gi-oup of sock- eye salmon could be made from their data or from other studies conducted at the various dam proj- ects. However, we have assumed that extremely large losses occur in each annual outmigration of sockeye salmon, comparable to those documented for Chinook salmon and steelhead trout. Losses can occur in but a short distance during the seaward journey. Ellis and Noble (1960) re- ported losses of fall chinook salmon of 12.2 to 29.7% in the Klickitat River in a distance of only 64 km. The Wenatchee stock sockeye salmon smolts had to navigate 844 km in their seaward migration and were subjected to injuries and pos- sible death at each of seven dams, plus the myriad effects of altered flows and water quality. Major direct causes of mortality in juvenile mi- grants are gas bubble disease, a result of high dissolved nitrogen concentrations which occur throughout the river and death or injury by pass- ing through turbines (Ebel et al. 1973). At high flows with excessive spill the fingerlings are sub- jected to the nitrogen problem, while the turbine caused losses are most severe at low flows. Chaney and Perry ( 1976) reported that the juvenile losses averaged 15 to 20% at each mainstem dam from combined causes. At low flows, cumulative fish losses just from turbine mortality at a series of seven dams may exceed 90'/f . Additional mortality can be expected from sev- eral other causes. The delay of stream flow in the impoundments has reduced migration rates of juveniles by one-third according to Raymond (1969). The fish are then subject to increased pre- dation, possible loss of marine adaptability, and may become residual in the reservoir. Undoubt- edly but a small part of the outmigrants ever reach the sea in some years. Adult Problems We surmise that the sockeye salmon suffer loss- es comparable to the other species in the ocean, but there is no appreciable fishery harvest. The few tagging returns that have been reported for Co- lumbia sockeye salmon (Margolis etal. 1966) indi- cate a more southerly distribution than for Cana- dian or Washington sockeye salmon, and there is no inshore marine fishery to intercept the adults. The relatively few remaining adult sockeye salmon, after surviving the perils of sea life, still must face serious obstacles on the spawning mi- gration. Aside from the commercial harvest, a substantial mortality occurs which cannot be measured precisely. In early reports of upriver fish passage, Schoning (1948) pointed out that annu- ally an average of 36% of the Bonneville Dam count could not be located after subtracting the known harvest. "Fall-back" contributes to the loss and obscures the actual number passing the dam. Later accounts corroborate these losses (Chaney and Perry 1976). Bonneville Dam mortalities would reduce the number offish available for har- vest only in the zone 6 portion of the fishery. SUMMARY 1. The Columbia River system produced large runs of sockeye salmon prior to 1900, providing an annual commercial harvest reaching 2 million kg. 2. Deterioration of spawning areas and blockage of tributaries caused a severe decline in the sock- eye salmon population early in this century. 3. Construction of Grand Coulee Dam in 1941 blocked the sockeye salmon from 1,835 km of spawning and rearing areas, virtually eliminat- ing all natural production. 4. Compensatory measures intended to replace the lost production included relocation of the sock- eye salmon runs to suitable areas below Grand Coulee Dam and construction of hatcheries for additional production. 5. Leavenworth National Fish Hatchery on the Wenatchee River was activated in 1940 as the primary fish production station and an annual stocking program of sockeye salmon fingerlings was started. 6. For over 20 yr Leavenworth Hatchery reared sockeye salmon, releasing the fingerlings into the Wenatchee system augmenting the natural pro- duction. 7. No assessment had been made of the actual contribution of hatchery fish to the commercial fishery, thus the subject study was initiated using the 1960-63 broods of sockeye salmon. 8. During the initial 4 yr of the study, a total of 11,538,291 fish were released, of which 3,390,941 were marked by removal of the adipose fin and a part of the maxillary bone. 9. The stock used was adult .sockeye trapped in tributaries of Lake Wenatchee. Fingerlings were reared at the hatchery until fall, then released into Lake Wenatchee. 10. Surviving smolts migrated out of the lake in the spring. Outmigrant trapping in the first 2 yr 240 WAHLE ET AL : 1960-63 BROOD HATCHERY-REARED SOCKEYE SAI \ION revealed that <50^ of the stocked fish migrated downstream. 11. From 1964 through 1968, sampling for marked adults was conducted in the two Columbia River fisheries: the gill net area below Bonneville Dam (zones 1-5), and the Indian set net and dip net fishery above the dam (zone 6). An average of 43.5% of the commercial catch was examined for marks. 12. The commercial harvest was atypical during the study because of regulation restrictions. The average annual harvest for the period was only 22,500 fish compared with average landings of 90,900 for the prior 7 yr. The C/E ratio did not exceed 0.5/1. 13. Almost all hatchery fish in the catch were in their fourth year of life. The average weight offish in the catch ranged from 1.5 to 1.8 kg. 14. A mark mortality correction factor was in- cluded in calculations of hatchery fish in the catch as it was shown that the marked fish survival was only 60.52'^f of the unmarked fish. 15. During the study, hatchery fish composed an average of 13.6% of the total commercial catch. 16. The exvessel price to fishermen, used to de- termine benefits in this study, ranged from $0.68 to $0.82/kg. 17. Production costs were determined by a pre- viously developed method utilizing both capital and operational charges. 18. The benefit cost ratio for the study broods was 0.039:1 or about 4 cents returned for each dollar spent. 19. Factors contributing to poor survival of juvenile fish were: high mortality from predation and angling during lake rearing, probable disease and nutritional problems, losses during migration from turbine injury and gas bubble disease, and delay in reservoirs. 20. Reasons for the low return of adults to the fishery include: unknown ocean mortality, losses incurred while ascending Bonneville Dam, and the erratic opportunity of harvest because of sea- son restrictions. ACKNOWLEDGMENTS We are grateful for the assistance and coopera- tion of various individuals and agencies during the course of this study. Special thanks are offered the following individuals: Donald D. Worlund, National Marine Fisheries Service, for develop- ment of design and acting as primary consultant; Douglas Weber, Donovan Craddock, and Robert McConnell, National Marine Fisheries Service; Paul D. Zimmer and Eugene Maltzeff, Bureau of Commercial Fisheries; John W. Kincheloe and Steven K. Olhausen, U.S. Fish and Wildlife Service; and Arthur L. Oakley, formerly Fish Commission of Oregon, for their assistance in the design, supervision, and data collection and pro- cessing portions of this study. The aid and cooper- ation of Alfred C. Gastineau and Fredrick W. Bitle and staff of Leavenworth National Fish Hatchery is much appreciated. Helpful editorial comments were contributed by Richard T. Pressey, John I. Hodges, Steve H. Smith, National Marine Fisheries Service; William Sholes, California De- partment of Fish and Game; Robert Foster, Washington Department of Fisheries; Frederick C. Cleaver, Columbia River Fisheries Council; and F. K. Sandercock, Canadian Fisheries and Marine Service. Our thanks are due Kathleen LaBarge and Vivian Dignan for typing the text and tables for this publication. LITERATURE CITED ALLEN, R. L.. AND T, K, MEEKIN, 197.3. ColumbiaRiversockevesalmonstudy. 1972. Prog. Rep. Wash. Dep. Fish,. 61 p. ANAS, R. E.. AND J. R. GAULEY. 1956. Blueback salmon, Oncorhynchus nerka age and length at seaward migration past Bonneville Dam. U.S. Fish Wildl. Serv.. .Spec. Sci. Rep. Fish. 185. 46 p. Chaney, E., and L. E. Perry. 1976. Columbia Basin salmon and steelhead anal- ysis. Summ. Rep., Pac. Northwest Reg. Comm., 74 p. CRAIG. J. A., and R. L. H.ACKER, 1940. The history and development of the fisheries of the Columbia River. Bull. |U,S.] Bur. Fish, 49:133-216. Ebel, W. J,, D, L. Park, and R, C. Johnsen, 1973, Effects of transportation on survival and homing of Snake River Chinook salmon and steelhead trout. Fish, Bull,, U,S. 71:549-563, Ellis. C. H., and R. E, Noble, I960. Barging and hauling experiments with fall chinook salmon on the Klickitat River to test effects on survivals. Wash, Dep, Fish., 70th Annu. Rep., p. 57-71, Fish Commission of OREtMjN and Washington Depart- ment OF Fisheries, 1968. The 1967 status report of the Columbia River com- mercial fisheries. Fish, Comm. Oreg. and Wash. Dep. Fish.. 91 p. Fish. F. F,. and M, G, Hanavan, 1948, A report upon the Grand Coulee Fish-Maintenance Project 1939-1947. U.S. Fish Wildl. Serv., Spec, Sci, Rep, 55, 63 p, FOERSTER. R, E, 1968. The sockeye salmon, Oncorhynchus nerka. Fish. Res. Board Can.. Bull. 162, 422 p. 241 FISHERY BULLETIN: VOL. 77, NO 1 French, R. R., and R. J. Wahle. 1959. Biology of Chinook and blueback salmon and steelhead in the Wenatchee River System. U.S. Fish Wild). Serv., Spec. Sci. Rep. Fish. 304, 17 p. 1965. Salmon escapements above Rock Island Dam, 1954-60. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 493, 18 p. Fulton, L. a. 1970. Spawning areas and abundance of steelhead trout and coho, sockeye, and chum salmon in the Columbia River basin — past and present. U.S. Dep. Commer., Natl. Mar. Fish. Serv., Spec. Sci. Rep. Fish. 618, 37 p. GANGMARK, H. a., and L. a. FULTON. 1952. Status of Columbia River blueback salmon runs, 1951. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 74, 29 p. GUENTHER, R. W., S. W. Watson, and R. R. Rucker. 1959. Etiology of sockeye salmon "virus" disease. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 296, 10 p. KOSKI, R. O. 1964. Management of migratory game fish. Oreg. State Game Comm., Bull. 19(6), 8 p. Major, R. L., and d. r. craddock. 1962. Influence of early maturing females on reproductive potential of Columbia River blueback salmon lOncorhyn- chus nerka). U.S. Fish Wildl. Serv., Fish. Bull. 61:429- 437. Margolis, l., f. C. Cleaver, Y. Fukuda, and H. Godfrey. 1966. Salmon of the north Pacific Ocean — Part VI. Sock- eye salmon in offshore waters. Int. North Pac. Fish. Comm., Bull. 20, 70 p. Raymond, H. L. 1969 Effect of John Day Reservoir on the migration rate of juvenile chinook salmon in the Columbia River. Trans. Am. Fish. Soc. 98:513-514. SCHONING, R. W. 1948. Trends of Columbia River blueback salmon popula- tions 1938-1947. Fish Comm. Greg., Res. Briefs l(2):33-40. THOMP.SON, R. B., AND D. F. TUFTS. 1967. Predation by Dolly Varden and northern squawfish on hatchery-reared sockeye salmon in Lake Wenatchee, Washington. Trans. Am. Fish. Soc. 96:424-427. Wahle, R. J., R. R. Vreeland, and R. H. Lander. 1974. Bioeconomic contribution of Columbia River hatch- ery coho salmon, 1965 and 1966 broods, to the Pacific salmon fisheries. Fish. Bull., U.S. 72:139-169. Ward, D., R. robison, and a. Palmen. 1963. 1963 fisheries statistical report. Wash Dep Fish., 73d Annu. Rep., p. 127-216. Weber, D., and R. J. Wahle. 1969. Effect of finclipping on survival of sockeye salmon iOncorhynchus nerka). J. Fish. Res. Board Can. 26:1263-1271. Worlund, D. D., R. J. Wahle, and P. D. zimmer. 1969. Contribution of Columbia River hatcheries to har- vest of fall chinook salmon iOncorhynchus tshauytscha). VS. Fish Wildl. Serv., Fish. Bull. 67:361-391. 242 RELATIVE ABUNDANCE, BEHAVIOR, AND FOOD HABITS OF THE AMERICAN SAND LANCE, AMMODYTES AMERICANUS, FROM THE GULF OF MAINE Thomas L. Meyer, Richard A. Cooper, and Richard W, Langton' ABSTRACT Meristic characteristics of sand lance taken from Stellwagen Bank indicated the species to be the American sand \ance, A mmodytes a menvanus. Bottom trawl data, ichthyoplankton surveys, and diver and submersible observations demonstrated a significant increase in relative abundance of sand lance since about 1975 on Stellwagen Bank; this trend was typical of the Northwest Atlantic from Cape Hatteras. N.C., to the Gulf of Maine. School shapes were constant in appearance, vertically compres- sed, tightly compacted, and bluntly linear from a dorsal and ventral view. School strengths varied from about 100 to tens of thousands of individuals with the nearest-neighbor distance ranging from '/* to 1''2 body lengths. The swimming motion is sinusoidal in form and eellike in appearance. Swimming speeds varied from 15 to over 120cmy's. Copepods were the most important food source, constituting 4 l*^f of the total weight of food consumed; sand lance feed in school formation between midwater and the surface. Sand lance bury themselves totally or partially in clean sandy substrates when not schooling. In the Northwest Atlantic, sand lance range from Cape Hatteras, N.C., to Hudson Bay. They occur over sand and fine gravel bottoms and play an important role as a trophic Imk between zoo- plankton and commercially important fish such as Atlantic cod, haddock, silver hake, and yellowtail flounder (Scott 1968, 1973; Bowman and Langton 1978). Several species of sportfish (e.g., striped bass and bluefish) also utilize the sand lance as a food source (Bigelow and Schroeder 1953). Studies of the eggs, larvae, and postlarvae of the American sand lance, Ammodytes americanus. have been reported by Covill (1959), Richards (1959, 1965, 1976), Norcross et al. (1961), Wil- liams et al. (1964), and Richards and Kendall ( 1973). Investigations on the adult sand lance in- clude taxonomic studies by Backus (1957), Richards et al. ( 1963). Leim and Scott (1966), Reay (1970), Winters (1970), Scott (1972-), and Pelle- grini^ and studies on mortality and growth by Graham ( 1956) and Pellegrini (see footnote 2). De- spite these investigations, little is known about the relative abundance, biology, behavior, and food habits of the adult American sand lance. 'Northeast Fisheries Center Woods Hole Laboratory, Na- tional Marine Fisheries Service, NOAA, Woods Hole. MA 02543. 2Pellegrini,R. 1976. Aspectsofthebiology of the American sand \ance, Ammodytes ariiencanus. from the lower Merrimack River estuary, Massachusetts. Master's problem, Univ. Mas- sachusetts, Amherst, 44 p. Manuscript accepted September 1978 fishery bulletin vol 77. NO 1. 1979 For the last 10 yr, information has been col- lected on sand lance during fishery cruises and undersea research programs conducted by the Northeast Fisheries Center, National Marine Fisheries Service, NOAA, Woods Hole, Mass. The purpose of this paper is to describe some aspects of the abundance, behavior, and food habits of the American sand lance based on bottom trawl (groundfish) survey data, observations by scuba divers and from research submersibles with photographic records, and a food-habit study. MATERIALS AND METHODS Study Area The majority of the observations on sand lance were made on Stellwagen Bank, a submarine ridge that rises to within 18 m of the ocean surface on the eastern boundary of Massachusetts Bay (Figure 1). The length of the bank is 39 km (north-south axis) and its greatest width is 13 km (at the southern end). Depths range from 18 to 77 m. Substrate characteristics by depth interval re- corded during submersible operations are: 18-43 m — sandy; 43-55 m — sandy bottom with crushed shells; 55-77 m — gravel, rocky with boulders; and below 77 m — mud/silt. Approximately 95'7c of the bank has a sandy bottom. Additional observations on sand lance were 243 FISHERY BULLETIN: VOL. .NO. 1 Table 1. — Dive locations on Stellwagen Bank and Cape Coc (Provincetown. Mass.) with observations' on presence ( + ) or absence 10) of American sand lance. Observations were made using scuba and submersible (sub). FUILIRE 1. — Study area of sand lance observations. Gulf of Maine. made on the Provincetown slope from Race Point to Wood End (Figure 1). Depths over the Province- town slope range from to 46 m, with a medium- coarse sandy substrate throughout the range. Slope gradients by depth interval are: 0-9 m — 5°- 15°; 9-46 m— 30°-45°. The relatively steep slope begins between 90 and 250 m offshore. Relative Abundance Divers using scuba, or observers in submersi- bles,^ made in situ observations during various manned undersea research projects from 1968 through 1977 (Table 1, Figure 2). Camera systems aboard the submersible were: 1) a 35-mm Nikon'' camera using a 55-mm micro lens and an exter- nally mounted MK 150 Subsea stroboscopic light, and 2) a Sony AD 3400 Monochrome video camera and recorder. Dive sites Dales ol Provincelown Stellwagen Banl( observations Scuba Sub Scuba Sub 1968 1 -0 1216 July - scuba 2 1969 1 21-25 July - scuba 2 3 1970 1 5 - 06-09 July - scuba 2 3 6- 1971 1 8 - 4 1 -0 23-25 June • scuba 2 9 - 2 22 Sept sub 3 10- 3 4 5 6 7 1972 1 -0 4-0 18-21 July - scuba 2-0 5 24-31 Ocl • scuba 3 60 1973 1 - 7 1 05-10 Ocl - scuba 2 - 8- 2 05-09 Ocl • sub 3 9 - 3 10 - 4 11-0 5 12- 6 7 8 9 10 1974 1 06-11 July scuba 2-0 3 1976 1 - • 1 f-t 16-18 June - scuba 2 - ^ * 2- + 15-18 June • sub 3- . + 1977 1 - t + + 4 -t--f 08-11 Aug scuba 2 --)--)- -f 3- + + -¥ 5 ■f-f 'Estimates of relative abundance are noted as for no sightings, ' lor a lew sand lance observed. • • for small schools (several hundred individuals per school) with infrequent sightings, and ^ + ^ for large schools (thousands per school) and schools observed almost continuously Stellwagen Bank is included in one of the sam- pling strata covered by the spring and fall bottom trawl surveys since 1963 (Grosslein 1969). This stratum encompasses the Massachusetts Bay area, extending from Provincetown to Cape Ann and ranges in depth up to 110 m (Figure 1). Sta- tions were selected randomly within the stratum for each survey and the number of stations actu- ally occupied on Stellwagen Bank on each survey ranged from to 6. Trawl survey results are pre- sented only for 1967-77, the period during which diver and submersible observations were made. Behavior ■^Research submersibles were chartered by NOAA's Manned Undersea Science and Technology Program, Rockville, Md. ■•Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. Photographic and video records of sand lance behavior were made by scuba divers during a hy- droacoustic experiment from RV Albatross IV, 244 MEYER ET AL AMERICAN SAND LANCE FROM THE GULF OF MAINE Figure 2. — Dive sites and location of 1977 food habits study on Stellwagen Bank and Cape Cod (Provincetownl from 1968 to 1977. Scuba (lines), sub- mersible (dotted lines), 1977 bottom trawl (hatching) sampling areas. See Table 1 for key. (972- 1974 FOOD HABITS STUDY \ ^ m^ v- 8-11 August 1977, on Stellwagen Bank (scuba dive locations 4, 5) and along the Provincetown slope (scuba dive locations 1-3) (Figure 2C)., Divers, using a Hydro-Products Model 125 tele- vision system with a 250-W thallium-iodide light source, filmed sand lance behavior on and near the bottom. The angles and speed at which sand lance entered the bottom substrate and exited from it were estimated from slow-motion video playback. Schooling behavior was observed and photo- graphed using a Nikonos II underwater camera with a 28- or 35-mm lens and a Subsea MK 150 or 225 electronic strobe. School strength, shape, nearest-neighbor distance, and individual fish size were estimated using in situ observations, photo- graphs, or bottom trawl data. School swimming speeds were estimated at approximately 1 kn by divers swimming parallel to several schools for short distances. A speed of 1 kn is the approximate short-term sustained swimming speed of a diver. All in situ observations by diver scientists were made in daylight between 0900 and 1600 h. Food Habits A series of nine tows were conducted from Al- batross IV on the southwestern edge of Stellwagen Bank over one 24-h period beginning at 1800 h on 9 August 1977 (Figure 2D). The tows were of 5-15 min duration at 3-h intervals and were made with 245 FISHERY BULLETIN: VOL, 77, NO, 1 a Yankee #36 trawl (Grosslein^). The cod end and upper belly of the net were lined with 13-mm mesh netting, knot to knot. Only three species of fish were caught in any quantity: spiny dogfish, Squalus acanthias; silver hake, Merluccius bilinearis; and American sand lance. Sand lance were taken at random from the catch and pre- served whole in lO'^f Formalin for stomach- content analysis. In the laboratory, the stomachs were dissected out for stomach-content analysis. Ten fish from each of the nine tows were randomly selected from the preserved specimens for analysis. After the stomach was removed from each fish, the contents were examined and washed onto a fine-mesh screen. If the stomach appeared empty or had trace amounts (<1.0 mg) of food in it, it was rinsed out with seawater directly into a Petri dish. When there was a weighable quantity of prey present, the excess water was drawn off by pressing an absorbent tissue paper to the underside of the screen; the contents were weighed and then washed into a Petri dish. Using a dissecting micro- scope, the prey of each fish were identified to the lowest possible taxonomic grouping, and the per- centage composition of each of the identified groups estimated. The percentage composition and total stomach-content weight were used to calculate the percentage weight for each prey category. The data were also expressed in terms of the percentage occurrence of each prey group in the stomachs. from 30 to 31 with a mean of 30.7, SD = 0.48. The dorsal fin ray count ranged from 60 to 63 with a mean of 61.1, SD = 0.99. The vertebral count, based on radiographs of 20 fish and excluding the hypural complex, ranged from 67 to 72 and aver- aged 69.25, SD = 1.21. The mean values reported here fell into the A. americanus category given by Reay (1970). For the purpose of this paper, the classification of Reay (1970) is accepted. Relative Abundance Examination of spring and fall survey data for the past 10 yr, excluding 1967, 1969, 1971, and 1973 for spring and 1971 and 1977 for fall (Stell- wagen Bank stations were not sampled), indicates a substantial increase in sand lance abundance on Stellwagen Bank (Figure 3). The relative abun- dance increased during spring cruises from virtu- ally for the 1967-75 period to 50/tow in 1976 and 10,729/tow in 1977, while increasing during fall cruises from for the 1967-74 period to 4,238/tow in 1975 with a decrease to 5/tow in 1976. Spring cruises (March- May) may give a better indication of sand lance abundance since fall cruises are con- ducted from October to December, a period of les- ser sand lance activity before spawning ( Winslade 1974). In the Gulf of Maine, all bottom trawl sur- vey catches <75 sand lance/tow occurred on or along the edge of Stellwagen Bank. The catch rate RESULTS AND DISCUSSION In the taxonomic studies listed above, mor- phometric and meristic characteristics were used to distinguish between "inshore sand lance" [Ammodytesai7iericaniis -Ainmodytes hexapterus ) and "offshore sand lance" (Ammodytes dubius), although Bigelow and Schroeder (1953) ques- tioned whether such a distinction could be made. Because of the question regarding the taxonomic status of A. americanus and A. dubius. several meristic characteristics were evaluated on sand lance caught on Stellwagen Bank (Figure 2D). Dorsal and anal fin ray counts were made directly on 10 randomly chosen fish ranging from 17.9 to 22.2 cm fork length (FL) and averaging 20.0 cm, SD = 1.24. The anal fin ray count ranged 10.000 9000 J 6000 4000 SOOO 900 ' 700 , 500 : soo SPRING BOTTOM TRAWL SUBVET FALL BOTTOM TRAWL SURVEY -A/- NOSAMPLE COLLECTED oyv= 1967 ■=!^ V=^ ^Grosslein, M. D. 1969. Groundfi.sh survey methods, >fMFS, Woods Hole, Massachusetts. Lab. Ref. No. 69-02, 34 p, 246 Figure 3. — Catch of adult sand lance per standard tow on Stell- wagen Bank during the NMFS .spring and fall bottom trawl stratified sampling surveys for 1967-77. MEYER ET AL AMERICAN SAND LANCE FROM THE GULF OF MAINE declined drastically, to <1 sand lance/tow, when not fishing on the bank. In the southwest North Sea, fishermen have also noticed that better catches occur along the edges of larger banks and on the tops of smaller ones (Popp Madsen 1963). In the last 10 yr, sand lance have shown evi- dence of a population increase along the Atlantic coast from Cape Hatteras, N.C.. to and including the Gulf of Maine. Northeast Fisheries Center spring and fall bottom trawl survey results from 1968 to 1977 show large annual fluctuations in sand lance abundance since 1968 with a definite upward trend beginning in 1975 (Figure 4). The magnitude of this increase is considerably less than that recorded on Stellwagen Bank for the same period, but the yearly trends are similar. One area of concern in attempting quantitative sampling is net avoidance. Livingstone (1962) documented on film that adult sand lance were able to escape in <2.5 s from the cod end of a Yankee Modified #41 trawl net with a cod end mesh of 1 14 mm, knot to knot, and a -SS-mm cotton webbing covering. These films also showed the ease with which individuals and small schools were able to avoid the trawl net. In areas where abundance is high, the ability to avoid trawl nets maybe less effective. Scott ( 1973) found it unusual to catch adult sand lance in nets except in areas where they were very abundant. Relative abundance of sand lance on Stellwagen Bank and Provincetown slope, based on diver and submersible observations, has increased sig- nificantly since 1976 (Table 1). Although numer- - SPRING BOTTOM TRflWL SURVEr - fALL eoT TOM TRflWL SUftVE » Figure 4. — Changes in the relative abundance of adult Ammo- dytes spp. in the Northeast Fisheries Center spring and fall bottom trawl surveys from 1968 to 1977 in the area extending from Cape Hatteras northward. (Data from Grosslein et al. in press, table 3.2.) ous diving programs have been carried out over the study area since 1968, it was not until the spring of 1976 that .schools of sand lance were first observed. However, it is very likely that relatively small numbers of sand lance were present in the study area prior to 1976 but not noticed by the divers. This increase in sightings coincides with an increase in number of sand lance caught per tow during the bottom trawl survey cruises. Sand lance larvae studies, conducted by the Bos- ton Edison Company^ showed sand lance larvae were among the most abundant fish larvae occur- ring in ichthyoplankton sampling surveys con- ducted in Cape Cod Bay, Mass., d.'ring 1974-77. They were more abundant in the eastern portion of the bay and were considerably more abundant in 1976 than in the previous 2 yr. This mcrease in sand lance larvae was also observed during the Northeast Fisheries Center spring ichthyo- plankton surveys conducted in the area from Cape Hatteras to the Gulf of Maine for the past 4 yr (Figure 5). For example, the mean sand lance catch/10 m^ area in spring 1977 was 9 times great- er than in spring 1974. Bottom trawl survey results, diver and submer- sible observations, and ichthyoplankton survey results all indicate that there is a relatively large concentration of sand lance inhabiting a small section of the Gulf of Maine, i.e., Stellwagen Bank and outer Cape Cod (Provincetown slope), and that this population has increased considerably since 197.5; this increase in population is typical of the Northwest Atlantic from Cape Hatteras to the Gulf of Maine. Behavior School Structure Schools of sand lance observed on the Province- town slope were relatively small in numbers of fish, ranging from about 100 to several thousand individuals and were usually found in depths ranging from 6 to 20 m. From photographs it was calculated that individual fish on Provincetown slope ranged from approximately 12 to 17 cm long, with a mean of 15 cm. Sand lance schools observed on Stellwagen Bank were relatively large in num- bers, ranging from about .500 to tens of thousands 'Boston Edison Company. 1974-77. related to operation of Pilgrim Station. Boylston Street, Boston. MA 02199. Marine ecology studies Boston Edison Co., 800 247 FISHERY BULLETIN: VOL 77. NO I 700 600 500 400 300 I 00 - 90 80 - 70 - 60 50 - 40 30 20 Figure 5. — Changes in the relative abundance of larval Am- modytes spp. in the Northeast Fisheries Center spring ichthyo- plankton surveys from 1974 to 1977 in the area extending from Cape Hatteras northward. Data from Smith, W. G.. and L. Sulli- van. 1978. Annual changes in the distribution and abun- dance of sand lance. Ammodytes spp., on the northeastern continental shelf of the U.S. from the Gulf of Maine to Cape Hatteras. Northeast Fish. Cent.. Sandy Hook Lab., Sandy Hook, NJ 07732. Lab. Ref No. SHL 78-22. of individuals. Individuals varied from 7.4 to 24.0 cm FL (measurements from bottom-trawl catches), with a mean length of 18.2 cm. Sand lance within a given school were of similar size; slightly larger fish were observed in positions at the head or central "core" of the school, with the smaller individuals occurring at the periphery. This distribution by size within the school was observed in both study areas. Schools were ob- served on the surface, at mid-depth, and near the bottom. Inshore school strengths described by Kiihlmann and Karst (1967) for European sand lance species Hyperoplus lanveolatus and Ammo- dytes lancea were commonly 30-100 or 200-300 individuals. These smaller schools joined up to form schools of from 500 to > 1 ,000 fish and headed offshore for deeper water in the early morning. We observed schools of this size primarily in the Prov- incetown slope area. However, because the indi- vidual size of the fish and school strengths on Stellwagen Bank were larger, it is unlikely that these schools formed in the Provincetown slope area and moved out to the bank. 248 .ScIkkiI Shape The shape of sand lance schools, where indi- viduals were not engaged in feeding, was constant in appearance. As a school moved undisturbed through the water it appeared vertically compres- sed, tightly compacted, and bluntly linear from the lateral view (Figure 6). Provincetown slope schools were 1-5 m wide, 0,5-1,5 m high, and 3-20 m long; these measurements depended on school strength. This school form, where the height- width-length ratio was approximately 1 :3: 10 ( hav- ing more individuals situated ahead, alongside, and behind than above or below), is called a strat- ified school iWahlert and Wahlert 1963). This school formation was, in general, independent of .school strength. The "nearest-neighbor" distance between fish was approximately '/■!-% body length (BL) (Figure 6), This distance became greater along the school's flanks. The "nearest-neighbor" distance decreased to '4 BL when the school exhib- ited a fright reaction to divers. The fishes leading the school and ones along the flanks usually swam the deepest. School shapes described by Kiihlmann and Karst (1967) were similar to the measurements reported in this study, but a sig- nificant difference appeared in the school height and length measurements. Kiihlmann and Karst (1967) listed their school height as 15-50 cm, and their school length as s40 m. Sand lance schools encountered in our study were more than double the height and shorter in length. The European study took place in water depths of 1-6 m. and in this relatively shallow water, there may be a ten- dency for a school to flatten out and increase its length, Moxement The swimming motion of sand lance is sinusoi- dal in form and eellike in appearance from the dorsal and ventral views. Sidewise undulations begin at the head and run along the body toward the tail (Figure 7). Schools swimming undis- turbed, and not engaged in feeding, maintain an estimated speed of 30-50 cnVs. Schools exhibiting feeding behavior usually swim at about half the speed of undisturbed schools, or about 15-25 cm,s, and spread out to a little over double the normal schooling distances so that the nearest neighbor is approximately l-l'/2 BL away. Smaller schooling groups were observed to swim faster than larger schools. When approached by divers, schools ac- MEYER ET AL : AMERICAN SAND LANCE FROM THE GULF OF MAINE Figure 6. — School of sand lance encountered on Provincetown slope. Note lateral view of sand lance leaving the bottom to join school above. celerated to one side or split to avoid the divers at the part of the school closest to the divers. The forward portion of the school continued on in its original direction, while the rear portion gener- ally reversed direction. These avoidance maneu- vers were made at about 70-120 cm/s, over double the original undisturbed speed, and lasted for only a few seconds before the divided sections re- grouped and slowed down to their original speed. Feeding schools were observed in midwater and near the surface, but not on the bottom. Kiihlmann and Karst (1967) recorded the es- cape speed of larger sand lance to be 300-500 cm/s for at least a few seconds. During our study, there were many occasions when the swimming speed appeared to be >120 cm/s, but the actual speed was not calculated. Behavior Within and Near the Ocean Floor Sand lance were found in substrates conducive to burrowing, such as clean sandy bottoms, sand bottoms with crushed shells, and fine-graveled bottoms. Substrates of mud, mud/silt, medium to coarse gravel, and rock/boulder were avoided. This preference for loose porous substrate facilitates entry and exit and may relate to a sufficient supply of dissolved oxygen within at least the first few- centimeters of interstitial water. Oxygen is con- tinually replenished by tidal currents of 32-47 cm/s (0.62-0.91 kn) measured at 1 m above the bottom on Stellwagen Bank (Padan 1977). Sand lance usually disappear into the bottom in small groups. The initial penetrating angle was estimated as 60°-75° from the horizontal and con- 249 FISHERY BULLETIN VOL 77. NO. 1 < I a a 250 MEYER ET AL.; AMERICAN SAND LANCE FROM THE GULF OF MAINE sisted of a continuance of their sinuous movement until one-quarter of the body was buried, at which point the remaining three-quarters of the body was brought to a 20°-40'' angle to allow the animal to settle into its normal resting position ( Figure 7 ). Once in a resting position, the sand lance would partially emerge headfirst if disturbed (Figure 7). Sand lance on Stellwagen Bank, exhibiting this partial-emergence behavior, would retract back into the bottom when further disturbed. In con- trast, sand lance encountered along Provincetown would usually leave the substrate. Kiihlmann and Karst (1967) observed similar behavior and noted on several occasions that, after pulling back into the bottom, sand lance could turn, move laterally through the substrate, and emerge some distance away. This behavior was not observed in our study area. Sand lance leaving the bottom exited at an angle between 20° and 60° with an initial speed of 50-80 cm/s, which increased up to 120 cm/s within the first 1.5 m from the bottom (Figure 7). As divers proceeded along the bottom, sand lance would exit from the substrate and either school or swim to the end of the diver's visual range. Food Habits The results of the stomach-content analysis for A. americanus collected on Stellwagen Bank are given in Table 2. The data are presented as both the percentage occurrence of prey in the stomachs and as the percentage weight of the total prey consumed. It is evident that copepods were the most important prey, occurring in 37.8% of the stomachs examined and making up 41.4% of the total weight of the prey. The other identifiable prey groups, such as hyperiid amphipods, mysids, euphausiids, chaetognaths, salps, and animal eggs, were much less important, usually occurring in only 1-2% of the stomachs. Of these gi'oups only the chaetognath Sagitta contributed significantly to the diet on a percentage weight basis (39.9% ). This was because the stomach of one fish was quite distended with chaetognaths. "Animal remains," which are unidentifiable prey, were the most fre- quently occurring prey category; however, on a weight basis they were much less significant. The food habits of a number of different species of sand lance have been studied in Atlantic and Pacific waters. In general the diets are all very similar, with copepods being the major prey in almost every instance (Reay 1970). Around Japan, TABLF> 2. — Stomach contents of American sand lance collected on Stellwagen Bank, August 1977. The data are expressed as both the percentage frequency of occurrence of prey and as the percentage weight of the total quantity of prey consumed. Occurrence Weight Prey (%) (°o) Copepods: Calanoida 3.3 081 Calanus 8.9 9 55 Centropages 10.0 2 57 Pseudocalanus 17.8 6 28 Temora 17.8 8 06 Tortanus 17.8 6 27 Metndia 1.1 1 22 Cyclopoida Oithona 2.2 005 Unidentified 28.9 6 62 Copepod subtotal 37.8 41 43 Hyperiid amphipods 1.1 09 Mysids 1.1 32 Meganyctiphanes norvegica 1.1 041 Sagitta elegans 2.2 3991 Salpidae 1.1 04 Animal eggs 1.1 001 Trematodes 3.3 01 Animal remains 84.4 17 79 No stomachs exami ned 90 No stomachs empty or trace 32 Mean wt ot contents/stomach 15 3 mg Mean tish length 18 2 cm, SD = 1,8 for example, both Senta (1965) and Sekiguchi (1977) have shown that A. personatus is a plankton feeder relying heavily on copepods. In the North Sea, Roessingh' found that copepods were the major prey of A. marimis and occurred in roughly the same proportions in the stomachs as they did in the plankton. Macer (1966) examined the stomach contents of five species of sand lance from the North Sea. In all cases the sand lance were found to be plankton feeders, with copepods being the dominant prey for at least three of the five species. Only for A. lanceolatus was it conclu- sively shown that copepods were less significant as prey, being replaced by fish eggs, larvae, or small fish, particularly sm&W Am modytes. Two species oi sand lance are reported to occur along the Atlantic coast of North America, and only a small amount of information is available on their food habits. Richards (1963) examined the stomachs of 290 A. americanus in Long Island Sound; as for most other species of sand lance, copepods were the major prey. Centropages were preyed upon by 80% of the fish, Acartia by 55%, and Temora by 42%. Other prey included barnacle cyprids, fish eggs, dinoflagellates and diatoms, mysids, and sand lance larvae. Scott ( 1973) studied the food habits of 'Roessingh.M, 1957. Problems arising from the expansion of the industrial fishery for the sand Qe\. Ammodytes marinus Raitt, towards the Dutch coastal area. Near Northern Seas Committee, Int. Counc, Explor. Sea. 251 FISHERY BULLETIN: VOL. 77, NO. 1 A. dubiiis in the Canadian northwest Atlantic. Again, copepods, especially Calanus finmar- chicus, were the most important prey. Other prey included crustacean larvae, invertebrate eggs, polychaete larvae, larvaceans, fish eggs, pteropods, and barnacle cyprids. Comparison with plankton tows made at the time the fish were caught showed that A. dubttis had a definite pre- ference for the larger zooplankton such as copepods. From the data in Table 2, it is clear that the diet of A. americaniis from Stellwagen Bank is typical for this family of fishes. There are, how- ever, several small differences from other pub- lished results which are worth noting. For exam- ple, chaetognaths occurred rarely in the stomachs (2.2*^ ) but on a weight basis were only slightly less important than copepods. It would appear that chaetognaths are readily consumed if available. One notable exception to the list of prey is phyto- plankton. Both Richards (1963) and Scott (1973), as well asSenta ( 1965) and Macer ( 1965), reported finding diatoms or dinoflagellates in the guts of the fish they examined. In our study, no phyto- plankton was observed as part of the stomach con- tents. It is possible that at certain times of the year the occurrence of phytoplankton would be much more apparent in the guts, as might also be ex- pected for other prey such as crustacean larvae, barnacle cyprids. and larval polychaetes. SUMMARY 1. The meristic counts of sand lance reported are in agreement with published data and fall into the category of Ammodytes americaniis, the American sand lance. 2. Data on the relative abundance of sand lance from Northeast Fisheries Center spring and fall bottom trawl survey cruises indicate that there has been a substantial increase in sand lance abundance on Stellwagen Bank over the last 10 yr. This trend was also reflected by an increase in the numbers of sand lance larvae occurring in the spring ichthyoplankton results measured in the Gulf of Maine over the last 4 yr. This increasing trend in larval and adult sand lance abundance in the Gulf of Maine was typical of the northwest Atlantic from Cape Hatteras northward. 3. Sand lance encountered within the Province- town slope area ranged from 12 to 17 cm long (mean = 15 cm), and school strength numbered from about 100 to several thousand individuals. In contrast, individuals on Stellwagen Bank ranged from 7.4 to 24.0 cm FL (mean = 18.2 cm), while school strengths ranged from about 500 to tens of thousands of individuals. 4. School shapes were constant in appearance, vertically compressed, tightly compacted, and bluntly linear from a dorsal and ventral view. Provincetown slope schools were 1-5 m wide, 0.5- 1.5 m high, and 3-20 m long depending on school strengths. The nearest- neighbor distance between fish swimming in an undisturbed school was ap- proximately V2-% BL; between fish swimming in a school exhibiting a fright or avoidance reaction, 'a BL; and between fish swimming in a school en- gaged in feeding, approximately 1-1 '/2 BL. 5. The swimming motion of sand lance is sinusoidal in form and eellike in appearance. Schools swimming undisturbed and not engaged in feeding maintain an estimated swimming speed of 30-50 cm/s; during feeding they maintain an estimated speed of 15-25 cm/s; and during avoid- ance maneuvers, 70-120 cm/s. Feeding schools were observed in midwater and near the surface, but not on the bottom. 6. Sand lance were found to prefer clean sandy substrates conducive to burrowing. Sand lance usually disappear into the substrate in small groups, initially penetrating at an angle of 60°-75° from the horizontal, and continuing their sinuous movement until one-quarter of the body is buried. at which point the remaining three-quarters of the body is brought to a 20°-40° angle to allow the animal to settle into its resting position. Sand lance encountered on Stellwagen Bank were occa- sionally observed to partially emerge from the substrate headfirst and retract back into the bot- tom if approached. In contrast, sand lance along Provincetown slope would exit from the bottom when approached. Sand lance leaving the bottom exited at an angle of between 20° and 60° with an initial speed of 50-80 cm/s and built their speed up to 120 cm/s within the first 1.5 m from the bottom. Individual fish exiting would show schooling be- havior if another fish was exiting at the same time. 7. Copepods were the most important prey of A. americanus, occurring in 38'7f of the stomachs examined and making up 4Vi of the total weight of prey consumed. ACKNOWLEDGMENTS The authors gratefully acknowledge the assis- tance of the National Marine Fisheries Service, Woods Hole, Survey Unit for bottom trawl survey 252 MEYER ET AL ; AMERICAN SAND LANCE FROM THE GULF OF MAINE data; the laboratory scientific illustrator, Frank Bailey, for his many hours of patient craftsman- ship; and Rosalind Cohen and Nancy Kohler for their assistance with the stomach-content analysis. LITERATURE CITED Backus. R. h. 1957. The fishes of Labrador. Ammodytidae. Bull. Am. Mus, Nat. Hist. 113:307-308. BIGELOW, H. B., AND W. C. SCHROEDER. 1953 Fishes of the Gulf of Maine, U.S. Fish Wildl. Serv., Fish. Bull. 53. 577 p. BOWMAN. R. E., AND R. W. LANGTON. 1978, Fish predation on oil-contaminated prey from the region of the ARGO MERCHANT oil spill, //i In the wake of the ARGO MERCHANT, p, 137-141. Univ. R,I., Cent, Ocean Manage, Stud, CoviLL. R W, 1959- Food and feedmg habits of larvae and postlarvae of Ammodytes americanus, 1952-1955, In Oceanography of Long Island Sound, p, 125-146, Bull, Bingham Oceanogr, Collect,. Yale Univ, 17(1). GR.'\HAM, J, J, 1956, A mortality of sand launce, Ammodytes americanus. Copeia 1956:192-194, GROSSLEIN, M, D, 1969, Groundfish survey program of BCF Woods Hole, Commer, Fish Rev, 31(8-9):22-30. GROSSLEIN, M, D,, R, W, LANGTON, AND M. P. SiSSENWINE. In press. Recent fluctuations in pelagic fish stocks of the Northwest Atlantic. Georges Bank region, in relationship to species interactions. In Symposium on the Biological Basis of Pelagic Fish Stock Management No, 25, KUHLMANN. D, H. H,. AND H, KARST 1967, Freiwasserbeobachtungen zum Verhalten von To- biasfischschwarmen iAmmodytidae) in der westlichen Ostsee, Z, Tierpsychol, 24:282-297. (Also issued as Transl. Mar, Lab,. Aberdeen (1392).) LEIM. A. H,, AND W, B, SCOTT 1966, Fi.shes of the Atlantic coast of Canada. Fish. Res, Board Can,, Bull, 155, 485 p, Livingstone, R,, Jr 1962, Underwater television observations of haddock (Melanogrammus aegleftnus [Linnaeus]) in the cod- end. J. Cons. 27:43-48. MaCER, C. T, 1965, The distribution of larval sand eels (Ammodytidaei in the southern North Sea, J, Mar, Biol, Assoc, U,K, 45:187-207, 1966, Sand eels (Ammodytidae) in the south-western North Sea; their biology and fishery, Minist, Agric, Fish. Food (G.B.I Fish. Invest,, Ser. II, 24(6), 55 p. NORCRoss. J. J., w. H. ivl^ssmann. and E, B, Joseph 1961, Investigations of inner continental shelf waters off lower Chesapeake Bay. Part II Sand lance larvae. . 4m- modytes americanus. Chesapeake Sci, 2:49-59. PaDAN, J, W, (editori, 1977, New England Offshore Mining Environmental Study (Project NOMES), US, Dep, Commer,, NOAA Spec, Rep, NOAA ERL 1977, POPP Madsen, K, 1963, Tobis pa algediaet, Fiskeridir, Skr, .Ser, Teknol, Unders. 1963:46-47, REAY, R, J, 1970, Synopsis of biological data on North Atlantic sand eels of the genus A")"jo((v^cs..4 tobtanus, A. dubius.A. amencanus and.4 marinus. FAOFish, Synop, 82. 42 p. RICHARDS, S, W, 1959, Pelagic fish eggs and larvae of Long Island Sound. In Oceanography of Long Island Sound, p, 95- 124, Bull, Bingham Oceanogr, Collect, Yale Univ, 17(1). 1963, The demersal fish population of Long Island Sound, Bull, Bingham Oceanogr, Collect,, Yale Univ, 18(2), 101 p, 1965. Description of the post larvae of the sand lance (Ammodytes) from the east coast of North America, J, Fish. Res, Board Can, 22:1313-1317. 1976. Mixed species schooling of post larvaeof.4mmorfv(es he.xapterus and Clupea harengus harengus. J. Fish, Res. Board Can, 33:843-844, RICHARDS. S. W., AND A, W, KENDALL. jR 1973, Distribution of sand lance, Ammorfv(essp,.larvaeon the continental shelf from Cape Cod to Cape Hatteras from RV Dolphin surveys in 1966, Fish, Bull,. LI.S. 71:371-386. RICHARDS, S. W,, A. PERLMUTTER, AND D. C. McANENY 1963. A taxonomicstudyofthegenusAr?i/no(/y/es from the east coast of North America (Teleostei: Ammodytes). Copeia 1963:358-377. SCOTT. J, S, 1968, Morphometries, distribution, growth, and maturity of offshore sand launce (Ammodytes dubtus) on the Nova Scotia banks, J, Fish, Res, Board Can, 25:1775-1785, 1972, Morphological and meristic variation in northwest Atlantic sand lances (Ammodytes). J, Fish, Res. Board Can. 29:1673-1678, 1973, Food and inferred feeding behavior of northern sand lance (Ammodytes dubws). J, Fish, Res. Board Can 30:451-454. SEKIGUCHI. H. 1977, Further observation on the feeding habits of planktivorous fish sand-eel in Ise Bay, Bull, Jpn, Soc Sci, Fish, 43:417-422, SE.NTA, T, 1965, Nocturnal behavior of sand-eels, Ammodytes per- sonatus Girard. Bull. Jpn. Soc. Sci, Fish, 31:506-510. wahlert, G, v.. and h, V, Wahlert 1963. Beobachtungen an Fischschwarmen, VerofT, Inst, Meeresforsch , Bremerhaven 8:151-162, WILLIAMS, G, C, S, W, Richards, and E. G. Farnworth. 1964. Eggs of Ammodytes hexapterus from Long Island, New York. Copeia 1964:242-243, WINSLADE, P. 1974, Behavioural studies on the lesser sandeel. .4mmo- dytes marinus (Raitt), I, The effect of food availability on activity and the role of olfaction in food detection. II. The effect of light intensity on activity. III. The effect of tem- perature on activity and the environmental control of the annual cycle of activity, J, Fish. Biol. 6:565-599. WINTERS, G, H, 1970, Meristics and morphometries of sand lance in the Newfoundland area, J, Fish, Res, Board Can, 27:2104- 2108. 253 SEASONAL DISPERSAL AND HABITAT SELECTION OF GUNNER, TAUTOGOLABRUS ADSPERSUS, AND YOUNG TAUTOG, TAUTOGA ONITIS, IN FIRE ISLAND INLET, LONG ISLAND, NEW YORK' BoRi L. Olla, Allen J. Bejda, and A. Dale Martln^ ABSTRACT Results of field observations examining seasonal movements in the cunner, Tautogolabrus adspersus, and young tautog, Tautoga onitis, showed a small portion of a resident population located off Fire Island, N.Y., to disperse seasonally. Dispersal was from habitats which provide cover for both species throughout the year to seasonal habitats occupied primarily during summer. While both species exhibit a high degree of association with cover, results of experimental transfers of young tautog, monitored either ultrasonically or directly by divers with self contained underwater breathing apparatus, showed that fish will leave a suboptimal habitat even though cover is present. Dispersal and habitat selection are discussed in relation to seasonal changes in the environment and ecological requirements of the fish. Association with and dependence on cover by marine fishes have been observed for a wide vari- ety of species, exemplified by those which reside on coral reefs (e.g,, see: Hobson 1968, 1972, 1973; Sale 1969a, 1971, 1972, 1977: Smith and Tyler 1972, 1973). Although the number of species is much less, similar associations with cover also occur in temperate waters (e.g., see: Hobson 1971; Bray and Ebeling 1975; Hobson and Chess 1976; Olla et al. 1974, 1975). In both tropical (Hobson 1968, 1972) and tem- perate regions a major behavioral trait of the fam- ily Labridae is that members show a strong as- sociation with cover. Field studies on two temperate-water labrids of the northwest Atlan- tic, cunner, Tautogolabrus adspersus (Olla et al. 1975), and young tautog, Tautoga onitis (Olla et al. 1974), have demonstrated their close associa- tion with cover. Under laboratory conditions simi- lar associations have been observed for both species (cunner, Olla and Bejda unpubl. obs.; young tautog, Olla and Studholme 1975). Over several years, incidental sightings of cun- ner and young tautog always found them in as- sociation with cover. However, it was apparent that a substantial number offish were in areas in 'This work was supported, in part by a grant from the U.S. Department of Energy No. EX76-A-28-3045-A010. ^Northeast Fisheries Center Sandy Hook Laboratory, Na- tional Marine Fisheries Service, NOAA, Highlands, NJ 07732. Manu.script accepted October 1978. FISHERY BULLETIN: VOL. 77. NO. 1. 1979. which cover was present only seasonally, e.g., macroalgae and mussel beds. This suggested to us that there must be movement to these areas some- time after emergence from winter torpor (Olla et al. 1974, 1975) in March or April and movement away from these areas in the fall as the cover provided at these areas diminished. The possibil- ity of seasonal dispersal and habitat selection ap- peared likely. At least for adult tautog changes in habitat requirements with season have been es- tablished, as evidenced by the fact the fish migrate offshore to overwinter (Cooper 1966; Olla et al. 1974). In this study we have examined seasonal movements in cunner and young tautog, basing our observations on trapping and tagging, as well as surveying shelter sites seasonally by direct ob- servation with scuba or mask and snorkel. We also performed a series of transfer experiments to examine certain aspects of habitat selection. MATERIALS AND METHODS Based on previous scuba observations, six study sites (A, B, C, D, E, and F; Figure 1) within Fire Island Inlet, Long Island, N.Y., were selected at which to monitor the seasonal movements of cun- ner and young tautog. One site (A) was inhabited throughout the year and will be referred to as a perennial site. The five other sites (B, C, D, E, and F) were utilized only during late April through 255 FISHERY BULLETIN: VOL 77, NO 1 Figure l. — Location of study sites for cunner and young tautog within Fire Island Inlet, Long Island, N-Y. i see text for site descriptions!. FIRE ISLAND INLET (s) © ■'• 7 3° n' '"') ^■:^ -^^ ■I g^ ATI AN TIC OCEAN ROBERT MOSES BRIDGE FIRE ISLAND October and will be referred to as seasonal sites. A description of each site follows. Site A was the boat basin at the Fire Island Coast Guard Station, an open pentagon ( 110 ^ 52 X 47 m), constructed of tongue-and-groove planks, steel sheeting, and piles (011a et al. 1975). Along the outer perimeter was a zone of riprap (0.2- 0.4 m in diameter), 3 m wide and 2 m high. The mean water depth ranged from 2.4 to 8.8 m. Beds of the mussel, Mytilus edulis. were located along the walls, piles, and bottom. Site B was a 20.3-cm diameter drain pipe originating at the Fire Island water treatment plant. Located at a mean depth of 7.5 m, a 1.5-m section of the pipe was exposed and paralleled the bottom at a distance of 1 m. Beds of mussels sur- rounded the pipe in about a 6-m radius. Site C was one of the support piers for the Robert Moses Bridge, consisting of quarried stone and reinforced concrete. The mean water depth was 7.5 m. The pier was incrusted with mussels to a depth of 2 m below the high water mark. Sites D and E each consisted of an exposed verti- cal mud bank about 6 m long and 1 m high. Irregu- larly spaced along the face of each bank were ap- proximately 35 to 50 holes, apparently a result of erosion, varying in size from 12 to 20 cm wide and 5 to 15 cm deep. Small clumps of mussels were distributed along the top of each bank. Site D was at a mean depth of 6.0 m and Site E at 7.6 m. Site F was a grass bed which bordered a rocky shore line for 75 m and extended out from the shore 13-20 m. During the late spring and sum- mer, the area typically consisted of dense growths of eelgrass, Zostera marina, and algae iCodiurn spp., Enteromorpha spp., Polysiphonia spp., and Ulva spp.). Beds of mussels were interspersed be- tween the vegetation. Water depth throughout the area varied from 0.3 to 1.5 m. A seventh area, a small cove at the mouth of Fire Island Inlet, not designated in Figure 1, was the site of two transfer experiments involving ex- perimental cover. This site had a barren sand bot- tom, primarily dredge spoil, at a mean depth of 3.7 m. Three methods, trapping, direct visual counts, and tagging, were used to monitor, for both cunner and tautog, the periods and limits of movements as well as the types of habitats utilized. Fish traps were placed at Sites A, B, C, D, and E with two traps at Site A from March through November, one trap at Site B from May through November, and one trap each at Sites C, D, and E from June through November. Traps at each site were pulled at regular weekly intervals throughout the study and the number of cunner and tautog recorded. To compare the catch of the traps at the perennial site with the catch at the seasonal sites, we calculated the mean number offish caught per trap per week for each habitat type. Traps captured cunner rang- ing in size from 3.9 to 25.0 cm ix = 14.5 cm) and tautog from 7.3 to 35.0 cm l.v = 16.9 cm). Traps also provided the fish for the tagging portion of the study, as well as one means of recapture. Visual counts of cunner and tautog were made at Site F from the end of February through Oc- tober. A series of six transects the length of the site and 3 m wide were swum by divers, counting all 256 OLLA ET AL.: SEASONAL DISPERSAL OF CUNNER AND TAUTOC, tautog and cunner observed within each transect with the sum of the six transects being the total count. Cunner and tautog ( 314.0 cm) trapped at Sites A, B, C, D, and E were tagged throughout the study with Floy-67C^anchor tags. Tags were con- secutively numbered allowing identification of in- dividual fish and their release site. Each tag was printed with a request for fishermen catching tagged fish to return the tag, accompanied by in- formation as to the location and date the fish was caught. Fish were recaptured either in our traps or by recreational fishermen. Ultrasonic tracking was employed for short- term monitoring of movement and cover associa- tion of young tautog residing at both a perennial (Site A) and seasonal (Sites B and F) habitats. Four fish (two at Site A, one at Site B, and one at Site F) were individually tracked using the same procedures previously described by 011a et al. (1974, 1975) for capturing, handling, and track- ing. A series of transfer experiments was conducted to examine habitat selection in young tautog. All fish were captured at Site A and released at either existing, seasonal habitats (Sites B and C) or at experimental habitats which we established (see below). Fish were transferredby boat in 100-1 bar- rels of aerated seawater with the time to travel from capture to release sites ranging from 5 to 15 min. Four fish (three at Site B and one at Site C) were separately released at the seasonal habitats and tracked ultrasonically. Five transfers were made to the experimental habitats. One transfer was a single fish, released and monitored ultrason- ically. The other transfers consisted of four group releases with 10 fish/group. The response of the fish in these releases was monitored directly using scuba. While lying motionless, 5 m from the re- lease site, the observer recorded at 1-min intervals the number offish present. Cover abthe experi- mental habitats consisted of masonry structures constructed from standard cement blocks (20 x 20 X 40 cm) positioned in a manner which laterally exposed the central cavities (7 « 13 > 20 cm) ol each block. Cement blocks had been shown to be readily acceptable as cover by young tautog in the laboratory (OUa and Bejda unpubl. obs.). The structure for the single fish release was a four- block cube (40 X 40 x 40 cm). Two structures were used in the group releases. They were identical 12-block rectangular prisms ( 120 x 40 « 40 cm). RESULTS Catch and Direct Sightings at Seasonal and Perennial Habitats It was apparent from catch data and direct un derwater sightings that a majority of the habitat sites were utilized only seasonally by both cunner and young tautog. Throughout the summer, sub- stantial numbers of fish were captured at Sites A-E (Table 1) or sighted directly at Site F (Table 2). In September, there was a gradual decline in the catch of cunner and in October a sharp decline in both cunner and tautog at Sites B-E (Table 1). At Site F, direct visual counts indicated the same general trend (Table 2). However at Site A, while there was little change in catch during September, the catch of both species increased in October (Ta- ble 1). In November, Sites B-F were observed di- rectly with scuba and no fish were sighted. At Site Table 1. — Mean monthly catch of cunner and young tautog at perennial (A) and seasonal (B-E) sites. Mean catch/unit effort' Cunner Tautog Perennial Seasonal Perennial Seasons Month site sites site sites Marcii 11.0 ND^ 65 ND April 36.0 ND 27 tiJD May 6.8 9.5 25 92 June 19.7 8.5 1 3 106 July 13.8 5.3 06 11 9 August 218 61 62 98 September 21.9 2 8 86 80 October 34 3 149 10 November 97 38 'Unit eftorl = one trap fished 1 wk, -ND ^ no data Table 2.— Visual counts using scuba or mask and snorkel ot cunner and young tautog at seasonal Site F. ^Reference to trade names does not imply endorsement nt commercial products by the National Marine Fisheries Service, NOAA. Total number Total number Date Cunner Tautog Date Cunner Tautog Feb 28 July 2' 53 7 Mar 4 8^ 165 60 12 9= 93 27 20 10= 89 16 25 15 107 29 Apr 2 16' 42 13 29 17 3 29 44 24 May 20 29 11 Aug 12 63 20 22 74 20 13 169 71 29 60 15 Sept 3 42 7 June 5 65 14 24 34 6 11 79 19 Oct 2 18 10 20 26 69 12 29 'Mean ot two counts 'Mean of three counts 25; FISHERY BULLETIN: VOL, A, although large numbers of fish were sighted, the catch was declining (Table 1). The decline in catch at Site A may be related to lowered activity associated with decreasing temperature with the fish overwintering in torpor at this site (011a et al. 1974, 1975). Although traps were not in place in Sites B-E earlier than May, no fish were sighted directly in these areas or at Site F (Table 2 ) prior to mid- or late April. The presence offish at Site A throughout the year led us to term this a perennial habitat, while Sites B-F, where fish were only seen seasonally, we defined as seasonal habitats. Recaptures Tagged fish showed limited movements, with 91.3% of the cunner and 73. 2*;^ of the tautog recap- tures occurring at the same site at which they were released (Table 3). For the remainder of the fish, i.e., those recaptured at other sites, there were seasonal differences in where they were cap- tured. From May through August, recaptures were at seasonal as well as perennial sites (Table 3). But then from September through November, all recaptures were from sites which would be con- sidered perennial, including ones outside the study area (Table 3). Movements and Association with Cover of Young Tautog at Seasonal, Perennial, and Experimental Habitats In an earlier study, we had established that young tautog remained within several meters of cover (011a et al. 1974). Specifically, the cover re- ferred to in that study was Site A, identified in this study as a perennial habitat. To reconfirm the observation of the previous study, two fish ( no. 1,2; Table 4) were ultrasonically tracked for 48 h at Site A. Agreeing with the earlier results, both fish remained within several meters of the site. The question we next addressed was whether young tautog showed a similar association with cover at seasonal habitats. To answer this ques- tion, we captured and released two fish affixed with ultrasonic tags at Sites B (no. 4; Table 4) and F (no. 3; Table 4). The results of tracking showed the two fish to have a similar affinity to these sites as the fish had to the perennial one. remaining within 3 to 6 m of cover. The area over which the fish ranged varied with the size of the site. For example, when fish no. 3 was released at Site F, which consisted of beds of algae and eelgrass measuring about 15 75 m, it moved freely throughout the habitat, but never more than several meters beyond its perimeter. On the other hand, fish no. 4 released at Site B where cover was highly limited (0.2 x 1.5 m) ex- hibited less movement, while again remaining within several meters of cover. It appeared that the close association to cover was the same at both seasonal and perennial habitats. Thus far, all of the fish that were tracked had been released at the same site at which they were captured. Our next question was whether fish that were displaced from where they were captured T.'\BLE 4- — Size, capture and release sites i Figure 1 ». and period monitored for nine young tautog ultrasonically tracked. Tracking Number TL (cm) Capture site Release site duration (h) 1 22.5 A A 48 2 24 A A 48 3 20.2 F F 24 4 245 B B 48 5 21.5 A B 48 6 228 A B 72 7 23.0 A B 48 8 24.0 A C 48 9 22 5 A (') 24 'Experimental cover Table 3. -Nuinber and location of recaptures of cunner and young tautog tagged and released at perennial and seasonal sites. Release No Total no No recaptured No recaptured al otlner sites f^lay-August September Perennial ■November Perennial Seasonal Seasonal Species site released recaptured at 1 elease site sites sites sites sites Cunner A 875 176 166 5 1 4 B 83 13 7 3 3 C 15 D 54 6 5 1 E 10 Total 1.037 195 178 5 4 8 Tautog A 245 25 20 1 4 B 283 29 18 5 6 C 72 12 11 1 D 123 3 2 1 E 41 2 1 1 Total 764 71 52 7 12 C 258 OLLA ET AI. SEASONAI, DISPERSAL. OF IlINNER AND TAUTOC would accept and remain at a different site. Four fish captured at Site A, the perennial habitat, were affi,xed with ultrasonic tags and released at either of two seasonal sites. Three fish were released separately at Site B (no. 5-7; Table 4) and a fourth at Site C (no. 8; Table 4) and individually tracked for 48 to 72 h. The fish appeared to accept the transfer to a different habitat with all four fish remaining within several meters of the release site. The close association with cover exhibited by fish ultrasonically monitored at both perennial and seasonal habitats indicated the possibility that the apparent dependence on cover might be such that a fish would remain at any object that afforded cover. To examine whether the presence of cover was the sole determinant of habitat accep- tance, we transferred a fish from Site A to a struc- ture constructed of cement blocks, measuring 40 - 40 X 40 cm, and located on a sand bottom 50 m from a habitat with which fish were associated (Site F). The fish (no. 9; Table 4), during the first 5 min after release, circled the structure and moved farther away with each circuit, showing little, if any, attraction. When about 10 m from the struc- ture, it swam shoreward and reached Site F about 5 min later. The fish remained at this site during the next 24 h, showing the same degree of move- ment exhibited by fish no. 3 (Table 4) which had been previously captured and released at this site. It was possible that the fish moved from the structure because of its proximity to a natural habitat, therefore affording it a choice. It was also possible that social factors related to the release of a single fish rather than a group may have played a role in the rejection of the structure as a habitat. To control for these factors, we next released fish in a group of 10, 4.5 km from their home range and 100 m from the nearest natural habitat at which conspecifics were present. To broaden the scope of our queries we included the possible influence of factors such as food and naturally occurring cover on habitat selection. Two cement block structures ( 120 ' 40 > 40 cm) were placed 10 m apart. Both were identical except that while one consisted simply of bare cement blocks, the other contained clumps of mussels and algae iUlva sp.), naturally occurring food and shelter material. Two groups of 10 fish each (15-23 cm) captured at Site A, were released together at each habitat while being ob- served with scuba. Within 5 min of being released, the fish left both structures, swimming away in various directions. The habitats were then modified by the addition to each of a fish trap. To the habitat which con- tained mussels and algae the trap added was over- grown with various fouling organisms and had been in continuous use over a period of 4 to 5 mo, capturing both tautog and cunner. The fact that this trap captured fish consistently led us to con- clude that it provided an attractive stimulus or set of stimuli. The trap added to the bare structure was new. A group of 10 fish ( 10-25 cm), captured at Site A, was released at each habitat. As previ- ously, the fish left the bare habitat within 5 min. Dispersal from the other habitat was more gradual with the last fish leaving about 60 min after release. In all instances, the fish departed, indicating that factors in addition to those pro- vided were necessary for mediating habitat selec- tion. DISCUSSION It was clear from the results of trapping, tag- ging, and direct underwater observation that some portion of the cunner and young tautog popu- lations dispersed in late spring. The dispersal was from the boat basin (Site A, which we termed a perennial habitat) to habitats that were utilized only seasonally. Once adopting a seasonal habitat, the fish appeared to remain there until fall. Then there was a general movement back to a perennial habitat, but as was evident from the capture of tagged fish at perennial sites outside of the study area, not necessarily the one from which they dis- persed in the spring. Once arriving at a perennial habitat, the fish remained to overwinter in torpor, not emerging until sometime in early spring when the temperature reached 5° to 6°C (011a et al. 1974, 1975). Supporting our findings for seasonal movement, Briggs (1977) found a marked increase in the number of young tautog captured during the fall at the Kismet artificial reef, 6 km from our study area. This increase, we surmise, also reflects the movement of fish from seasonal habitats to one which appears to be perennial. In attempting to define habitat requirements for both species, it is apparent that cover is a critical factor. During the day when these fish are active, they remain within several meters of cover, and at night when quiescent and unresponsive, they are either in, against, or under cover (Olla et al. 1974, 1975). Once becoming torpid in winter, they re- main under cover until spring. It seems reason- 259 FISHERY BULLETIN; VOL. 77, NO. 1 able to assume that dependence on cover is related to protection from predation. Large adult tautog, not as vulnerable to predation because of their size, move away sometimes considerable distances from cover each day to feed (011a et al. 1974). With such a strong tendency to remain in prox- imity to cover, the question arises as to what causes a portion of the population to disperse. It is clear that environmental factors are changing with season as are the requirements of the fish. Both species in the spring have emerged from 3 to 4 mo of torpor, which has required them to live on stored energy reserves. The need for food arising from winter deprivation, coupled with the in- creased metabolic requirements resulting from the increase of temperature in late spring, might stimulate feeding and the competition for food. At least until June, the major dietary component for both species is Mytiltis cdulis 1 011a et al. 1975), and thus competition for food would be both intra- and interspecific. The spawning season for cunner also peaks dur- ing June (Dew 1976). Thus we can e.xpect that competition for participation in either group spawning (Wicklund 1970) or pair spawning (Pot- tle and Green'*) would increase. This increase would relate either to participation in gamete re- lease or male territoriality as related to pair spawning. Although the majority of tautog studied were immature and would generally not be involved in the reproductive competition, it is possible that the arrival from offshore of adults that are in spawning condition (011a et al. 1974) and which we know to be highly aggressive (011a and Samet 1977; 011a et al. 1977) may also play a role in the dispersal of the smaller fish. Competition in both species is manifested through aggression (for tautog, OUa and Studholme 1975; 011a et al. 1977, 1978; for cunner, 011a and Bejda unpubl. field and laboratory obs.). The increase in aggression that may occur at the perennial habitat as a result of competition could cause this site to become suboptimal, at least for some portion of the population. Seasonal changes in levels of aggression within a population might result in corresponding seasonal changes in the carrying capacity of the habitat. "Pottle.R. A.,andJ. M.Green. 1978. Field observation.s on the reproductive behaviour of the cunner, Tautogulahrux adspersus (Walbaumi. in Newfoundland. Unpubl. manuscr., 27 p. Department of Biology and Marine Science.s Research Laboratory, Memorial University of Newfoundland, St. John's, Newfoundland A13 3X9. 260 Support for the idea that fish will leave a subop- timal habitat is reflected in the results of the transfer experiments where young tautog left the cement block structures provided for them. Simi- lar results were obtained with juvenile cunner (Olla unpubl. obs.). In attempting to examine the mechanism for habitat selection in the manini, Acanthurus triostegus sandvicensis , Sale (1969b) performed a series of laboratory experiments and concluded from these that there was a higher in- tensity of exploratory behavior exhibited when animals were subjected to an inadequate envi- ronment. Similarly, it could be concluded that young tautog were showing greater exploratory behavior when they left the experimental cover provided for them. A portion of the fish that dis- perse will be lost, with the probability of survival decreasing as the amount of time taken to find a suitable habitat increases. Nevertheless, through this mechanism, fish are able to utilize seasonally available resources. The return to perennial habitats from seasonal ones in the fall may also be related to these becom- ing suboptimal for the fish, but for different reasons than those which caused dispersal in the spring. At habitats which exist only seasonally, as in the case with macroalgae and eelgrass beds, the actual cover that these beds provide begins to wane as they start to die back in the fall. Although some sites were structurally more permanent, such as Site B (the submerged pipe), the animals did not use them as perennial habitats, and the changes which were occurring to render them sub- optimal were not obvious. Besides changes in the environment, of prime importance for considera- tion is the change in the animals' requirements for cover. What served adequately in summer is not adequate for winter. In observing cunner and young tautog in the field during winter torpor, both species were found in deep recesses and often buried under several millimeters of sand, farther under cover than ob- served during nighttime quiescence in summer. This afforded them greater protection during the winter. The seasonal sites studied did not provide cover equivalent to that at perennial ones, which have numerous deep crevices and holes. Laboratory studies on adult tautog confirm the change in cover requirements during winter tor- por (Olla etal. 1977; 01 la and Studholme 19781. As temperature declined, the fish began to show an affinity for those structures which would serve as cover during the winter at least 1 to 2 wk before OLLA ET AL SEASONAL DISPERSAL OF CUNNER AND TAUTOG torpor was observed at which time the fish actu- ally burrowed under them being almost com- pletely covered by sand. These structures differed from the ones the fish used throughout the rest of the year at night. In the field, the offshore move- ment of the adults begins 4 to 8 wk before they would encounter temperatures that would induce torpor (011a et al. 1974), indicating a change in habitat requirements with season. About the same time that adult tautog are moving offshore, cunner and young tautog are moving to perennial sites. Association with cover is no doubt a strongly motivated behavior for young tautog and cunner, but one for which there is a considerable range of adaptation. Under seasonally changing conditions or when habitats are simply suboptimal as in the transfer experiments, the animals will disperse, leaving cover at the risk of predation until alter- nate sites are found (as discussed earlier). On the other hand, a closer association results from tran- sient environmental causes, such as the presence of predators resulting in young tautog fleeing to cover (011a et al. 1974). Similarly, elevated tem- perature stress causes young tautog to associate more closely with cover, at least under laboratory conditions (011a and Studholme 1975). ACKNOWLEDGMENTS We wish to thank the personnel of the U.S. Coast Guard, Fire Island Station, N.Y., for their assistance and cooperation. LITERATURE CITED BRAY. R. N., AND A, W. EBELINC. 1975. Food, activity, and habitat of three "picker-type" microcamivorous fishes in the kelp forests off Santa Bar- bara, California. Fish. Bull., U.S. 73:815-829. BRIGGS. P. T. 1977. Status of tautog populations at artifitial reefs in New York waters and effect of fishing. N, Y. Fish Game J. 24:154-167. Cooper. R. a. 1966. Migration and population estimation of the tautog. Tautoga onitts (Linnaeus), from Rhode Island. Trans. Am. Fish. Soc. 95:239-247. DEW, C. B. 1976. A contribution to the life history of the cunner, Tautogolabrus adspersus. in Fishers Island Sound, Con- necticut. Chesapeake Sci. 17:101-113. HOBSON. E. S. 1968. Predatory behavior of some shore fishes in the Gulf of California. U.S. Fish Wildl. Serv., Res. Rep. 73. 92 p. 1971. Cleaning symbiosis among California inshore fishes. Fish. Bull., U.S. 69:491-523. 1972. Activity of Hawaiian reef fishes during the evening and morning transitions between daylight and darkness. Fish. Bull., U.S. 70:715-740. 1973. Diel feeding migrations in tropical reef fishes. Hei- gol. wiss. Meeresunters. 24:361-370. HOBSON. E. S., AND J. R. Chess 1976. Trophic interactions among fishes and zooplankters near shore at Santa Catalina Island, California. Fish. Bull., U.S. 74:567-598. OLLA. B. L., A. J. BEJDA. AND A. D. MARTIN 1974. Daily activity, movements, feeding, and seasonal occurrence in the tautog, Tautoga onitis. Fish. Bull., U.S. 72:27-35. 1975. Activity, movements, and feeding behavior of the cimner, Tautogolabrus adspersus. and comparison of food habits with young tautog, Tautoga onitis. off Long Island, New York. Fish. Bull., U.S. 73:895-900. OLLA. B. l., and C. Samet 1977. Courtship and spawning behavior of the tautog, Tautoga onitis (Pisces: Labridae). under laboratory condi- tions. Fish. Bull., U.S. 75:585-599. Olla. B. L., C. Samet. A. J. Bejda, and A. L. Studholme. 1977, Social behavior as related to environmental factors in the tautog, roii/o^a oni/is. In Thebehavior of marine organisms: plenary papers, p. 47-99. Mar. Sci, Res. Lab. Tech, Rep, 20, Memorial Univ. Newfoundland. Olla, B. L., and a, L, Studholme 1975, The effect of temperature on the behavior of young tautog. Tautoga onitis (L,), In H, Barnes (editor!. Pro- ceedings of the ninth European marine biology sym- posium, p, 75-93. Aberdeen Univ. Press. 1978. Comparative aspects of the activity rhythms of tautog, Taw^oga onitis . bluefish, Pnmatomus saltatrix . and Atlantic mackerel. Scomber scombrus, as related to their life habits. In J, E, Thorpe (editor). Rhythmic activity of fishes, p. 131-151. Academic Press, Lond. Olla, B. L., a, L, Studholme, a, J, Bejda, C. Samet, and A, D. Martin, 1978, Effect of temperature on activity and social behavior of the adult tautogTautoga onitis under laboratory condi- tions. Mar, Biol. (Berl.i 45:369-378. Sale, P. F, 1969a, Pertinent stimuli for habitat selection by the juvenile manini, Acanthurus triostegus sandvicen- sis. Ecology .50:616-623. 1969b. A suggested mechanism for habitat selection by the juvenile manini Acanthurus triostegus sandvicensis Streets. Behaviour 35:27-44. 1971. Extremely limited home range in a coral reef fish, Dascyllus aruanus (Pisces; Pomacentridae), Copeia 1971:324-327, 1972. Influence of corals in the dispersion of the pomacen- trid fish, Dascyllus aruanus. Ecology 53:741-744. 1977. Maintenance of high diversity in coral reef fish communities. Am, Nat, 111:337-359, Smith, C, L,, and J, C, Tyler 1972, Space resource sharing in a coral reef fish communi- ty. In B, B, CoUette and S, A, Earle (editors). Results of the tektite program: Ecology of coral reef fishes, p, 125- 170, Nat, Hist, Mus, Los Ang, Cty,, Sci, Bull, 14. 1973 . Direct observations of resource sharing in coral reef fish. Helgol, wiss. Meeresunters, 24:264-275, WICKLUND, R. I. 1970. Observations on the spawning of the cunner in wa- ters of northern New Jersey. Chesapeake Sci. 11:137. 261 BIOLOGY OF WALLEYE POLLOCK, THERAGA CHALCOGRAMMA, IN THE WESTERN GULF OF ALASKA, 1973-75 Steven E. Hughes and George Hirschhorn' ABSTRACT Data on the stock composition, growth, mortality, and abundance of walleye or Alaska pollock, Theragra chakogramma , in the western Gulf of Alaska were collected during six demersal trawl surveys in 1973-75. Over 102,000 km^ of continental shelf and slope were surveyed; most of this area was covered during spring and summer. Using the area-swept technique and catchability coefficients of 1.0 and 0.5, the e.\pIoitable pollock biomass in the survey region was between 610,000 and 1,220,000 metric tons. The percentage of larger and older fish increased to the west. Sexual maturity was reached at age 3, Growth completion rates ranged from 0.2 to 0.4. Natural mortality was estimated (assuming natural mortality equals growth completion ratei at 0.33 for males and 0.30 for females. Variations in growth completion rates within year class and variable recruitment strength indicated a probable east-west separation of pollock spawning populations near Kodiak. The National Marine Fisheries Service conducted six trawl surveys of walleye or Alaska pollock, Theragra chalcogramma , and other groundfish re- sources in the western Gulf of Alaska from Cape Cleare, Montague Island, west to Unalaska Island during each spring and summer of 1973-75 (Fig- ure 1). These surveys have provided information on the geographic and bathymetric distribution and densities of species within the groundfish commmunity (Hughes and Parks 1975). An additional goal of these surveys and subject of this report was the collection of pollock life his- tory data for management purposes. METHODS Six cruises were completed. Five were con- ducted from the 28-m NOAA RV John N. Cobb, employing 400-mesh Eastern otter trawls with 30-m footropes. During these five surveys, fishing was conducted following a predetermined, strat- ified random survey pattern (Grosslein^l. Fishing densities varied from one 30-min trawl/1,370 km'-^ in strata of anticipated low densities (depths of 90 m or less) to one 30-min trawl/515 km^ in the remaining depth strata of 91-180 m, 181-270 m. 'Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake Boulevard East, Seat- tle. WA 98112. ^Grosslein, M. D. 1969. Some observations on accuracy of abundance indices derived from research vessel surveys. Un- publ. manuscr. Northeast Fisheries Center, National Marine Fisheries Service, NOAA, Woods Hole. MA 02543. Manuscnpt accepted August 1978 FISHERY BULLETIN; VOL. 77, NO. 1, 1979 271-360 m, and 361-450 m. The other cruise was conducted from the 26-m chartered trawler A«/!a Marie, with similar but larger modified Eastern and Norwegian-style otter trawls with about 34-m footropes. Because the purpose of the Anna Marie survey was to determine commercial production potentials (Hughes and Parks 1975), fishing was concentrated where fish schools were detected by echo sounding; no predetermined survey pattern was followed. Consequently, the A;!na Mane data (Sanak-Unalaska. May-June 1974) were not used for pollock density or biomass studies. Stretch mesh measurements ( 1 knot included ) of all trawls ranged from 10.2- to 14.0-cm mesh in the intermediate and cod end sections. Trawls mea- sured by scuba divers at depths of 15 m indicated vertical heights of 2-3 m and horizontal spread of 11-13 m. Methods of selecting random samples of pollock for collection of biological data were consistent during all surveys (Hughes 1976a). Length- frequency fork length (FL) measurements to the nearest centimeter by sex were randomly collected from each catch with the desired sample size being 300 pollock. While processing pollock for length- frequency data, stratified subsamples of otoliths ( 10/sex per cm) and individual fish weights (5/sex per cm) were taken ( ±5 g). Otoliths were stored in ethanol in plastic boxes (Hughes 1976b) and ages were later determined as described by LaLanne (in press). Length-frequency distributions determined 263 FISHERY BULLETIN VOL 77, NO 1 Figure l.— Western Gulf of Alaska regions where trawl surveys were completed, 1973-75. from the five standard resource assessment sur- veys were weighted by catch magnitude and area within sampling strata, whereas data collected during the commercial fishing (Sanak-Unalaska, May-June 1974) trials were weighted only by catch magnitudes. Length-age data from the strat- ified otolith collections of sexed pollock in each survey region (Figure 1) were compiled into age- length keys. The proportions of observed ages on each length interval above 19 cm were applied to the weighted length frequencies. For this we used a computer program by Allen (1966! modified to exclude ex- trapolations beyond the aged length range and to include the calculation of mean length at age, as well as numbers at age. Thus numbers and size of pollock in the fishable population were estimated by region, age, and sex. Resulting analysis provided weighted age com- position data and mean length-at-age data for growth studies. Von Bertalanffy growth-in-length parameters and length-weight data were deter- mined for each region. An area-swept technique ( Al verson and Pereyra 1969) was employed to estimate the pollock exploitable biomass, using the relation Pw = (CPUE) ( A)/(f ) (a) where Pu' is equal to the aver- age standing stock, in weight, of the catchable population. A is the total area; a is the average bottom area covered by the trawl per standard tow; and c is a coefficient related to the effective- ness of the trawl in capturing pollock. Whereas earlier studies of Alaskan pollock as- sumed c = 1.0 (Alverson and Pereyra 1969), pol- lock were often acoustically detected ofT the sea bottom and above the trawl's headrope. Estimates ofc given for some gadoid species of the northeast- ern Atlantic Ocean indicated c may not exceed 0.51 (Edwards 1968). In this report, values of both 0.5 and 1.0 provide a conservative range of biomass estimates. RESULTS The surveys resulted m 144 fishing days on the grounds and 368 successful trawl hauls. Over 455,000 kg of groundfish were sampled, including 49,912 pollock which were processed for biological data. Size and Age Composition In the three regions where spring and summer surveys were conducted during the same year (Shelikof Strait 197.3; southeast Kodiak 1973; and Sanak-Unalaska 1974), seasonal variations in size and age composition were attributed to fish measuring <28 cm which represented the 1- and 2-yr-old juvenile segment of the population (Fig- ures 2, 3). However, substantial differences be- tween regions indicate that size and age of adult pollock consistently increased when moving from the southeast Kodiak and Shelikof Strait regions westward through the Chirikof region and into the Sanak-Unalaska region. The age composition data also indicated that Gulf of Alaska pollock display strong variations in year-class strength. Both 1967 and 1970 year class- es showed unusually strong recruitment. Indica- tion of a strong 1967 year class, sampled as 6-yr- olds, was noted during the May-June 1973 surveys of the southeast Kodiak and Shelikof regions. The relative strength of this year class was again noted 3 mo later during the August-September survey of southeast Kodiak and. particularly, of Shelikof Strait. Farther west, in the October 1973 Chirikof 264 HIUJHES and HIRSCHHORN BIOLOGY OF WAI.LEVE POLLOCK (%) ASNinoatid (%) ADN3no3aj (%) ADNsnoaad 265 FISHERY BULLETIN: VOL. 77. NO, 1 S E KOCIAK REGION MAY -JUNE 1973 TEMALES N. l273 = 1967 YEAR CLASS !l^' 1970 YEAR CLASS SHELIKOF SIRAIT REGION auG - SEPT 1973 EMflLE N : Sn Figure 3.— Weighted agt^frequency distributions of male and female walleye pollock by survey region and season in the western Gulf of Alaska. 1973-75. 266 HUGHES and HIRSCHHORN BIOLOGY OF WALLEYE POLLOCK survey, 6-yr-old pollock were dominant. One year later, in the most westward region (Sanak- Unalaska 1974), the prominence of the 1967 year class as 7-vr-olds was apparent during both the May-June and July-August surveys. During the May-June and August-September 1973 surveys of southeast Kodiak and Shelikof Strait, S-yr-old pollock ( 1970 year class) were dom- inant. The unusual strength of this year class was again noted 2 yr later east of Kodiak as 5-yr-olds during the 1975 Kenai survey. However, recruit- ment of the 1970 year class was not successful west of Kodiak, as shown by the low relative abundance of 3-yr-olds in the Chirikof region in 1973, of 4-yr- olds in the Sanak-Unalaska region in 1974, and of 5-yr-olds in the Chirikof region in 1975. Maturity and Sex Composition Most adult pollock ( >859c ) had spawned prior to our earliest sampling (May). Based upon a subjec- tive evaluation of gonad condition from pollock collected during May, it appeared that prime spawning periods were March and April. Ripe males and females were obtained as late as Au- gust, but these represented <0.1% of samples. Both sexes were fully recruited to the spawning population at age 3. Mature or recently spent age 2 males were encountered but represented <59e of that age-group. Mature or spent age 2 females were not encountered; however, minor gonad en- largement was noted. Means of lengths at first maturity in spring surveys were 29-32 cm for males and 30-35 cm for females. Our data indicate that sex composition fluc- tuates around 50'+^ at 20-45 cm FL but that females become progressively more dominant with larger size ( Figure 4 ). As will be shown later, the point of major difference in sex ratio (45 cm) is composed primarily of age 4, 5 females and age 5, 6 males. Length-Weight Pollock length-weight data by sex were col- lected during the May-June and August- September surveys of the southeast Kodiak and Shelikof Strait regions in 1973. Data were also collected during the September-October 1973 sur- vey of the Chirikof region. Length-weight rela- tions were determined for these survey regions and periods (Figure 5) by fitting the logarithmic form of the equation (W = aL''). where W is body weight in grams and L is fork length in centi- meters, to the mean weight per centimeter-length interval. Comparison of these curves indicates that female pollock measuring >33 cm weighed con- siderably less than males of equal length during the May-June postspawning survey. Female weight gain during summer was more rapid than in males, and differences in weight-at-length in the Shelikof Strait, southeast Kodiak, and Chirikof regions were negligible during the August-October sampling. Regional differences during spring-summer periods were also noted. Shelikof Strait pollock were heavier than southeast Kodiak pollock of equal length during spring and considerably lighter during summer. This difference may be due to a more rapid weight gain in the southeast Kodiak region or to migration of the most healthy fish out of Shelikof. An additional factor suggest- ing migration was that samples of male pollock in Shelikof actually showed a weight loss from spring to summer. Density Distribution and Estimates of Standing Stock Pollock were distributed over depth intervals of 50-360 m (Table 1). Highest densities occurred at depths of 91-270 m during spring and summer. Geographically, densities were highest at Sanak-Unalaska (181-270 m), followed by south- east Kodiak (91-180 m). Spring-summer 1973 as- sessment surveys of Shelikof Strait and southeast Kodiak indicated highest densities during sum- mer. The summer biomass of pollock exceeding 20 cm FL was estimated as 610.000-1,200,000 metric tons (t) of whole fish (Table 1). Regional biomass estimates were greatest in the Chirikof region, followed by Sanak-Unalaska, southeast Kodiak, Kenai, and Shelikof Strait. Growth Length-age data from the nine surveys were fitted by the von Bertalanffy relation /, = L^ {l - exp k(t-tf^)} following computational procedures by Fabens ( 1965). Because variation in age range affects comparability of parameters (Hirschhorn 1974), curve fits over original age ranges were supplemented: 1) with fits over a standardized age range of 2-8 yr, 2 ) with an artificial data point ( 0,0 ) 267 FISHERY BULL? TIN VOl, 77 o < is < s o V ?- in o to O m CD ~ LjJ oc o o o o E o X 1- cc o uj S cr - o o — 1- o o o UJ cc If) o X ^ X 1- C-5 n ^ z LJ _l o Y tr o o o o o o o o o o O CO ID LJ cr < ^ _,'' V <^ y 1 1 iN33H3d iN30y3d lN33a3d o c 268 HUGHES and HIRSCHHORN BIOLOGY OF WALLEYE POLLOCK 2000-1 SHELIKOF STRAIT REGION MALE MAY -JUNE 1973 CT 1500 ^ 1000 >- o o oj 500- W=2 3775»I0'l""' -I 1 1 1 1 1 1 1 8 16 24 32 40 48 56 64 SE KODIAK REGION MALE MAY- JUNE 1973 W= 3.9344 X lo'' l' '*'° ./ X -T 1 1 r — -I 1 ; 1 8 16 24 32 40 48 56 64 SHELIKOF STRAIT REGION MALE AUG -SEPT 1973 W= 3 0410 X lO'' l'"" / -1 1 1 1 1 1 1 8 16 24 32 40 48 56 2000-1 1500 * 1000- 500 SE KODIAK REGION MALE AUG -SEPT 1973 W=98I78 K IQ-' L^^"^ / X -| 1 1 1 1 1 1 1 8 16 24 32 40 48 56 64 CHIRIKOF REGION MALE SEPT.- OCT 1973 W= 20188 X I0'2 L2754I n 1 1 1 1 1 1 1 8 16 24 32 40 48 56 64 2000 -1 SHELIKOF STRAIT REGION FEMALE MAY -JUNE 1973 "S. 1500- W= 5.6136 X 10'^ l3 0627 H I CD ^ 1000- .y >- Q 2 500- ^■' n ' 1 r-' T I 1 1 1 1 SE KODIAK REGION FEMALE MAY -JUNE 1973 W = 8 2943 X 10'' L ■3 I 2 9474 ■■/■ —\ 1 1 1 1 1 1 16 24 32 40 48 56 64 SHELIKOF STRAIT REGION FEMALE AUG -SEPT 1973 W= 4 4233 X 10'' l"'^' y / ■/. —I 1 1 1 1 1 r 8 16 24 32 40 48 56 FORK LENGTH (cm) 2000-1 S E KODIAK REGION FEMALE AUG -SEPT 1973 1500- W= 1.0769 X 10'^ |_2-9252 ; 1000- / 500- / y ' — 1 — 1 — 1 — 1 — 1 — 1 — 1 — 1 16 24 32 40 48 56 64 FORK LENGTH (Cm) CHIRIKOF REGION FEMALE SEPT -OCT 1973 W= 2829 X 10'^ L2.6667 Figure 5.— Length-weight rela- tionships of male and female wall- eye pollock by survey region and season in the western Gulf of Alaska. 1973-75. 16 24 32 40 48 56 64 FORK LENGTH (cm) 269 FISHERY BULLETIN: VOL, 77, NO 1 Table l. — Summary of exploitable walleye pollock biomass and density by depth strata and survey regions in the western Gulf of Alaska. Catchability coefficients 1.0 and 0,5 are used to produce a range of pollock biomass and density. Biomass estimates were calculated from the summer survey period due to limited spring survey coverage. Survey region and period Depth strata (m) Area surveyed (km^) Density (t/km') c = 1 c = 5 Exploitable b c = 1,0 iiomass (t) c = 0,5 Summer Kenai Peninsula (148 -152 W) July-Aug 1975 91-180 181-270 271-360 19.183 8.026 796 4 1 28 02 82 56 04 77.742 22.230 186 155,486 44,460 371 Regional total 28,005 100.158 200,316 SE Kodiak (152 -154'W) Aug-Sep 1973 55-90 91-180 181-270 271-360 7,302 6,143 1.475 737 22 16 1 99 4 4 32 2 19,8 16,180 99,042 14.706 32,360 198,085 29,412 Regional total 15,657 129.928 259,857 Shelikol Strait (Aug-Sep 1973) 55-90 91-180 181-270 381 3,341 2,713 02 58 10 04 11 6 20 89 19,480 2,610 178 38,960 5,221 Regional total 6,435 22,179 44.359 Chinkol (154 -159 W) July 1975 Regional total 55-90 91-180 181-270 9.439 12,749 11.661 33.849 10 136 02 20 27 2 04 9,082 173,583 11,220 193,885 18,163 347.168 22.440 387,771 Sanak-Unalaska (162-168 W) July-Aug 1974 50-90 91-180 181-270 271-360 361-450 6,647 8,935 912 703 322 27 13 1 31 8 54 26 2 63 6 18,060 117,096 29,107 36,120 234.192 58.214 Regional total 17,519 164,263 328.526 Survey total Spring SE Kodiak (148-152 W) May-June 1973 50-90 91-180 181-270 101,465 4,778 4.496 737 04 20 04 0.8 4,0 08 610.413 1.220.826 Regional total 10,011 Shelikof Strait (May- June 1973) 50-90 91-180 181-270 271-360 381 3.982 11.558 1.008 02 07 06 03 04 1 4 1 2 06 - - Regional total Sun/ey total 16.929 26,940 added on the assumption that at age length is near (Alverson and Carney 1975), and 3) with nominal ages or ring counts incremented by the fraction of a year between middates of spawning and sampling (A? in Table 2). Because each growth pattern in Figure 6 repre- sents a synthetic cohort, i.e., a composite of year classes, the departures from the pattern, gener- ated by members of the 1967 and 1970 year class- es, were examined in detail. According to the age composition discussed earlier, both year classes were encountered in relatively high abundance at one extreme of the survey range (Figure 3) and in low abundance at the other (the 1967 year class was prominent at Sanak-Unalaska, the 1970 year class at Kenai). To examine the evidence for a growth-density relation, the size differences be- tween the synthetic growth curves and observed mean lengths of the sampled age-groups of these year classes were calculated (lower part of Table 2). The results are shown along a schematic east- west axis in Figure 7. In the easternmost region ( Kenai), the strong 1970 year class indicates nega- tive departures from expectation (at age 5), whereas corresponding departures are positive for the relatively weak year class of 1967 (at age 8). In the westernmost region, the relative strengths of these year classes seemed to be reversed, and the direction of departures of their mean lengths at ages 4 and 7 also reversed. By this criterion, the segregation of the two components of each year class was most pronounced at the extremes and least SO in the intermediate Kodiak-Shelikof re- gion where the lines cross. Age-specific observed lengths of the 1970 and 1967 year classes were also compared directly with those of others, apparently weaker year class- 270 HUGHES and HIRSCHHORN: BIOLOGY OF WALLEYE POLLOCK Table 2.— Mean length (centimeters) at age of western Gulf of Alaska Theraga chalcogramma by survey and sex; growth parameters (L^, A', <„) for original and "selected" data sets, with standard deviation (a-) of departures from fit; departures of 1967 and 1970 year class mean lengths at age, from fit (A67YC, A70YC). Sanak Ctlirikol Kodiak May-June 74 Juiy-Aug 74 July 1975 Sept -Oct 73 May-June 73 Aug -Sept 73 M F M F 1^ F M F M F M h Item (0 17)' (0 42) (0,251 (050) (0 17) (0 42) Years of 1 _ 20.00 _ _ 1949 20 02 — — 23 07 23 09 age (0 2 25 52 24 36 29.55 29 75 24 70 24 99 27 15 27 99 25 24 2621 29 51 29 50 3 35 19 35 20 38 51 36 04 31 54 32 18 3501 3574 30 24 30 38 33 44 3385 4 39 59 40 17 41 16 42 14 33 88 34 98 39 32 40 58 3877 38 44 40 37 41 48 5 43 68 44 63 44 07 45 18 38 41 40 07 40 18 4263 40 30 43 55 41 70 44 32 6 45 16 46 81 45 01 47 05 42 10 43 05 41 36 43 82 43 26 45 15 43 37 45 91 7 47 02 48 70 44 69 47 02 42,59 44 98 43 84 48 44 47 66 50 62 46 47 48 73 8 47 50 51 01 47 27 51 65 44 67 48 02 47 37 48 37 4804 53 04 46 97 50 16 9 48 27 50 74 48 34 53 51 49 84 52 86 4685 49 39 46 67 51 62 46 41 50 77 10 53 16 55 25 47 74 52 05 50 86 54 21 4604 5273 46 03 57 03 4800 4952 11 50 11 55 56 48 13 46 79 5057 53 85 — — — — 54 10 54 00 12 — — — 57 00 — 54 00 — — — — 55 07 — Parameter L,: 50 06 5522 48 14 53 03 5236 58 40 47 26 5437 4821 66 25 58 69 56 34 sets tor K -0 47 -037 -0 47 -0 42 -025 -021 -0 38 -028 -0 38 -0 18 -0 19 -0 24 ofiginal data 'o 68 63 29 61 -0 30 42 10 -0 09 26 -061 -1 18 -0 75 . Percent Mean no occur- ind- occur- indi- Zooplankton category rence viduals rence viduals Fofaminrferans' 43 29 too 189 Polychaeies^ 29 0.5 too 73 Gas(ropods= 57 1 too 7.0 Ostracods^ 00 86 1 7 CalanoKJ copepods^ 00 too 17.7 Cydopoid copepods 00 43 14 HarpacOcoid copepods' 00 too 31 Mysids oo 14 0.1 Cumaceans 00 29 06 Tanaids^ 0.0 86 11.9 Isopods^ 00 71 3.0 Cimpedian larvae 0.0 29 0.6 Gammarid amphipods- 0.0 100 40 1 Caprellrd amphipods 0.0 43 1.0 Candean larvae 00 43 609 Candean adults and juveniles 0.0 86 18.4 Reptaniian zoea 00 57 17 Brachyuran megalops 00 71 6.3 Anomuran glaucothoe 00 43 1.3 Chaeiognaths'" 00 57 59 Ascidian larvae 00 14 1.0 'All foraniinifefans were eittier Tretomphalus sp. {72*'-o) or Amphistigina sp. (28%) ^The rnapr polychaete was Polyophthalmus sp. ^Included one 8-mm dond opisttiobranch: the rest were prosobranchs ' 3 mm long 'The major ostracod was a species of Cytindroleberdinae -All identifiat>le calanotds were Paramisophna sp . probably undescnbed (Abraham Remingef, SCTipps Institution of Oceanography. LaJolla, CA 92038. pers commun Apnl 1978) 'All identified harpacticoids were of a species of the family Peltidndae 'All the tanaids appeared to be of a species of Leptochefia. dose to L dubia (see Hobson and Chess 1976). 'Major isopods were Ciroiana sp., laniropsis sp.. Muma sp.. anthunds. and cryptoniscid larvae 'Gammands included Aoroides sp . Dexaminoides ohentahs, UIgeborgia sp.. a eusind, an oedicefotid, and a phoxocephalid. '"All chaetognaths were Spadella gaetanoi (A. Alvanno. Fishery Biologist, Southwest Fishenes Center. NMFS. NOAA. La Jolla. CA 92038. pers com- mun Sept 1978) Discussion Our collections and collecting sites were too few to comprehensively quantify the zooplankters that emerge from the lagoon substrata at Kure anti Midway Atolls. Despite its limitations, how- ever, this study increases our understanding of the kinds of organisms that have this habit. Further- more, it indicates there may be serious problems with the more extensive studies of Alldredge and King (1977). Porter et al. il977), and Porter and Porter (1977). Certainly some of the differences between their samples and ours are unrelated to sampling prob- lems. We assume, e.g., that the zooplankton fauna at Kure and Midway Atolls is distinguishable from the zooplankton fauna in the more tropical latitudes of the western Pacific Ocean where the Alldredge and Porter groups studied. It is un- likely, however, that zoogeographic variations can account for certain of the more striking differences between their samples and ours. The predominant forms in their collections were calanoid and cy- dopoid copepods. Alldredge and King (19771 cal- culated that during the night a mean of 6.679 calanoids emerged from each square meter of the reef face, and Porter et al. (1977) reported that over 10.000 calanoids emerged during the night from each square meter of branching coral in their study area. In comparison, our night-long collec- tions from a variety of substrata, including coral, yielded a mean of only 17.7 calanoids/m^. Of course, we did not sample a well-developed reef Only two of our sites included living coral, and these were isolated heads tour traps required a bed of sand). So habitat features could have contrib- uted differences between the collections. Nevertheless, if one considers the species of calanoids and cyclopoids collected by Alldredge and King, there are strong indications that the large numbers reported were inflated by holo- planktonic forms. The only calanoids and cy- clopoids they identified were Acartia spp. and On- caea spp. Species of these two genera are exceed- ingly numerous in the water column during both day and night (see Emery 1968: Hobson and Chess 1976). and we question whether they could in fact assume a benthonic mode. As stated i Hobson and Chess 1 978:149 ) "We would expect organisms that live in the substrate by day to have morphological features reflecting this habit that distinguish them from holoplanktonic relatives at the generic level or higher." .Although the Porter group did not identify their calanoids and cyclopoids to lower taxa, they too sampled western Pacific reefs and so the copepods that similarly dominated their col- lections may well have been the same, or very similar, to those taken by Alldredge and King. All our calanoids, on the other hand, appeared to be referable to the little known genus Paramisophna (Abraham Fleminger, Associate Research Biologist, Scripps Institution of Oceanography, La Jolla, CA 92038, pers. commun. April 1978). This fact agrees with our contention that zooplankters which periodically enter the substrate should be morphologically distinctive. If the diurnal benthic mode of this species is a generic characteristic, which seems probable, then its poorly known status likely stems from failure to be sampled by standard plankton-collecting techniques. During a marine survey of the Palau Islands, Randall et al. (1978) attempted to measure the zooplankters that emerged from the sea floor using traps ". . . built according to the design of Porter 278 and Porter (1977)." Their samples, taken above coral and sand substrata, included far fewer copepods than the Alldredge and Porter collec- tions I but many more than ours»; nevertheless, they recognized the presence of holoplanktonic forms (e.g., siphonophores, crustacean and fish eggs, and fish larvae), which they assumed ". . . either swam ( or were carried ) under the base of the trap from the open water . . .." So we believe that the studies by the Alldredge and Porter groups are flawed by the unrecognized occurrence in their samples of organisms from the surrounding water column. At Enewetak .Atoll (Hobson and Chess 1978), we concluded that many of the zooplankters above lagoon reefs at night are visitors from the deeper water. If this cir- cumstance existed where Alldredge and Porter set their traps, then their collections probably in- cluded deep-water forms. If so, the figures pre- sented as measures of zooplankters that emerge from defined areas of particular nearshore sub- strata probably include not only holoplankters as- sociated by day with other nearshore substrata but also holoplankters from outside the nearshore realm. We consider our collectons conservative esti- mates of the numbers of organisms that emerge from the sampled substrata. It may be that some forms which ordinarily rise into the water column were inhibited by our trap, and undoubtedly some that rose into the trap found their way back to the sea floor. But we feel our trap should have been as effective in capturing emerging zooplankters as those used by the Alldredge and Porter groups. Possibly some strictly benthic forms entered our samples by climbing up the inside of the trap. The few prosobranch gastropods that were taken may have been trapped this way, although they were small enough to have been swept up into the water column by surge, or perhaps to possess some flota- tion device that periodically permits a planktonic mode, as is the case with certain foraminiferans (e.g., Tretomphalus and perhaps Atnphistigina). Significantly, most of the organisms collected be- long to groups that include forms we have col- lected in the water column at night elsewhere: e.g., the foraminiferan genus Tretomphalus (at Majuro and Enewetak Atolls: Hobson and Chess 1973, 1976): the polychaete genus Polyophthal- miis (at Enewetak Atoll: Hobson and Chess 1978); and the ostracod subfamily Cylindroleberdinae, the tanaid genus Leptochelia. the isopod genera Cirolana and Munna. and family Anthuridae, the gammarid genus Aoroides. and families Eusiridae, Oedicerotidae, and Phoxocephalidae I at Santa Catalina. southern California: Hobson and Chess 1976. in prepi. The forms that predomi- nated in our collections belong to groups that were only relatively minor elements in the Alldredge and Porter collections. Most, in fact, w^ere lumped by Porter et al. ( 1977) in their summarizing Fig- ure 2 as "miscellaneous." This is not because they took fewer of these forms than we did, but rather because copepods and larvaceans so dominated their collections. We believe that the major difference between our collections and those of the Alldredge and Por- ter groups is that we excluded organisms from the surrounding water column. Alldredge and King (19771 were aware that outside organisms could enter through the gaps around the base of their traps, but seemed more concerned about or- ganisms inside that might have escaped. They dismissed both possibilities as significant sources of error with the statement (p. 318 1 ". . . as many plankters may also enter the trap through these gaps as escape through them." But because these devices were, after all, traps, probably many more zooplankters came in than went out. And if in fact zooplankters entered the traps through these gaps, it seems certain that forms from the sur- rounding water, including holoplankters, were continuously captured. Porter et al. (1977) re- ported about 1.5 to 2 times as man\' zooplankters as did Alldredge and King. They attributed this difference to more effective methods and equip- ment, but their traps, tethered above the reef, may simply have been more readily entered by holo- plankters. This would also account for the rela- tively large numbers of zooplankters they trapped by day. Both studies may have suffered from a misconception about the movements of these or- ganisms. Alldredge and King doubted that many escaped through the gaps around the bases of their traps because they assumed (p. 3181". . . emerging plankton swim primarily upward . . .."The Porter group would seem to have based their trap design — inverted cones tethered above the bottom — on the same assumption. But while these animals certainly rise progressively higher in the water column after emerging from the sea floor, gener- ally they swim — some flit — in short, irregular tangents more horizontal than vertical (based on our direct observations of a wide variety of forms in many locations). In any event if holoplankton did enter these traps in significant numbers, then 279 the samples taken should not be presented as measurements of the forms that emerged from the underlying substrata. Ackniiw Iciljiiiicnts We thank Richard S. Shomura and his staff at the Southwest Fisheries Center Honolulu Laboratory, National Marine Fisheries Service, NOAA, and Robert T. B. Iverson, Southwest Re- gion, National Marine Fisheries Service, for their cooperation and logistic support. We also thank Robert Johanness, Hawaii Institute of Marine Biology; Abraham Fleminger, Scripps Institution of Oceanography; and Alan R. Emery, Royal On- tario Museum, Canada, for helpful comments on the manuscript. Kenneth Raymond, Southwest Fisheries Centei' La Jolla Laboratory, drew Fig- ure 1 and Alice Jellett, Southwest Fisheries Center Tiburon Laboratory, typed the manu- script. Littraturi- Cited Alldredge, a, L.. A.ND J. M. KlNC. 1977. Distribution, abundance, and substrate preferences of demersal reef zooplankton at Lizard Island Lagoon, Great Barrier Reef Mar. Biol. iBerl.l 41:317-333 Emery, a. R. 1968. Preliminary observations on coral reef plankton, Limnol, Oceanogr. 13:293-303. FLEMINGER. A. 1964. Distributional atlas of calanoid copepods in the California current region, Part I. Calif Coop. Oceanic Fish. Invest., Atlas 2, 313 p. Glynn, P W 1973. Ecology of a Caribbean coral reef The Ponies reef- fiat biotope: Part II. Plankton community with evidence for depletion. Mar. Biol. iBerl.i 22:1-21. HOBSON, E. S- 1968. Predatory behavior of some shore fishes in the Gulf of California. U.S. Fish Wildl. Serv.. Res. Rep, 73, 92 p. 1973. Diel feeding migrations in tropical reef fishes. Helgol. wiss. Meeresunters. 24:361-370. 1974. Feeding relationships of teleostean fishes on coral reefs in Kona. Hawaii. Fish. Bull.. U.S. 72:915-1031. 1975. Feeding patterns among tropical reef fishes. Am. Sci. 63:382-392. HOBSON, E. S., .AND J. R. CHESS, 1973. Feeding oriented movements of the atherinid fish Pranesus pinguis at Majuro Atoll, Marshall Islands. Fish. Bull., U.S. 71:777-786. 1976. Trophic interactions among fishes and zooplankters near shore at Santa Catalina Island, California. Fish. Bull., U.S. 74:567-598. 1978. Trophic relationships among fishes and plankton in the lagoon at Enewetak Atoll, Marshall Islands. Fish. Bull., U.S. 76:133-153. Porter, J. W, 1974. Zooplankton feeding by the Caribbean reef-building 280 coral Montastrea carenosa. Proc. Second Int. Coral Reef Symp. 1:111-125. Porter, J. W., ..wd K. G. Porter. 1977. Quantitative sampling of demersal plankton mi- grating from different coral reef substrates. Limnol. Oceanogr. 22:553-556. Porter, J. W.. K. G. Porter, .and Z. B.-\t.m'-C.\t.-\l.an. 1977. Quantitative sampling of Indo- Pacific demersal reef plankton. Proc. Third Int Coral Reef Symp. 1:105-112. RAND.'\LL, R. H., C. BIRKEL.AND, S. S. AMESBURY, D. LASSUY, AND J. R. EADS. 1978. Marine survey of a proposed resort site at Arakabe- san Island, Palau. Univ. Guam Mar. Lab. Tech. Rep. 44, 66 p. edmund s. hobson James R. Chess St}uthuesl Fcsfwrtes Center Tthuron Laboratory National Marine Fisheries Seruice, NOAA 3150 Paradise Drive Tihuron.CA 94920 A SIRVEV OF HEAVY METALS IN THE SL'RF CLAM, SPISVLA SOI.IDISSIMA. AND THE OCEAN QUAHOG, ARCIICA ISLANDICA, OF THE MID-ATLANTIC COAST OF THE UNITED STATES Since the mid-1940's, two varieties of clams have become increasingly important to the seafood in- dustry, the surfclam, Spisula solidissima , and the ocean quahog, Arctica islandica. Surf clams and ocean quahogs are marketed primarily by the canning industry in chowders or as minced clams, as well as in a number of specialty products, such as cakes, patties, and dips. Prior to World War II, however, these clams had been used only as ani- mal feed or fertilizer. A commercial surf clam fishery developed rapidly with an annual harvest of 5L4 million pounds of meats in 1977 (Hutchi- sonM and a peak harvest of 96.1 million pounds of meats in 1974 (Bell and Fitz Gibbon 1977). The ocean quahog fishery developed more slowly. It was not until the 1970's that a vigorous commer- cial ocean quahog fishery developed, primarily to supplement the dwindling supplies of more desir- able clams, in particular, the hard clam, Mer- cenaria inercenaria: the soft-shell clam, Mya arenaria; and the surfclam (Anonymous 1971). The ocean quahog harvest in 1977 of 16.4 million 'Roger Hutchison, U.S. Department of Commerce. Economic and Marketing Research Division. Washington, DC, pers. commun. February 1978. FLSHERY bulletin vol 77. NO 1. 1979. pounds of meats (Hutchison see footnote 1), how- ever, represents a small fraction of an estimated sustained yield of 86 million pounds of meats an- nually (Rinaldo-^). Since surf clams and ocean quahogs have re- placed many traditional species, studies are needed that reflect their economic importance. It is well documented that many molluscs, including surf clams and ocean quahogs, concentrate heavy metals (Brooks and Rumsby 1965; Pringle et al. 1968; Waldichuk 1974). Boyden ( 1973) stated that one of the nutritious qualities of shellfish may be their high metal content. However, heavy metals exhibit toxic effects that affect all life stages of shellfish, especially development stages (Cala- brese et al. 1973; Calabrese and Nelson 1974; Thurberg et al. 1975). Considerable research has been done on effects of heavy metals on more popu- lar species of bivalve molluscs, especially the American oyster, Crassostrea virginica, hard clams, and soft-shell clams (Calabrese et al. 1973; Calabrese and Nelson 1974; Thurberg etal. 1974). However, until recently, there has been little in- terest in surf clams or ocean quahogs. Concentra- tions and concentration factors for a number of metals, including cadmium, chromium, copper, lead, nickel, and zinc, have been given by Pringle et al. (1968) and Pringle and Shuster^ for surf clams taken from Atlantic coast waters (Maine through North Carolina). Thurberg et al. (1975) exposed larval, juvenile, and adult surf clams to sublethal doses of silver and measured both physiological responses and bioaccumulation. Re- searchers at the U.S. Environmental Protection Agency (EPA), Narragansett, R.I., have exposed ocean quahogs to low concentrations of cadmium and monitored toxicological, biological, and his- topathological effects, as well as bioaccumulation (Zaroogian''). Bioaccumulation distribution pat- terns associated with industrial and sewage sludge dumpsites southeast of Delaware Bay have been monitored in ocean quahogs by scientists at the EPA, Annapolis, Md. (Lear and Pesch 1975). Awareness, then, of the importance of these ^Rinaldo. R. G. 1977. Atlantic clam fishery management plan. Environmental impact statement: Mid-Atlantic and New England Regional Fisheries Management Councils. Available Fisheries Management Division, National Marine Fisheries Service, NOAA, State Fisheries Pier, Gloucester. MA 019:30. ■'Pringle, B. H.. and C. N, .Shuster, Jr. 1967. A guide to trace metal levels in shellfish. USDHEW, Public Health Serv.. Shellfish Sanit. Tech. Rep., 18 p. ■* Gerald E. Zaroogian. U.S. Environmental Protection Agency. Environmental Research Laboratoi-y. Narragansett, RI 02882, pers. commun. February 1976. species is developing, but clearly more research is needed for such an important commercial shellfishery. Nine metals were chosen for analysis: arsenic, cadmium, chromium, copper, lead, mercury, nick- el, silver, and zinc. Based upon estimates of global metal production and oceanic sedimentation rates, Bowen (1966) divided 38 metals into their pollution potentials. He categorized cadmium, chromium, copper, lead, mercury, silver, and zinc as very high potential pollutants and arsenic and nickel as moderate. Goldberg (1972) emphasized the need for measurement in benthic organisms of the most potentially hazardous trace metals. MatcriaU and Methods Sampling The area of this survey extended from approxi- mately Montauk Point, N.Y., to Cape Hatteras, N.C., and seaward to approximately the 20- fathom contour. The survey encompassed the southern distribution of both surf clams and ocean quahogs in the United States. Samples were col- lected at 151 stations for chemical analysis (Fig- ure Din June and August 1974, aboard the NOAA ship Delaware II (MARMAP'^). A small hydraulic surf clam dredge, modeled closely after larger commercial dredges, was used throughout the survey. At each station 4-6 clams of marketable size were dissected, using stainless steel equip- ment. The foot was removed from each animal, drained, then combined and frozen in plastic bags. At the laboratory the tissues were homogenized in an electric blender equipped with a glass jar and stainless steel blades then stored for analysis in plastic ointment jars. All containers and equip- ment were acid-washed prior to use. Analysis Mercury analysis was performed on a Perkin- Elmer Model 305" atomic absorption spectropho- tometer fitted with a 25 X 150 mm absorption cell with silica end windows, using the flameless method of Greig et al. (1975). Arsenic analysis, performed on a Perkin-Elmer Model 403 atomic absorption spectrophotometer. =MARMAP 1974. Surf clam survey, cruise report, NOAA ship Delaware II. 1.3-28 June 1974 and "5-10 August 1974, 9 p. •^Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. 281 41° - 40° 39° 38° 37° - 36° - 6 I 76° 75° 74° 73° 72° FlCUKE 1. — Station location and number relative to the mid-Atlantic coast of the United States. 282 using a nitrogen/hydrogen flame, required an im- provisation of two simple interconnecting adapt- ers. The first, attached directly to the instrument, consisted of the female portion of a polyethylene quick disconnect (Nalgene 6150) and a nylon elbow hose connector threaded to fit the auxiliary inlet of the burner assembly. The second consisted of the male portion of the quick disconnect and a gas outlet adapter ( Rentes K- 183000). Both adapters were assembled with minimum length and bore of Nalgene tubing. The following proce- dure was used: A 5-g sample of tissue was placed into a 250-ml beaker to which 10 ml Mg(N03)2 • 6H2O (200 g/1) and 10 ml concentrated HNO3 (Baker 9603) were added. The mixture was covered with a watchglass and evaporated to dry- ness on a hot plate (130°-140°C). It was then placed into a cool mufflle furnace and the temperature raised in steps, first to 250°C for 3 h, then to 400''C for 3 h, and finally to550°C for approximately 15 h. After the beaker was completely cool, 15 ml of concentrated HCL ( reagent grade) were added and the resulting solution transferred to a 25-ml vol- umetric container and brought to volume with distilled water. A 10-ml aliquot of this solution was placed into a 24/40 jointed, 50-ml Erlenmeyer reaction flask and 2 ml of 15% (wt/vol) freshly made KI solution and 2 ml of freshly made StClj solution (20% [wt/vol] in 1:1 concentrated HCL:water) were added, waiting 2 min after each addition. Then 10 ml ofdistilled water were added. Five (5.00) grams of granular (20 mesh, no fines) low arsenic zinc (Fisher Z-15) were placed into the elbow of the second adapter, as noted above, and attached to the first adapter. This assembly was quickly inverted while attaching it to the reaction flask. The arsine generated was then analyzed at the instrument, which was equipped with a 3-slot burner and background corrector. Use of a record- er combined with full noise filtration and slow gas evolution contributed to a smooth and reproduc- ible peak upon which calculations were based. The reaction flask and the first adapter can be quickly removed for cleaning and reuse. Analysis of the remaining metals, also per- formed on the Perkin-Elmer Model 403, resembled thatof Middleton and Stuckey (1954): A sample of tissue ( 10 g wet weight) was weighed into a 250-ml beaker and 10 ml of concentrated HNO3 (Baker 9603) were added. The beaker was covered with a watchglass and heated to approximately 130°- 140°C on a hot plate until the liquid evaporated. One to two milliliters of concentrated HNO3 was added and the evaporation repeated. Again, 1-2 ml of acid was added but evaporated at 350°C or more. The hot plate was cooled and the latter acid addi- tion and evaporation was repeated until ashing was complete. The residue was dissolved in and taken up to 25 ml with 10% (wt/vol) reagent grade HNO3 after filtration through Whatman No. 2 paper. The solution was then analyzed directly in an air/acetylene flame by conventional atomic ab- sorption spectrophotometry. Results Greater average concentrations of silver, arse- nic, cadmium, copper, and zinc (122, 44.5, >230, 56.0, and 10.9% greater, respectively) were found in ocean quahogs than in surf clams for the entire survey (Table 1). Concentrations of several metals in both clams decreased southward. Concentra- tions of silver decreased steadily from 2.62 to 0.58 ppm in ocean quahogs and 1.63 to 0.19 ppm in surf clams. This is a 4.5- and 8.6-fold decrease, respec- tively, from the northernmost range of latitude to the southernmost. Concentrations of arsenic also decreased steadily, 1.6-fold, from 3.90 to 2.41 ppm in ocean quahogs. Although a steady decrease in arsenic concentrations was noted for a full 2.5° of latitude, a distinctive trend for the entire range of latitude was not evidenced. Copper concentrations in ocean quahogs decreased 2.5-fold from 7.16 to 2.84 ppm and zinc concentrations in surf clams decreased 2.0-fold from 18.5 to 9.1 ppm. Concen- trations of cadmium and zinc in the ocean quahog and copper in the surf clam did not exhibit any statistically significant trends, while the data for the remaining metal-clam combinations were in- sufficient for statistical analysis (Table 2). The results of Pringle and Shuster (see footnote 3) for cadmium and zinc (<0.20, 12.39 ppm, wet weight, respectively) in surf clams are in general agi'eement with the mean results of our study. Their result for copper (2. 39 ppm) was lower, while chromium and nickel (2.57, 1.22 ppm, respec- tively) were higher. The collection area of the former study was defined only as Maine through North Carolina; hence, geographic variations might be expected. In addition, neither the number of stations nor of surf clams analyzed was stated. Conclusions While the Food and Drug Administration (FDA) 283 Table l. — Average' heavy metal concentrations (parts per million, wet weight) found in surf clams and ocean quahogs by latitude. n Ag As Cd Cu Zn Range of lal N X SE X SE X SE X SE 7 SE Surf clams 4r00-40>30' 3 1 63 1 11 238 146 ■0,12 3 83 786 97 674 40 30 -40 00 6 1 42 329 263 234 0,13 008 287 216 18,5 481 40 00-39 30- 11 1 18 140 239 120 013 010 296 348 183 1 14 3930-39-00 11 1,05 ,130 2 17 200 15 015 3 45 226 148 1 1 1 39 00-38 00 13 0.94 ,120 1 91 131 ■0 13 338 211 11 3 485 38 30-38 00 13 050 082 1 57 082 ■:0,11 2 97 259 106 188 38 00-37 30 8 51 081 2 08 145 -0,12 354 360 9 1 253 37 30-37 00 11 44 071 222 122 -.0,12 3 48 478 94 228 3700 -36 30 14 32 046 2 17 233 <0,14 3 08 228 93 260 36 30 -36 00 3 019 053 1 46 082 .■;0,14 2 88 262 96 153 41 00-36 00 93 76 2 08 13 3 23 11 9 Ocean quahogs 41 00-40 30 8 262 400 3 90 374 054 069 7 16 837 126 0.518 40 30-4000 15 2,49 376 3 36 293 42 034 5 33 401 14.5 1.04 40 00'-39 30 9 1,53 296 2 97 171 42 035 4 71 348 139 741 3930-39'00 9 1,29 ,138 2 68 236 39 035 4 41 280 124 991 3900-3830' 5 1,21 371 2 65 114 42 059 5 10 727 132 806 38 30-36 30 6 058 120 241 326 39 051 2 84 434 10 4 1,38 41"00-36 30 52 1 69 3 01 43 504 132 'Average of n samples with 4-6 clams per sample Table 2. — Average' heavy metal concentrations ipartsper mil- lion, wet weight) found in surf clams and ocean quahogs by latitude. Range of lat N n Cr Hg Ni Pb Surf rlams 41-00-40 30 3 62 • 05 _ • 07 40 30-40 00 6 95 07 71 • 07 40°0O-39 30 11 70 08 39 07 39=30-3900 11 069 ■0 08 080 • 07 39°00 -38 30 13 065 ■0 08 60 7 38°30 -38 00 13 061 08 ■0 50 • 06 3B"00-37 30 8 -0 53 08 — • 07 37°30-3700' 11 49 • 007 — ■07 3700-36 30 14 -,0,48 •0,06 _ •07 36"30'-36 00' 3 • 0,48 •:0,05 — - 7 41 00-36 00' 93 061 07 59 7 Ocean quahogs 41 00 -40 30 8 1 03 ■0 09 91 18 40°30 -40 00 15 • : 1 ,23 - 06 062 1 40 00 -39 30 9 70 ■0 06 - 50 12 39'30-3900 9 80 07 0,50 09 39 00-38 30 5 10 008 055 • 1 2 38'30-36 30 6 1 1 ■006 059 • 09 40 00 -Se 30' 52 1 ■:006 <:061 • 1 1 'Average of n samples with 4-6 clams per sample has not set standards for heavy metals in U.S. fishery products (except mercury), the National Health and Medical Research Council (NHMRC) of Australia has recommended maximum con- centrations for a number of metals in seafoods (Mackay et al. 1975). Concentrations of cadmium, copper, lead, and zinc found in surf clams and ocean quahogs were well under these limits (2.0, 30, 2.0, 1,000 ppm, wet weight, respectively) and far below levels found in American oysters har- vested from Atlantic coastal waters (Pringleet al. 1968). The NHMRC recommendation of 1.14 ppm (wet weight) arsenic! 1.5 ppm as ASjOg). however, was exceeded at all but a few sampling stations. Mean arsenic concentrations for all stations were 2.1 ppm in surf clams and 3.0 ppm in ocean quahogs. The distribution of arsenic concentra- tions did not vary greatly with latitude and may indicate that background levels along the mid- Atlantic coast are higher than those in Australian waters. Concentrations of mercury were found to be well below the action limitset by the FDA (0.50 ppm, wet weight). Major fishing grounds for the surf clam industry are located off the New Jersey and Virginia coasts. Since data for mercury presented in this study are well within the existing guideline set by the FDA for U.S. fishery products and, with a single excep- tion, within the more extensive NHMRC recom- mendations for Australia, there should be little concern to consumers for surf clams or ocean quahogs harvested from these areas at present. The latitudinal cline demonstrated in this study should, however, stimulate further interest in heavy metal inputs along the mid-Atlantic coast of the United States. Data indicate that a large area of our eastern coast may be affected by the pres- ence of heavy metals. The effect on clams is impor- tant, particularly since surf clams and ocean quahogs are representative of the important shellfisheries located in this area. Literature Cited ANONYMOU.S. 1971. Ocean quahog becomes more important as surf and bay clams dwindle, Commer, Fish. Rev. 33l4):17-19. 284 BELL, T. I.. AND D. S FITZ GlBHDN (editors). 1977. Fishery statistics of the United States 1974. U.S. Dep. Commer.. NOAA, Natl. Mar. Fish. Serv.. Stat. Dig. 68, 424 p. BOWEN, H. J. M. 1966. Trace elements in biochemistry. Academic Press, N.Y., 241 p. BOYDEN. C. R. 1973. Accumulation of heavy metals by shellfish. Proc. Shellfish Assoc. G.B., 4th Shellfish Conf., p. 38-48. BROOKS, R. R., .■\ND M. G. RUM.SBY. 1965. The biogeochemistry of trace element uptake by some New Zealand bivalves. Limnol. Oceanogr. 10:521-527. Calabrese, a., R. S. Collier. D. a. Nelson, and J. R. MacInnes. 1973. The toxicity of heavy metals to embryos of the American oyster Crassoslrea virginica. Mar. Biol. (Berl.) 18:162-166. Calabrese, a., and D. a. Nel.son. 1974. Inhibition of embryonic development of the hard clam, Mercenaria njercenaria, by heavy metals. Bull. Environ. Contam. Toxicol. 11:92-97. Goldberg, E. G. (convener!, 1972. Marine pollution monitoring: strategies for a na- tional program. Deliberations of a workshop held at Santa Catalina Marine Biology Laboratory, Univ. South- ern Calif, Allan Hancock Found., Los Ang., Calif., 203 p. GREIG, R. a., D. Wenzloff, and C. SHELPUK. 1975. Mercury concentrations in fish. North Atlantic offshore waters— 1971. Pestic. Monit. J. 9:15-20. Lear, D. W., and G. G. PESCH (editorsi. 1975. Effects of ocean disposal activities on mid- continental shelf environment off Delaware and Mary- land. Environmental Protection Agency, Region III, Phila.. Pa, 204 p. MACKAY, N. J., R. J. WILLL-WIS, J. L. KACPRZAC, M. N. Kazacos, a. J. Collins, and E. H. Alty. 1975. Heavy metals in cultivated oysters iCrassostrea commercialis = Saccostrea cuculhta) from the estuaries of New South Wales. Aust. J. Mar. Freshwater Res. 26:31-46, Middleton, G., and R. E. Stuckey, 19.54. The preparation of biological material for the de- termination of trace metals. Part II. A method for the destruction of organic matter in biological mate- rial. Analyst 79:138-142. PRLNGLE, B. H,, D. E. HiSSdNG, E. L. KaTZ, and S. T. MULAWKA. 1968. Trace metal accumulation by estuarine mollusks. Proc. Am. Soc. Civil Eng., J. Sanit. Eng. Div. 94:455-475. Thurberg, F. p., W. D. Cable. J. R. MacInnes. and D. R. Wenzloff. 1975. Respiratory response of larval, juvenile, and adult surf clams. Spisiila ^olidissima, to silver. In J. J. Cech. Jr.. D. W. Bridges, and D. B. Horton (editors). Respiration of marine organisms, p. 41-52. TRIGOM Publ., South Portland, Maine. THURBERG, F. p., a. Calabrese, and M. a. Dawson. 1974. Effects of silver on oxygen consumption of bivalves at various salinities. In F. J. Vemberg and W. B. Vern- berg (editorsi. Pollution and physiology of marine or- ganisms, p. 67-78. Academic Press, N.Y. Wai.dkhuk. M. 1974. Some biological concerns in heavy metals pollu- tion. In F. J- Vernberg and W. B. Vernberg (editors). Pollution and physiology of marine organisms, p. 1-57. Academic Press, N.Y. D R. Wenzloff R. A. GREIG NorlheasI Fiaheries Center Milford Laboratory National Marine Fisheries Seniice. NOAA Milford. CT 06460 A. S. MERRILL J. W. Ropes Northeast Fisheries Center Woods Hole Laboratory National Marine Fisheries Service. NOAA Woods Hole. MA 02543 APPARENT FEEDING BY THE FIN WHALE, BALARNOPTERA PHYSALUS. AND HLIMPBACK WHALE, MEGAPTERA NOVAENGLIAE, ON THE AMERICAN SAND LANCE, AMMODYTES AMERICASLS. IN THE NORTHWEST ATLANTIC On 18 May 1977 a large group of fin, Balacnoptera p/!V.sa/(/.s. and humpback, Megaptera novaengliae, whales was observed on Stellwagen Bank north of Cape Cod (lat. 42"26'N, long. 70°26'W) by North- east Fisheries Center (NEFC) personnel conduct- ing an annual spring bottom-trawl survey aboard the National Oceanic and Atmospheric Adminis- tration RV Albatros.v IV. Nine fin and 14 humpback whales were identified and observed near the vessel. More whales were sighted in the vicinity, but were too far away to identify posi- tively or to observe conveniently. Many great black-back. Larus marinus, and herring, Lariis argcntatus, gulls were seen feeding at the surface and circling around the whales. The whales dis- played a characteristic feeding behavior described by Gunther ( 1949) and mentioned in Katona et al. (1975). The animals we observed were circling, spouting often, making short shallow dives, and not moving in any set direction. They behaved in a leisurely manner and were seemingly undis- turbed by our presence as noted by Gunther ( 1949). Echo sounding traces indicated a depth of 40 m in this area and large patches of densely concentrated small fishes throughout the water column, but particularly near the surface. During several 30-min bottom-trawl tows in the area, up to 400 kg of adult American sand lance, Ainiuo- FISHERY BULLETIN VOL 77. NO 1. 1979 285 (lytes anwncaiius, were netted per tow (Northeast Fisheries Center') with Atlantic cod, Gadus morhua, and spiny dogfish, Squalus accinthias, the only other abundant fish species. An examination of several cod stomachs showed them to be packed with sand lance while a similar inspection of sand lance showed them to be feeding on copepods. It is our contention that the abundance and behavior of whales in this area indicates that they were feed- ing on a concentration of American sand lance. Similar whale feeding behavior had been previ- ously observed on 18 June 1976 with a humpback whale located at lat. 42°09'N, long. 70°10'W, and with a fin whale located at lat. 42°04'N, long. 70°20'W, and on 20 June 1976 with a humpback whale located in the same general area ( Northeast Fisheries Center'^). During these three observa- tions many herring gulls were again seen feeding at the surface and circling around the whales. Large numbers of American sand lance were also visually observed at the surface by NEFC person- nel aboard the Alpine Geophysics RV Atlantic Twin and in the water column again by NEFC personnel aboard the General Oceanics research submersible Nekton Gamma. These latter two vessels were involved in testing the feasibility of using a research submersible to survey marine organisms (Northeast Fisheries Center-'). Bigelow and Schroeder 11953) reported that fin whales were observed feeding on American sand lance that were abundant in Cape Cod Bay in 1880. Nemoto (1959) listed American sand lance as one of the food items of baleen whales of the North Pacific, along with a variety of other fishes and euphausids. Fin and humpback whales are reported to feed on capelin, Mallotus villosus, a fish similar to the American sand lance in size, summer habitat, and schooling behavior in the continental shelf waters off Nova Scotia and New- foundland (Mitchell 1974a). Fin whales landed at Blandford, Nova Scotia, from 1967 to 1972 con- tained sand lance (May- August), and stomachs from Newfoundland fin whales had >1% sand lance (June-July) in 1970-1972 (Mitchell 1974b). There is little stomach analysis data, though, from baleen whales captured in New England waters in 'Northeast Fi.sheries Center. 1977. Cruise Results. NOAA R/V ALBATROSS IV. Cruise No, 77-02. Spnng Bottom Trawl Survey: Part III. Woods Hole, Mass.. 6 p. ^Northeast Fisheries Center. Gulf of Maine whale sighting network reports Groundfish Survey Unit. Data on tile. Woods Hole, Mass. ^Northeast Fisheries Center. 1976. Cruise Results, R/V At- lantic Twin, Cruise 76-01, Woods Hole, Mass., 8 p. the late 1880's when whaling was popular (True 1904), and no such data since the early 1900's when, for all practical purposes, whaling had ceased. Thus, it is difficult to confirm exactly what fin and humpback whales in the Cape Cod region eat. The feeding observations which we made imply that the rorqual whales off New England, particu- larly fin and humpback whales, may be utilizing the high standing stock of American sand lance that is currently available (Northeast Fisheries Center''). Additionally noteworthy is that the At- lantic herring, Clupea h. harengus, a commonly mentioned rorqual whale food (Allen 1916; Inge- brigtsen 1929; Bigelow and Schroeder 1953; Nemoto 1959), is in low abundance at this time (International Commission for the Northwest At- lantic Fisheries 1976). I.itirature Cited AU.EN, G. M. 1916. The whalebone whales of New England. Mem. Boston Soc. Nat. Hist. 8(2), 322 p. BiiiKLOw, H. B., .^ND W, C. Schroeder. 1953. Fishes of the Gulf of Maine. U.S. Fish Wild! Serv.. Fish, Bull, 53. 577 p, GUNTHER, E, R. 1949. The habits of tin whales. Discovery Rep. 25:115- 141. INTERN.ATIONAI, COMMISSION FOR THE NORTHWEST ATLAN- TIC FISHERIES. 1976, Report of standing committee on research and statistics iSTACRESi. Eighth special commission meet- ing-January 1976. Appendix II, Report ofaf//ioc working group on herring- Int, Comm, Northwest Atl, Fish,, Redb, 1976:35-50, INGEBRIGTSEN, A, 1929. Whales caught in the North Atlantic and other seas. Rapp, P,-V, Reun, Cons. Perm, Int, Explor, Mer 56, 26 p Katona, S., D, Richardson, and R, H.v.ard. 1975. A field guide to the whales and seals of the Gulf of Maine, Maine Coast Printers, Rockland. 97 p. Mitchell. E, 1974a. Present status of Northwe.st Atlantic fin and other whale stocks. In W. E. Schevill (editor). The whale prob- lem, a status report, p, 108-169, Harv, Univ. Press, Camb,. Mass. 1974b, Trophic relationships and competition for food in Northwest Atlantic whales. In M, B. U, Burt (editor), Proceedings of the Canadian Society of Zoologists annual meeting, June 2-5, p, 123-133, Nemoto, t, 1959, Food of baleen whales with reference to whale movements. Whales Res, In.st. Sci, Rep, 14:149-290, ■•Northeast Fisheries Center, Spring groundfish survey re- search cruises 1967-1977. Groundfish Survey Unit. Data on file, Woods Hole, Mass. 286 True, f. w. 1904. The whalebone whales of the western North Atlan- tic compared with those occurring in European waters, with some observations on the species of the North Pa- cific. Smithson. Contrib. Knowl. 33. 332 p. William J. Overholtz John R. Nicolas Northeast Fisheries Center Woods Hole Laboratory National Marine Fisheries Service, NOAA Woods Hole. MA 02543 entire low tide period, since only a single count was made sometime between 90 min before and 90 min after low tide. This study was initiated in fall 1973 in an effort to determine the availability of crabs and the magnitude of intertidal harvest on one high-use Puget Sound beach. From data collected, an esti- mate was made of the total use of Puget Sound beaches by sport crabbers for daylight low tides in 1974. Methods ESTIMATION OF INTERTIDAL HARVEST OF DUNGENESS CRAB, CANCER MAGISTER, ON PUGET SOUND, WASHINGTON, BEACHES' There are two major methods employed in the sport fishery for the Dungeness crab. Cancer magister, in Puget Sound, Wash. The first is a passive method. A baited pot, trap, or ring net is placed on a subtidal substrate, left for a period of time, and retrieved. The second is an active method. During periods of low minus tides, sport crabbers seek crabs by sight. The crabbers usually wade out into water between knee and waist level, then walk parallel to the beach. A round metal loop, about 1 ft in diameter, covered with wire mesh and attached to a long handle, is generally used to capture crabs. Beginners often bring fish nets, but find it difficult to extricate the crabs caught in the net. When a crab is seen, the crabber maneuvers the hoop quickly under the crab. The crab's legs go through the mesh, making escape difficult, and the hoop is then pulled from the wa- ter. Only male crabs may be taken, and they must be a minimum of 152 mm (6 in) in width, as deter- mined by a caliper measurement across the carapace, directly in front of the 10th anterolat- eral spines. The daily crab catch is limited to six per person. Knowledge of the size and distribution of the intertidal sport fishery was limited until 1969, when the Washington Department of Fisheries began aerial surveys to estimate low tide usage of Puget Sound beaches for clam digging and crab- bing. By summer 1973, enough data had been col- lected to show which beaches were being used for crabbing. However, the aerial surveys did not reflect the total use of beaches by crabbers over the 'Based on work submitted in partial fulfillment of the re- quirements for the degree of Master of Science. FISHERY Bl'LLETIN VOL 77. NO I. 1979 From preliminary aerial survey data. Mission Beach, located 60 km north of Seattle and just beyond the Port of Everett, was selected as the study site (Figure 1). The beach is 3 km long, shallow, and sandy, with eelgrass beds below the mean lower low water (MLLW) level. This beach had only one public access, cut through a 15-m bluff. This location provided me with a good view of the entire area and made it possible to interview almost all crabbers using the beach. From October 1973 to October 1974 there were 19 low tide series with tides lower than -0.30 m MLLW. These tidal series occurred in all months of the year except March and September. I visited Mission Beach during all tides lower than -0.30 m, except under adverse weather conditions in the winter months. I arrived 2.25 h before low water and walked to point 'a' ( Figure 1 ), where I entered the water and moved toward the access at a depth of 0. 15 to 0.85 m through the area most intensively utilized by the sport crabbers. For all crabs ob- served, I recorded the size to the nearest millime- ter ( taken in a horizontal measurement directly in front of the anterolateral spines on the carapace, by means of a caliper) and sex. Sampling was by the method used by most crabbers. Beginning 2 h before low tide, I made half- hourly counts of the number of crabbers at the beach, but continued beach sampling of crabs until crabbers began to leave the beach, usually about 0.5 h before the low. At this time, I interviewed the crabbers about their success and time spent crab- bing. About 9(K of all crabbers using Mission Beach, on tides checked, were interviewed. During the interviews, I measured as many crabs as pos- sible. From the interview data, I estimated the number of crabbers on the beach at any time dur- ing a period of 14 min before to 15 min after the half-hourly counts. The average time spent crab- bing was slightly over 1.5 h; thus, if all crabbers 287 48*3' Figure l. — Location of Mission Beach within Puget Sound, Wash. The area most intensively utihzed by crabbers at Mission Beach is outhned with dashes. ia'i- BEACH / ^ 5»v , i^ ACCESS \ ^ i ' KILOMETERS DEPTH IN FATHOMS ^ T" 1 2 2* 30 had been interviewed, the constructed counts would coincide with actual beach use. However, not all crabbers were interviewed, so the half- hourly counts were more accurate for the lowest period of the tide when most people were crabbing. I then constructed a table for each month which assigned the highest of the two estimates, either the constructed count from the interviews or the half-hourly beach count, to each half-hourly period. The number of crabbers using the beach was computed for each tide by dividing the total crabber hours (the sum of the half-hourly counts) by the average hours spent crabbing (obtained from crabber interviews) and totaled for each month. From the monthly table, the number of crabbers on the beach at any half-hourly interval, divided by the total number of people using the beach for each month during the low tide period, gave a percentage of people using the beach at any 288 half-hourly count. Monthly use curves were then constructed for Mission Beach (Figure 2). The methods that I employed to develop use curves were similar to those that have been used by researchers who have dealt with other recrea- tional fisheries (Miller and Gotshall 1965; Brown 1969; Tegelberg^; Jarman et al.^). In addition to the sampling that I conducted at Mission Beach, personnel from the Washington Department of Fisheries Shellfish Laboratory conducted creel sampling at six other Puget Sound beaches having differing levels of crabber use. From the survey material that they provided, I had insufficient data to construct use curves for ^Tegelberg, H C 1963 The 1962 razor clam fisheries. State Wash. Dep. Fish . 28 p. =Jarman, R.. C Bennet, C. Collins, and B. Brown 1970. Angling success and recreational use of twelve state owned lakes in Oklahoma. Paper given at 21st Annu. Meeting South. Div. Am. Fish- Soc. New Orleans. La. 100^ ^ 90- /^•^ APR M»«JUN - = 80- ^'■■■"v JUL AUG — • S 60 / X:-, \\ ^ ^v •. *. S bO / \;^ \ ^ 40- / £ 30- <-'^-"^ n/- '■- \ ^ 20- xj>.. "\ S^ 10 X^.' _ **- PERIOD ABOUT LOW TIDE iMINUTES) Figure 2. — Crabber use curves for Mission Beach based on data gathered April-August 1974. April and August, but I was able to construct use curves for May -June and July, a combined total for those beaches based on 10 and 5 observations, respectively. These use curves, when superim- posed over the corresponding Mission Beach use curves, did not vary by more than approximately 10% for the period before, or 20^f for the period after, the low tide. The Washington Department of Fisheries also provided me with data from aerial surveys con- ducted over Puget Sound beaches on 27 April, 25 May, 22 June, and 20 July 1974. Most of the beaches were surveyed during the hour preceding the low tide, which corresponded to the highest beach use. Thus, the curves derived for Mission Beach were used for estimates for all beaches. While interviewing crabbers at Mission Beach, it appeared to me that both the tidal height and tidal sequence were important factors in crabbing success. I therefore analyzed the data in two dif- ferent ways. The various tidal series had from three to eight tides lower than -0.15 m(-0.5ft). I divided the low tide heights into six levels by 0.15-m increments. The first minus tide of a series to fall into a tidal height category was defined as Tide One in the tidal sequence. Each succeeding tide was consecutively numbered, with the final tide in a series designated as the last minus tide to fall into a tidal height category. Thus, low tides of equal height from different tidal series were not always the same sequence number. Results and Discussion The number of crabbers using Mission Beach during the winter nighttime tides was small com- pared with the number during the summer day- time tides. Of the estimated 762 crabbers using Mission Beach during the year, only 27 (4'7f) crabbed from October through February, while 735 (96% ) crabbed from April through August. Of the estimated 531 crabs taken for the year at Mis- sion Beach, the winter crabbers caught 60 (11%), while the summer crabbers caught 471 (89%). Stepwise multiple linear regression analysis (Poole 1974) of crabber activity at Mission Beach correlated significantly (P<0.05) with tide height, day of week, month, temperature, and wind veloc- ity (Table 1 ). However, the resultant equation was not strong enough for predictive purposes. The tide height accounted for the largest amount of the variability. The lowest three tide levels had two to four times as many crabbers as the highest three levels (Table 2). The other significant variables indicated the following: weekend use by crabbers per tide was 1.5 times greater than the average weekday use per tide; the average number of crab- bers per tide was highest in April, May, and June, with the use dropping off considerably in July and August; there were more crabbers at higher air Table L— Summary table of multiple linear regression be- tween total crabbers at Mission Beach and nine independent variables. The resultant equation was significant at P<0.001 for all steps. Variable Signif- Mult Overall step entered icance' R fl= R F 1 Tide height 0001 45 20 45 12 35 2 Day ol week 003 59 34 -027 1237 3 Month 005 67 45 -0 39 12 61 4 Temperature 007 73 53 26 12 92 5 Wind velocity 027 76 58 -006 12 37 6 Tide sequence 078 78 61 08 11 39 7 Previous day s catch/crabber 698 78 61 04 9 59 8 Precipitation 769 78 61 -0 06 8 21 9 Cloud cover 825 78 .61 -013 7 14 ^The Q level of significance for each variable as it was entered in the equation Table 2. — Crabber use and catch taken on six different tide heights (mean lower low water) at Mission Beach, Wash., Apnl-August 1974. Total Tide No ol Mean no Mean no Mean catch legal height tides crabbers of crabs legal crabs crab (m) sampled per tide caught per crabber catch -0 15 to -0 29 - 30 to -0 44 -0 45 10 -0 59 -0 60 to -0 74 -0 75 to -0 89 -0 90 to -1 04 6 14 16 6 13 9 25 27 1 4 79 6 1 24 7 150 54 02 06 07 1 3 06 02 7 110 92 173 62 27 289 temperatures, but this corresponded with the low- est tides in June, which occurred at midday; on days with high winds there were few crabbers. This was probably due to a lowered chance of suc- cess because waves on the beach made crabs difficult to see. The estimated use of the beach by crabbers cor- responded with the daily availability of crabs on the beach that I observed by sample crabbing. This availability appeared to be affected by current and tide height. Two hours before low tide, the water level over the eelgrass portion of the beach, where most crabs were found, was generally >1 m. As the tide went out and the water became shallower, I observed few crabs in water <0.15 m deep. The current also appeared to have effects. When the tide approached its lowest level, the current be- came slack, at which time I observed few crabs. Even on days when a large number of crabs were active an hour before the low, few would be evident at low slack. The monthly use curves enabled me to take a single aerial survey count of crabbers using a sur- veyed beach at any time during the low tide period and predict the total crabber use at the beach during the entire low tide period. I adjusted the total calculated Puget Sound beach use by crabbers during the 1974 aerial sur- veys by two factors: the number of crabbers excluded because beaches were not surveyed and the improper identification of people as crabbers who were not actually crabbing. Between 1969 and 1973, at least one aerial survey at low tide was conducted over every Puget Sound beach, and all important crabbing beaches were identified. From this data I estimated that the 1974 aerial surveys included 959( of the crabbers and other recreation- ists on the beaches at any given low tide. At the same time 1974 aerial surveys were made over Mission Beach, I made actual counts of crabbers on the beach. The average overcount of crabbers by the aerial survey was 15.5%. Total Puget Sound intertidal crabber use for all low tides from April through August was roughly estimated by dividing the total Mission Beach counts on the days of the aerial surveys, April through July, by the adjusted total Puget Sound beach count. The quotient was designated as the percentage of Mission Beach use relative to the adjusted total beach count (Table 3). Due to poor visibility on the day scheduled, no aerial survey was conducted in August, so I used averaged data from the preceding 4 mo. I estimated the total crabber use on all beaches for each month by divid- ing the percentage Mission Beach use of the total adjusted beach count into the total crabber use of Mission Beach for each month. In order to estimate the total crabs caught in Puget Sound by intertidal sport crabbers, I needed to know whether the average catch over a low tide period at other Puget Sound beaches was the same as that at Mission Beach. Six other beaches in Puget Sound that had different levels of crabber utilization were sampled on a random basis by personnel from the Washington Department of Fisheries. Their levels of crabber use ranged from a few to 70 crabbers per tide. Four of the six beaches had three or more surveys, and these were compared with Mission Beach by Wilcoxon Rank Sum Tests (Hollander and Wolfe 1973). The four beaches had W values of 13.5, 9.5, 46.5. and 106, which in all cases were greater than the computed values of 6, 6, 39, and 66. Thus the null hypothesis that there were equal catches per crabber at the different beaches could not be rejected. This im- plies that the number of crabbers at a beach is self-regulating in that crabbers tend to adjust their level of effort to the rate of return, and that rates of return for all crabbers at different beaches remains fairly constant. This same pattern of utilization was observed in the recreational trout fisheries in California lakes, where the angling effort adjusted proportionally to the numbers of catchable-size trout (Butler and Table 3.— Estimate of the total monthly crabber use in the intertidal Dungeness crab sport fishery for Puget Sound beaches, April-August 1974. — Percentage Adjusted total Puget No of crabbers at Mission Beach use Total crabbers Estimated total inler- Sound beach count on Mission Beach on of total adjusted beach count at (Col 5 - Col 4) Month monthly aerial survey monthly aerial survey (Col 3 - Col 2) Mission Beach April 433 27 6.2 79 1.274 May 829 28 3.4 229 6.735 June 954 33 3.5 279 July 805 29 36 121 3.361 August No observation '4 18 27 646 Total 735 19.987 'Average of four previous rnonths 290 Borgeson 1965). Since the catches did not differ significantly, all beaches were treated together for predictive purposes. An estimate of the total crabs caught by intertidal sport crabbers for the day- light tides in 1974 was made by multiplying the average catch per effort for April, May , June, July, and August at Mission Beach (Table 4) by the estimated total number of crabbers (Table 3) for each month. The number of crabs caught per month increased throughout the spring, reaching a maximum of 5,099 in June. Few crabs were caught after July (Table 5). When Spearman rank correlation coefficients were computed between a crabber's catch at Mis- sion Beach and a number of independent variables (Hollander and Wolfe 1973), the most significant positive correlation was with the total time spent crabbing (Table 6). Crabbing was better in April- June than in July and August. The tide height and tide sequence were not significantly correlated with the catch per crabber at P<0.05, but were significant at P<0.10. The highest average catches were on tides ranging from -0.60 to -0.74 m (Table 2). The higher tides make crabbing difficult, be- cause crabbers have to wade into deeper water to get to the area where crabs are found. In the deeper water, crabs are less visible and the mobil- ity of crabbers is impaired. The catches and number of crabbers arranged by tide sequence are shown in Table 7. The lowest tides of the year are generally four or five tides into a tidal series. The first low tides in the series have already allowed a fair amount of crabbing pressure on the beach, and many of the available crabs have been removed. Additionally, the combination of crabbers wading and less water over the beach on the previous low tides probably causes crabs to move to deeper water during the last low tides in a series. The sex and size composition of crabs that I observed while sampling are shown iti Figure 3. The numbers of legal males (152 mm and larger) include all crabs measured during crabber inter- TaBLE 4. — Monthly crabber use and mean daily catch at Mission Beach, Wash., Apnl-August 1974. Mean daily Range of Number of Number of catch per mean daily Montti tides crabbers crabber catches Table 5.— Estimated total Dungeness crab sport catch in Puget Sound on intertidal beaches. April-August 1974. April 5 79 1 76 4-3 May 11 229 86 0-3 4 June 14 279 64 0-2 2 July 14 121 59 0-1 7 August 6 27 30 0-0 5 Mean catch per Estimated Estimated crabber at total Pugel total crab Month IVtission Beach Sound crabbers catch April 1 76 1.274 2.242 May 86 6,735 5.792 June 64 7.971 5.099 July .59 3.361 1.983 August .30 646 194 Total 19,987 15,310 Table 6. — Spearman correlation coefficients between number of crabs caught per crabber and nine independent variables. Variable Time spent crabbing Month Tide height Tide sequence Wind velocity Temperature Precipitation Time of low Cloud cover Correlation coefficient 0738 -0413 229 -0,222 -0 175 -0 105 -0 092 054 0010 Significance 0001 002 .055 .061 .113 .238 .263 355 473 Table 7. — Crabber use and catch taken on different tide heights arranged according to the sequence in which they occurred in a low tide series at Mission Beach. Wash., April-August 1974. No of Mean no Mean no Mean catch Total Tide tides crabbers of crabs legal crabs legal sequence sampled per tide caught per crabber crab catch 1 6 15 76 0,5 46 2 9 23 103 0,9 163 3 8 13 9,4 0,7 85 4 8 13 6,5 0,5 52 5 8 9 89 10 71 6 7 18 63 04 44 7 3 14 27 02 8 8 1 20 20 1 2 2251 100 75- 50^ 25- MAIESQ FEUIAIESQ JL <108 114 121 12; 133 140 146 152 159 165 171 178 184 < LENGIH mm) Figure 3, — Size composition and sex of crabs observed during sample crabbing at Mission Beach from October 1973 through August 1974, Male crabs -">150 mm include those measured during crabber interviews. 291 In summary, the use of Mission Beach by inter- tidal crabbers is greatest 1 to 2 h before the low tide. This corresponds to the period when crabs are most readily observable. From the data collected at Mission Beach and aerial survey counts of other Puget Sound beaches, I estimated that about 20,000 crabbers utilized intertidal beaches from April through August 1974. The intertidal Dungeness crab sport fishery is, however, fairly small compared with other marine sport fisheries in Puget Sound. Acknowledgments I wish to thank G. Pauley, J. Congleton, C. Woeike, K. Chew, and T. Walker for discussion and critical readings of various stages of the man- uscript. Reviewers for the Fishery Bulletin helped improve the readability. R. Whitney, as Leader of the Washington Cooperative Fishery Research Unit at the University of Washington, provided encouragement, support, and facilities from the outset of the study. Appreciation is extended to A. Scholz and other members of the Sport Shellfish Section of the Washington State Department of Fisheries, without whose cooperation this study would not have been possible. The study was par- tially supported by funds from the Washington Department of Fisheries. Literature Cited BROWN, B. E. 1969. An analysis ofthe Oklahoma State lakecreel survey to improve creel survey design. Ph.D. Thesis, Oklahoma State Univ., 164 p. Butler, R. L., and D. P. Borgeson. 1965. California "catchable" trout fisheries, Calif Dep. Fish Game, Fish Bull. 127. 47 p. Hollander. M., and D. a. Wolfe. 1973. Nonparametric statistical methods. John Wiley and Sons. N.Y.. 503 p. MILLER, D. J., AND D. GOT.SHALL. 1965, Ocean sportfish catch and effort from Oregon to Point Arguello, California, July 1, 1957 to June 30, 1961, Calif Dep, Fish Game, Fish Bull. 130. 135 p Poole, R. w 1974, An introduction to quantitative ecology. McGraw-Hill. Inc., N,Y,. 5.32 p, JOHN G, Williams Washington Cooperative Fishery Research Unit College of Fisheries, University of Washington Seattle. WA 98195 A CONTRIBUTION TO THE BIOLOGY OF THE PUFFERS SPHOEROIDES TESTUDINEUS AND SPHOEROIDES SPENCl.ERI FROM BISCAYNE bay, FLORIDA The general biology of the checkered puffer, Sphoeroides testiidineus, and bandtail puffer, S. spengleri, is not as well known as that of the northern puffer, S. maculatus. For example, Chesapeake Bay populations ofthe northern puff- er have been examined for length-weight rela- tionships by Isaacson (1963) and Laroche and Davis (1973), for age, growth, and reproductive biology by Laroche and Davis (1973), and for fecundity by Merriner and Laroche (1977). None of this information is available on the checkered or bandtail puffer. Checkered and bandtail puffers have greater geographic ranges and are more southern in dis- tribution than the northern puffer. The checkered puffer is abundant from the Atlantic coast of southern Florida, throughout the Caribbean Is- lands, Campeche Bay, and along the coasts of Central and South America to Santos, Brazil (Shipp 1974). The bandtail puffer is common in the Caribbean Sea and along the coasts of peninsular Florida, the Bahamas, and Bermuda (Shipp 1974). I report here on growth, reproduction, and the pharyngeal dentition of these two species gathered during a study of their feeding biology (Targett 1978). The sampling habitat was a shallow seagrass bed along the southwestern shore of Virginia Key in northern Biscayne Bay, Fla. Turtle grass, Thalassia testudmum , was the dominant seagrass with small amounts of shoal grass, Halodule wnghtii, and manatee grass, Syringodium filiforme, also present. Monthly collections from September 1973 to December 1974 yielded 414 checkered puffers (15-215 mm SL; 569^ females) and 548 bandtail puffers (16-133 mm SL; 49^;^ females). Seawater temperatures ranged from 16.5° to 32.0°C and salinities from 30.5 to 38.5%o. Standard length-weight relationships (Figures 1,2) were calculated using functional regressions (Ricker 1973). Checkered puffers grow to a larger size and are heavier than bandtail puffers at a given length. Comparisons of these results with those for northern puffers from Chesapeake Bay (Isaacson 1963; Laroche and Davis 1973) was made possible by the conversion of total length to standard length using the factor: caudal fin length = 20. 2"^^, SL (Shipp 1974). Northern puffers grow 292 FISHERY Bl'LLETIN VOL 1 — I — I — \ — I — I — I — n — I— I- 20 40 60 80 100 120 140 160 180 200 220 STANDARD LENGTH ( mm ) Figure l— Standard length-weight relationship for 250 check- ered puffers from Biscayne Bay, Fla. Functional regression parameters derived by least squares fit to log transformed data, where variance about regression was S^,^ = 0.0014. to a greater maximum size than either checkered or bandtail puffers and are approximately the same weight at a given length as checkered puff- ers. Checkered puffers decreased in alDundance in June and July due to a drop in numbers of 120-169 mm SL fish (Figure 3). (Some individuals may have left the seagrass bed as early as April and May, since a greater effort was needed to catch checkered puffers at that time, ) Males and females decreased equally in abundance. The group leav- ing the seagrass bed may have been going elsewhere to spawn since their departure corre- sponded with the time of capture of ripe individu- als. Some ripe checkered puffers were captured in April and May; and by August, September, and the beginning of October the few adults caught 60 80 STANDARD LENGTH ( n FIGTRE 2 —Standard length-weight relationship for 250 bandtail puffers from Biscayne Bay, Fla Functional regression parameters derived by least squares fit to log transformed data, where variance about regression was S, ,^ = 0.0018. 20 r Hn n n n n n r-1 n ,-, CL_ n n n „ n n- n n n n n II n nn nnn nnnnn .nn n n n n .;. , , SIZE CLASS (n Figure 3.— Monthly standard length-frequency distributions for checkered puffers from Biscayne Bay, Fla , during 1974 293 were all ripe. Furthermore, Christensen (1965) found evidence that checkered puffers from Jupi- ter Inlet, Fla., spawned in low salinity waters dur- ing the fall. He found young fish (s£lO mm SL) from early November through December in waters having salinities generally <20%ii. He also ob- served that young and juveniles were abundant in the upper reaches of the Loxahatchee River ( which flows into Jupiter Inlet ) durmg winter and spring, rarely being found elsewhere. Thus, the checkered puffers leaving the seagrass bed in the present study may have been going to spawn in lower salinity waters found along portions of western Biscayne Bay or in the Miami River. This would explain why no checkered puffers <25 mm SL were captured, except for six in October. Most young likely remain in brackish water areas and move into higher salinity habitats only at larger sizes the following year. The 80-119 mm SL group appearing in August probably composed the 1-yr- old fish moving into the seagrass bed. The checkered puffer spawning season, begin- ning in the spring and concentrated during sum- mer and early fall in Biscayne Bay, occurs slightly later than the spring and summer spawning of the southern puffer, S. nephelus, at Cedar Key, Fla. (Reid 1954). The northern puffer in Chesapeake Bay has been reported to spawn during May by Hildebrand and Schroeder ( 19281 and during late May, June, and July by Laroche and Davis (1973). Fecundity analysis, using the gravimetric technique, was done on nine checkered puffer females ranging from 127 to 178 mm SL (99-256 g). Only yolky eggs, with nuclei obscured, were counted. Regression analyses of fecundity- standard length and fecundity-body weight were done using functional regressions (Ricker 1973). Total fecundity increased exponentially as a func- tion of body length (Figure 4) and linearly as a function of body weight (Fecundity = 1,431.81 [Body wt in grams] - 45,704.97; r = 0.96), Over the size range examined, relative fecundity aver- aged 1,146 eggs/g body wt. These fecundity values are greater than those found by Merriner and Laroche ( 1977) for northern puffers in Chesapeake Bay. Of the six checkered puffers <25 mm SL, two (15 and 23 mm SL) were males and the sex of the rest ( 17, 17, 18, and 21 mm SL) was undetermm- able. Thus, it was not possible to estimate the body size at which eggs become discernible. The age structure of the checkered puffer popu- lation can be inferred from the monthly length- frequency distributions (Figure 3). The 80-119 V: 0O48 X r: 88 50-1 1 1 r 120 130 140 150 180 STANDARD LENGTH (mm) Flia'RK 4— Tola) fecundity-standard length relationship for nine checkered puffers from Biscayne Bay, Fla. Functional re- gression parameters derived by least squares fit to log trans- formed data, where variance about regression wasSy.,^-0.(X)78. mm SL group appearing in August is likely 1-yr- old fish which grow to 1 20- 1 89 mm SL by the end of their second year. A comparison of the growth of checkered puffers in this population with results from the work of Laroche and Davis (1973) on northern puffers from Chesapeake Bay shows that the checkered puffers reach a smaller size at the end of each year of life and are shorter lived than the northern puffers. Eggs became discernible, by microscope, in bandtail puffers at 25-30 mm SL. Spawning sea- son, however, was not easily determined. No ripe or nearly ripe bandtail puffers were caught despite the fact that this species was abundant through- out the year and the full size range (to approxi- mately 160 mmTL(Shipp 1974)) was captured. At least one fish <30 mm SL was collected every month except September, November, and De- cember, although most were captured during March through June. This implies that bandtail puffers have a long spawning season, concentrated in the late fall and early winter, and spawn elsewhere with the young moving into the sea- grass bed shortly after hatching. Both checkered and bandtail puffers feed mainly on crabs, bivalves, and gastropods (Targett 1978). They use their beaklike jaws (paired pre- maxillary and dentary bones) to break the shelled prey. Two specimens of both species were cleared and stained, revealing that they have similar 294 pharyngeal dentition. Three pairs of dorsal pharyngeal tooth plates are present, associated with the pharyngobranchial elements of branchial arches I, II, and III, with one tooth plate of each pair being located on either side of the dorsal mid- line. Each tooth plate is slightly curved with a posteriorly directed dentigerous surface. In the 126- and 137-mm SL checkered puffers, the four tooth plates in the anterior two pairs were each 4 mm long and those in the posterior pair were each 3 mm long. In the 108- and 118-mm SL bandtail puffers, the four tooth plates in the anterior two pairs were each 3 mm long and those in the poste- rior pair were each 2 mm long. The dorsal pharyngeal tooth plates of both puffer species bear upon the pair of ventrally located, and nonden- tigerous, fifth ceratobranchial (lower pharyngeal) bones. The pharyngeal tooth apparatuses likely function to pull flesh from and to further grind and break crab and mollusc shells. The smooth puffer, Lagocephalus laevigatus, also has strong beaklike jaw teeth but has dentigerous tooth plates as- sociated with the pharyngobranchial elements of only the II and III branchial arches (Tyler 1962). In general, fishes in the Order Plectognathi have very strong jaw teeth and comparatively weak pharyngeal dentition (Al-Hussaini 1947). Acknowledgments MERRINER. J. v., AND J, L. L,-\HOCHE 1977 Fecundity of the northern puffer, Sphoeroides maculatus. from Chesapeake Bay. Chesapeake Sei. 18;81-83. REID. G K, JR. 1954, An ecological study of the Gulf of Mexico fishes, in the vicinity of Cedar Key, Florida. Bull. Mar. Sci. Gulf Caribb, 4:1-94, RICKER. W. E. 1973, Linear regressions in fishery research J Fish. Res. Board Can, 30:409-434. SHIPP. R, L. 1974. The pufferfishes (Tetraodontidael of the Atlantic Ocean, Publ Gulf Coast Res. Lab, Mus, 4, 163 p, T.ARGErr, T, E, 1978. Food resource partitioning by the pufferfishes Sphoeroides spenglen and S. testudineus from Biscayne Bay, Florida. Mar, Biol, iBerl.) 49:83-91, TYLER, J. C 1962, The general osteology of representative fishes of the Order Plectognathi, Ph.D. Thesis, Stanford Univ., Palo Alto, Calif. 388 p. Timothy E, Targett Department of Zoology University of Maine Orono. ME 04473 CORRELATES OF MATURITY IN THE COMMON DOLPHIN, DELPHl''0.10, Kendall's rank corre- lation test). Both sexually mature and immature females occur with 7-14 dentine layers (Figure 2). Testes weights are so variable in the range of 7-12 dentine layers that they cannot be estimated (Fig- ure 3), although significantly correlated over the entire range of data (PsO.OOl, Kendall's rank cor- relation). Body length is a poor indicator of sexual de- velopment. Over body lengths 175-190 cm, testes apparently undergo a transitional stage of growth. Gonad weight cannot be accurately estimated from body length over this range (Figure 4) al- though the two are significantly correlated over the entire range of data (PsO.OOl, Kendall's rank correlation). Body length and ovarian scarring are poorly correlated (P>0. 10, Kendall's rank correla- tion). Body lengths 165-182 cm include both sex- ually mature and immature females (Figure 5). 1 1 1 1 — ^T- } T ~^ 1 1 1 1 14 _ — _ • - 12 _ • — _ • - If '0 _ N = 51 • — 4 - • • - 1 6 [ • • • • - < 2 — • • • • • « • -• *- • 1 1 • • 1 1 1 • • 1 1 • 1 _L • 1 * 1 1 1 1 DENTINE LAYERS Figure 2. — Ovarian corpora in relation to dentine layers in Delphinus delphis. The stippled region indicates the range of dentine layers over which sexually mature animals are indistin- guishable from immature. 1000 800 T — I — I — I — I — I — I — I — I — I — I — I — I — I — r- I ' I ' I II * I • • t • # DENTINE LAYERS FIGURE 3.— Testis weight in relation to dentine layers in Del- phinus delphis. The stippled region indicates the range of den- tine layers over which testes of mature and immature weights overlap. The FI is significantly correlated with testes weights (P=£0.001, Kendall's rank correlation) although data are missing in a narrow range (Fig- ure 6). However, inactive ovaries occur in a wide 297 lOOS 800 '^ 200 9 100 50 - 1 1 1 1 1 - N-36 • - • •• • • _ .* • • • • • _ - I 1 1 1 1 TOTAL BODY LENGTH (cmj FIGURE 4.— Testes weights in relation to body length. The stip- pled area indicates the region of overlap for mature and imma- ture testes weights. 1 ' r -T-: M, 140 160 • * • * 80DY LENGTH Figures. — Ovarian corpora related to body length mDelphinus delphis. The range of body lengths in which sexually mature and immature animals cannot be distinguished is indicated by the strippled area range of FI scores (Figure 7) and there is no sig- nificant relationship between the number of ovar- ian scars and the FI (P >0.10, Kendall's rank cor- relation). Robustness is here defined as the body length in centimeters divided by body weight in kilograms. Regardless of body length, only the most robust individuals are sexually mature. Sexual maturity occurs when the male's length/weight ratio de- 298 FLIPPER INDEX Figure 6. — Development of testes related to epiphyseal de- velopment of the pectoral appendages in Delphinus delphts as indicated by the Flipper Index, The best interpretation of the present data is that two linear phases are separated by a stage of rapid change. T ' r i ' — I — ' — r Figure 7. — Ovarian corpora related to pectoral epiphyseal de- velopment (Flipper Index) \n Delph in usdelphis. The shaded area indicates the range in Flipper Index over which sexually mature and immature animals overlap. clines to about 2.6 (Figure 8). Mature females had length/weight ratios lower than about 3.0 (Figure 9). Of the 24 females with ovarian scars in this study, 16 were pregnant. Assuming the weight of the amniotic sack is nearly equal to that of the fetus, twice the weight of the fetus was subtracted from the gross weight of the mother, leaving the weight of the nonpregnant female for calculations of robustness. The robustness of the pregnant females is not separable from the sexually mature nonpregnant females. • TESTES WEIGHT - lOOq N - It A TESTES WEIGHT >350q. N - 6 Figure 8— The body length/weight ratio as related to body length in male Delphinus delphis. Individuals with combined testes weights of 350 g are considered to be undergoing sper- matogenesis. The shading designates the weightylength ratio in which males apparently are sexually mature. 70 • • 1 1 1 • "" I I 1 • • • • IMMATURE, N"?9 i • • E « A MATURE N 7A • ^ 50 • • - t • • i " - • ••• ~ I • • • • o • i • • - -■ JO "5r * 4ft X 20 - 1 1 1 L_ 1 1 1 - BODY LENCTI FIGURE 9, — Relationship of the body length/weight ratio to body length in female Delphinus delphis. Triangles represent indi- viduals with at least one ovarian corpus. The shaded area de- notes length/weight ratios in which sexually mature dolphins predominate. Discussion The data indicate that sexual development is better correlated with parameters which indicate the individual's proximity to physical maturity than with fixed morphometric values. A large in- crease in combined testes weight from <80 g to almost 400 g corresponds with rapid skeletal growth in the individual dolphin (Figure 6). Con- sequently, the FI is better correlated with sexual maturity in males than dentine layers or body length. Robustness is also highly correlated with sexual development in males but the sample size is small. For unknown reasons, ovulation is better corre- lated with the length/weight ratio than with body length, dentine layers, or flipper bone develop- ment. Similarly, in studies of humans, it was found that girls who attained early menarche also had greater weight for height than their chronological peers who attained maturity at a later time (Simons and Greulich 1943). Data from S. attenuata (Perrin et al. 1976) also show ovarian corpora to be poorly correlated with age and length. Induced ovulation is a distinct possibility for D. delphis. Harrison and Ridgway (1971) concluded that ovulation in Tursiopa truncatus is induced but the mechanism is unknown. The present data imply that someD. delphis females never ovulate, supporting the findings of Harrison et al. ( 1972). Oliver's' examination of Delphinus from the eastern tropical Pacific showed that the smallest testes with spermatogenesis weighed 140 g. For the present study, specimens with combined testes weights >350 g were collected in March, April, July, September, October, November, and De- cember. The large testes weights throughout the year indicate that there is no seasonal rut, sup- porting the findings of Harrison et al. ( 1969). Gaps in the data occur immediately prior to maleD. delphis sexual maturity: FI scores 85-105 (Figure 6), body lengths 158-177 cm (Figure 4), 4-8 dentine layers (Figure 2). These gaps appear to be the prepuberty ranges for those indicators. Be- havior patterns may account for the absence of data in these regions. Young males of Physeter catodon (Ohsumi 1971) and Tursiops truncatus (Evans and Bastian 1969) frequently herd sepa- rately from the rest of the population. Alterna- tively, these animals may have a greater capacity to escape nets. Female specimens also are lacking in the length, age, and FI ranges just prior to the demonstration of ovarian scars. Preadolescent females, like the males, may easily escape nets, or have a social structure separate from the main herd. Acknowledgments Mary F. P. Rieger and Linda J. Harrington pro- vided assistance with the statistics and ovary examination, respectively. G. A. Bartholomew, F. G. Wood, W. E. Evans, W. F. Perrin, and J. C. Quast offered helpful suggestions on the manu- script. 'C. W. Oliver, Inter-American Tropical Tuna Commission, La JoUa, CA 92037. Unpubl. data, 299 Literature Cited EVANS, W. E . AND J, BASTIAN. 1969. Marine mammal communications; social and ecolog- ical factors. In H. T. Andersen (editor), Biology of marine mammals, p. 425-475. Academic Press, N.Y. Harrison, R. J., R. C. Boice. and R. L. Brownell. Jr 1969 Reproduction in wild and captive dolphins. Nature (Lond.) 222:1143-1147. Harrison, R, J., R, L. Brownell, Jr , and R, C. Boice 1972. Reproduction and gonadal appearances in some odontocetes. In R. J. Harrison (editorl. Functional anatomy of marine mammals, Vol 1, p 361-429 Academic Press, N.Y. Harrison, R. J., and S. H. Ridgway. 1971. Gonadal activity in some bottlenose dolphins iTur- Slops truncatus). J. Zool. (Lond. I 165:355-366. Kleinenberg. S. E., and G. A. Klevezal 1962. Towards a method for determining the age of toothed whales. \In Russ.l Dokl. Akad. Nauk. SSR Inst. Morfol. Zhivotn. OHSUMI, S. 1971. Some investigations on the school structure of sperm whale. Sci Rep Whales Res. Inst. Tokyo 23:1-25. PERRIN. W. F. 1975. Variation of spotted and spinner porpoise (genus Stenella) in the eastern Pacific and Hawaii. Bull. Scripps Inst. Oceanogr. Univ. Calif. 21, 206 p PERRIN. W. F., J. M. COE. AND J. R. ZWEIFEL 1976. Growth and reproduction of the spotted porpoise, Stenella atteituata, in the offshore eastern tropical Pac- ific. Fish. Bull., U.S. 74:229-269. SIMMONS. K., AND W. W. GREULICH 1943. Menarcheal age and the height, weight, and skeletal age of girls age 7 to 17 years. J. Pediatr. 22:518-548. SINCLAIR, D. 1973. Human growth after birth. Oxford Univ. Press. N.Y., 212p. SOKAL, R. R.. AND F. J. ROHLF, 1 969. Biometry: The principles and practice of statistics in biological research. W H. Freeman and Co.. San Franc. 776 p. Clifford a. Hui Biomedtal Branch Naval Ocean Systems Center San Diego. CA 92152 LARVAL DEVELOPMENT OF GOBIESO\ RHESSODON (GOBIESOCIDAE) WITH NOTES ON THE LARVA OF RIMICOLA MVSCARVM Seven species of clingfishes of the genera Gohiesox and Rimicola occupy the rocky inter- and subtidal areas along the California coast. Extreme mod- ification of the pelvic fins into a suction disc ena- bles them to cling to rock and algal substrates. Although all clingfish species are listed as being uncommon to rare in California by Miller and Lea (1972). clingfish larvae are collected on a regular basis (although in low numbers) by monitoring programs dealing with fish larvae (Brewer,' McGowen,^ and White^). Of the seven species re- corded in southern California, adults of only two, G. rhessodon and R. nuiscariim, are usually en- countered (pers. obs.). Knowledge of larval stages of eastern Pacific (especially Californian) fishes is largely limited to pelagic species of those coastal species with pro- tracted pelagic larval periods (Ahlstrom 1965; Moser et al. 1977). Larvae of many nearshore, coastal fishes are undescribed. Recent concern over the affects of harbor development and ther- mal discharge and entrainment from power plants on fish populations has intensified the need for proper identification of fish eggs and larvae. The principal systematic work to date on the adults of eastern Pacific clingfishes was carried out by Briggs (1955). No previous works on the larvae of eastern Pacific clingfishes have been car- ried out, although the eggs and larvae of an Atlan- tic clingfish, G. strumosus, are well known (Run- yan 1961; Dovel 196.3). Descriptions of a larval series of G. r-hessodon and early larvae of R. muscarum are presented here as taxonomic aids to larval fish investigators working in the California coastal region. Methods and Materials Eggs and adults of G. rhessndnn and R. inus- cariini were collected in June 1977 from the inter- tidal zone at low tide at Catalina Harbor and Little Harbor, Santa Catalina Island, Calif. Adults with their eggs were transported to the Catalina Marine Science Center (CMSC) operated by the University of Southern California and maintained in tanks with running seawater. The failure of hatched larvae to feed (probably due to lack of suitable food) precluded culturing past 2 days (4.0 mm). Additional specimens of G. rhessodon utilized in the series were obtained by vertical plankton tow under a night-light at the CMSC dock in Big Fisherman's Cove (4.7 mm) in June 1977; by horizontal tow in King Harbor, Redondo 'Gary D. Brewer, Institute for Marine and Coastal Studies, University of Southern California, Los Angeles, CA 90007. Pers. commun. June 1977. ^Gerald E. McGowen, Southern California Edison (Occidental Collegel, Redondo Beach, Calif Pers. commun. June 1977. ^Wayne S. White, U.S. Fish and Wildlife Service, Laguna Niguel, Calif. Pers. commun. August 1977. 300 FISHERY BULLETIN VOL Beach, Calif. (7.5 mm), in 1977; by otter trawl in Marina del Ray, Calif. (12.0 mm), in June 1977: and from the larval fish collection of the Harbors Environmental Projects (University of Southern California) taken by horizontal plankton tows in Los Angeles Harbor (specimens collected in 1972-73). A total of 32 larvae from 2.6 to 7.5 mm of G. rhessodon were examined for larval charac- teristics. An additional 311 larvae ofG. rhessodon (2.9-7.5 mm) from King Harbor were checked spe- cifically for the presence of melanophores on the head. Larvae were examined and drawn using a Wild'* stereomicroscope fitted with a camera lucida. Standard length (SL) was measured from the tip of the snout to the tip of the notochord until completion of notochord flexion and then to the posterior margin of the hypural plate. Results and Discussion Gohieiox rhesiiidiiti The most distinctive character of G. rhessodon larvae was the presence of 8-17 (mean 12) stellate melanophores, which ran laterally in two or three rows from the pectoral fin region to just posterior to the anus (Table 1, Figures 1-3). The dorsum of the gut was also heavily pigmented with stellate melanophores (not included in the lateral melanophore counts). The gut pigmentation often obscured the well-developed swim bladder. Myo- mere counts ranged from 24 to 29 (mean 27) but were difficult to count, especially in early stages. All specimens up to 6.9 mm had four to seven ■•Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. Table l. — Summary of larval measurements and adult counts for Gobiesox rhessodon andRtrnicola muscarum (Miller and Lea 1972 and present study). Gobiesox Rimicola Item rhessodon muscarum Larvae No. lateral melanophiores 8-17 (X = 12) 40-50 in in 2-3 rows 4 rows Myomere count 24-29 (X = 27) (') No ventral tail melanophores 4-7 Absent Size (mm) at onset ot pelvic fin development S.S 9 Adults No visible dorsal tin rays 10-12 6-8 No visible anal tin rays 9-10 6-8 No pectoral tin rays 19-21 14-17 No vertebrae '28- 29 ^35-36 regularly spaced melanophores along the ventral portion of the tail region. The length of the gut averaged approximately 35*7^ of body length in all specimens examined. Head length ranged from 19 to 25'7f SL in most specimens <6.5 mm. Individu- als 5^6.5 mm had a much larger head of about 33'7f of SL. All specimens had a stellate melanophore at the base of each pectoral fin which was covered by the opercular flap in later stages ( >6.9 mm). The larvae from Catalina and Los Angeles Harbor pos- sessed from zero to four spots on the dorsal portion of the head. Forty-two percent (mean 24, range 2.6-6.9 mm) of the larvae had head pigmentation in the form of spots. Of the larvae examined from King Harbor, 79^f (mean 311) lacked this head pigmentation. The larvae with and without head spots were very similar in every other respect. The larvae of G. rhessodon hatched at about 4.0 mm (three specimens ranged from 3.9 to 4.1 mm) from attached, monolayered eggs laid under rocks and cobble in the intertidal zone at Catalina Is- land. Nest guarding adults have been found from spring to early summer by Lavenberg.^ The rela- tively advanced larvae possessed well-developed jaws and pectoral fins at hatching and a laterally bilobed yolk, which was absorbed within the first 24 h. The gut had two or three constrictions giving it the appearance of being looped. The constric- tions were characteristic of the larvae up to 6.9 mm. Notochord flexion occurred between 5.5 and 6.9 mm, and caudal fin rays started to develop just prior to flexion. Dorsal and anal fin ray develop- ment began around 6.2 mm and the fins were de- veloped sufficiently for positive identification at about 6.9 mm. The development of the pelvic fins began at 5.5 mm and the characteristic suction disc was formed at about 7.0 mm. Transformation and settling probably occur between 8 and 12 mm as evidenced by an 8-mm planktonic specimen from King Harbor that possessed juvenile pigmen- tation (McGowen see footnote 2) and the 12-mm juvenile (Figure 3) which was collected by benthic otter trawl. This latter specimen exhibited the ability to cling to surfaces after capture. Larvae of G. rhessodon appear to be the most common Gobiesox encountered in several near- shore plankton sampling programs in southern California (Brewer see footnote 1; McGowen see footnote 2; White see footnote 3). This is to be expected in that previous species lists of adult/ 'Lateral melanophores obscurred myomeres so that accurate counts could not be taken ^Counts from Los Angeles County Museum specimen X-rays — G rhessodon (LACM1998), (ourspecimens, R rrruscarum (LACMW70-16). six specimens ^Robert J. Lavenberg. Curator of Fishes. Los Angeles County Museum of Natural History, Los Angeles, CA 90007. Pers. com- mun. June 1977. 301 4 . 7 WW 5.5 mm 6.2 wm Figure 1. — Developmental stages ofGobiesox rhessodon . The 3,9-mm larva was reared in the laboratory i <24 hi. The remainder are from plankton collections. juvenile fishes in southern California coastal areas have included G. rhessodon exclusively (Horn and Allen 1976). RiniiLoU. I numiirnm postanal myomere, and the absence of pigmenta- tion on the ventral tail region (Table 1). Yolk-sac larvae do not have head pigment. Adult counts are also markedly different from G. rhessodon (Table 1). Yolk-sac larvae of R. niuscarum (Figure 4), shortly after hatching, can be distinguished from G. rhessodon larvae at this stage by the greater number of lateral, stellate melanophores (40-50) in four rows that continue to the sixth or seventh Comparison Three species oiGobiesox, in addition to G. rhes- sodon. have been reported in southern California: G. macndricus, G. paplllifer, and G. eugrammiis. 302 Figure 2. — Pelagic larvae of Gobiesox rhessodon . 6 . 9 mm 7.5 nun Figure 3— Late pelagic larva (upper) and benthic juvenile (lower) of Gobiesox rhessodon . &,^X J2.0 mm The larval stages of G. maeandricus have recently been described by Marliave ( 1976). Based on Mar- liave's description and data from Richardson,^ G. maeandricus larvae differ from G. rhessodon mainly in that G. maeandricus lack lateral melanophores and possess more myomeres (31-33). In addition, adults of G. maeandricus are rare south of Point Conception, Calif. (Miller and Lea 1972). Gobiesox papillifer and G. eugrammus are also rare in southern California. Gobiesox papil- lifer has been reported only once in southern California, and G. eugrammus only ranges as far north as San Diego County (Miller and Lea 1972). The larvae of these two species of Gobiesox have ^Sally L. Richardson, School of Oceanography, Oregon State University. Corvallis, OR 97331. Pers. commun. May 1978. not been described, however, it is unlikely that any of these forms were among the specimens examined considering the distributions of the adults. The Atlantic species of Gobiesox, G. strumosus, studied by Runyan (1961) and Dovel (1963) was similar in appearance to G. rhessodon , but does differ in that the Atlantic species had 10-15 saddle melanophores (as opposed to lateral) and dis- played no ventral midline pigment in the early stages (<3.9 mm). Later larvae of G. strumosus also appeared to be more heavily pigmented on the trunk portion of the body (4.73-8.78 mm). The presence or absence of head pigmentation has been used by some investigators to separate Gobiesox larvae collected in southern California into two types. This character is variable in G. Figure 4. — Yolk stage larva ofRinncola mus- carum . 4 . mm 303 rhessodon and, therefore, is not useful in distin- guishing it from other species. Acknowledgments For their advice and instruction, I thank Robert J. Lavenberg and H. Geoffrey Moser. Gary D. Brewer and Gerald E. McGowen gave advice and field and laboratoiy assistance, and provided speci- mens. Brian White, Marty Meisler, Marianne Ninos, Layne Nordgren, A. Kubo. Delaine Wink- ler, Sarah Swank, Scott Ralston, and Tina Beh- rents assisted in the field collection of eggs, larvae, and adult clingfishes. Michael H. Horn, Robert J. Lavenberg, H. Geoffrey Moser, and Sally L. Richardson greatly enhanced the manuscript through their critical reviews. Literature Cited AHLSTROM. E. H. 1965. Kinds and abundance of fishes in the California Cur- rent region based on egg and larval surveys. Calif Coop. Oceanic Fish. Invest. Rep. 10:31-52. BRIGGS. J. C. 1955. A monograph of the clingfishes (order Xenop- terygiii. Stanford Ichthyol Bull. 6:1-224. DOVEL, W. L. 1963. Larval development of clingfish, Gobiesox strumosus, 4.0 to 12.0 millimeters in total length. Chesapeake Sci. 4:161-166. HORN, M. H., .'^ND L. G. ALLEN. 1976. Numbers of species and faunal resemblance of marine fishes in California bays and estuaries. Bull. South. Calif Acad. Sci. 75:159-170, MARLIAVE. J. B. 1976 The behavioral transformation from the planktonic lar\'al stage of some marine fishes reared in the labor- atory. Ph.D. Thesis, Univ. British Columbia, Van- couver. 231 p. Miller, D. J., and R. N. Lea. 1972. Guide to the coastal marine fishes of California Calif Dep. Fish. Game, Fish Bull. 157, 235 p. Moser, H. G., E, H. Ahlstrom, and E. M. Sandknop. 1977. Guide to the identification of scorpionfish larvae I family Scorpaenidae) in the eastern Pacific with com- parative notes on species oiSebastes andHeltcolenus from other oceans U..S. Dep. Commer., NOAA Tech. Rep NMFS Circ, 402, 71 p, RUNYAN, S. 1961. Early development of the clingfish, Gobiesox strumosus Cope. Chesapeake Sci. 2:113-141. SPRING AND SUMMER FOODS OF WALLEYE POLLOCK, THERAGRA CHALCOGRAMMA, IN THE EASTERN BERING SEA The walleye (Alaska) pollock, Theragra chalco- grainma (Pallas 1811 ), is the most abundant com- mercial fish species in the eastern Bering Sea (Pereyra et al.M and plays an important role in ecosystem trophodynamics of the region. To obtain better knowledge of the role of the pollock as a predator, we have studied the stomach contents of pollock from the eastern Bering Sea collected on U.S. research vessels in the summer of 1974 and on Soviet and Japanese fishing vessels in the spring of 1977. Results from this study contribute to our under- standing of feeding habits; information on sea- sonal and size-dependent changes in feeding be- havior are used to model interactions between species (trophodynamics), and to predict the influence of commercial fisheries on the abun- dance of populations in the eastern Bering Sea (Laevastu and Favorite-'*). Methods Pollock stomachs were collected by U.S. fisheries observers, on an opportunistic basis, aboard Soviet and Japanese motherships in the eastern Bering Sea. Samples were collected in the region of the continental shelf break in April and May 1977 (Figure 1, Table 1). The stomachs were removed, tied in cheesecloth, and preserved in di- lute Formalin'' (ca. 5Vf ) and sent to the Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, Wash., for analysis. Identifiable matter was separated by major taxa. Wet weight for each taxa was deter- mined after blotting with paper towels. Uniden- LARRY G. ALLEN Department of Biological Sciences University of Southern California Los Angeles. CA 90007 'Pereyra, W. T., J. E Reeves, and R. G. Bakka- la. 1976 Demersal fish and shellfish resources of the eastern BeringSeain the baseline year 1975. Unpubl. manuscr, vol. 1, 619 p. Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. ^Laevastu. T. and F. Favorite. 1976. Evaluation of .stand- ing stocks of marine resources in the eastern Bering Sea. Un- publ. manuscr.. .35 p. Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd. E., Seattle. WA 98112. ^Laevastu, T, and F Favorite. 1976. Dynamics of pollock and herring biomasses in the eastern Bering Sea. Unpubl. manuscr., 50 p. Northwest and Alaska Fisheries Center. Na- tional Marine Fisheries Service, NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. ''Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. 304 FISHERY Bl'LLETIN VOL 77. NO I.Ii)79. 180° 178° 176° 174° 172° 170° 168° 166° 164 162° 160° 158° 156° Figure l. — Location sites where walleye pollock stomach samples were collected in the eastern Bering Sea. Table l. — Summary of walleye pollock stomach samples col- lected in the eastern Bering Sea. No of Depth Average Sampling stomachs range (m) depth Vessel penod collected of bottom (m) Oregon (US) July 1974 352 71-132 99 Chiltubu Maru (Jpn) Apr 1977 180 124-210 194 Tiraspol (USS.R) Apr 1977 225 128-256 167 7enyo Maru #3 Apr -May (Jpn.) 1977 Total 92 849 110-165 132 tifiable matter was classed as "digested material" and also weighed. Percentage of food weight for each major food category, by fish-length group, was calculated as was the weight for each major food category per fish for each length group. Empty stomachs were not included in the analysis. Detailed length data from foreign fishing ves- sels were available only from the Japanese fishing vessel Tenyo Maru. These data were analyzed by 10-cm fork length classes. Fish lengths from the Japanese fishing vessel Chikuhu Maru and the Soviet fishing vessel Tiraspol were recorded only as greater or less than 35 cm (the approximate length at sexual maturity). This is also the size at which pollock become markedly cannibalistic (Takahashi and Yamaguchi 1972). Data from all three observer cruises were combined using these two major size categories to obtain sufficient sam- ple sizes for comparison with the data collected in 1974. Data collected in 1974 (RV Oregon) were examined by 5-cm length classes. The larger number of stomach samples collected during this cruise allowed a finer analysis of size-related changes in feeding habits. The methods used for processing samples from this cruise were approx- imately the same as for samples from the foreign vessels. Results An examination of stomach content weight by fish-length group provided evidence of related shifts in principal food categories in the diet of pollock (Figures 2, 3). In both spring 1977 and summer 1974, the percentage of copepods as food biomass tended to decrease with increasing size of pollock. The percentage offish in pollock stomachs tended to increase with the size of pollock. Euphausiids were important food components in most length classes in both sampling periods. Am- phipods, however, were only abundant in 305 lOOr FIGURE 2— Percent biomass of stomach contents by taxa per 5-cm length group of Bering Sea walleye pol- lock, summer 1974, CO <50 o III FISH SHRIMP DIGESTED MATTER EUPHflUSIIDS AMPHIPOOS COPEPODS 519 20-24 25-29 30-34 35-39 40-44 45-49 50' LENGTH (cm) 100 80-- 60 5 O 40 20- 0^ DIGESTED MATTER FISH EUPHAUSIIDS AMPHIPOOS COPEPODS 1 52'» 25-34 35-44 LENGTH (cm) Figure 3. — Percent biomass of stomach contents by taxa per 10-cm length group of Bering Sea walleye pollock, spring 1977 stomachs collected in summer 1974. and the per- centage of amiphods as food biomass tended to increase with increasing pollock size. Other food organisms that appeared in the diet are listed in Table 2. The analysis of stomach contents by weight-per- centage masks the behavioral aspects of pollock feeding due to size differences in food organisms. More information can be obtained from the data when analyzed as grams of food organisms per fish for each length class (Tables 3, 4). From this analysis it appears that larger pollock tended to exclude smaller food items from their diet. As the pollock grew larger they fed more on euphausiids, amphipods, and fish. 306 Table 2. — Proportion of taxa observed in walleye pollock stomachs in the eastern Bering Sea. Taxa Fish Copepods Euphausiids Amphipods Chaetognaths Cephalopods Mollusks Ostracods Larvaceans Annelids Shrimp Cumacean Nemerteans Mysids Crab Unidentified Digested Total Table 3. — Grams of food organisms per fish mot including fish with empty stomachsl in each size class, Tenyo Mam, spring 1977. Observei cruises. Oregon cruise. spring 1977 summe 1977 Weight (g) °o biomass Weight (g) °o biomass 277 07 28 53 223 21 25 94 349 81 36 02 44 60 518 210 02 21 62 81 70 949 2 15 22 235 63 27 38 47 05 17 77 2 07 30 03 — — 15 02 89 10 02 — _ _ 08 01 008 001 3 99 42 3 40 40 1291 1 33 979 1 14 — — 001 _ — — 092 11 — — 0,55 06 — _ 456 053 — — 1 64 19 114.09 11 75 235 83 27 40 971,06 100 00 860 58 100 00 Fork length ( :m) of pollock Item 15-24 25-34 35-44 •45 Grams copepods/fish 008 097 0,66 14 Grams euphausiids./fish 04 09 035 082 Grams tish,fish _ — 69 528 Grams total food,'fish 20 122 2 04 6 50 No of fish with food 6 28 14 19 Percentage of fish with empty stomachs 57 26 18 17 Data on the species composition offish in pollock stomachs were available from the summer cruise of 1974 [Oregon). Fish ingested were identified from the stomachs of 27 pollock ranging in fork length from 26 to 57 cm (mean = 40 cm). Of the fish ingested, 89^/f by weight and 39^f by number were Table 4. — Grams of food organisms per fish (not including fish with empty stomachs) in each size class, Oregon, summer 1974. Fork length (cm) of pollock Item •20 20-24 25-29 30-34 35-39 40-44 45-49 ■49 Grams copepods/ftsh 42 26 14 16 13 02 _ _ Grams amphipods/fish 04 04 27 33 080 2 90 2 20 1 23 Grams euphausiids/lish — — 20 038 030 25 31 031 Grams shrimp/(ish — — — — 001 — — 40 Grams fish/dsh — — 001 40 73 02 718 71 Grams total loodlish 62 70 1 27 1 97 291 4 57 1 1 24 4 00 No ot tish with food 20 14 94 64 70 22 18 22 Percentage of fishi witti empty stomactis 35 7 2 4 8 14 4 pollock. Other fishes identified included gadids, cottids, hexagrammids, and zoarcids. Pollock food composition in summer 1974 and spring 1977 can be compared although geographic locations of stomachs collected varied (Figure 4). Pollock were observed with more copepods as a percentage of food biomass in spring 1974 than in summer 1977. Amphipods were nearly absent from stomachs collected in spring 1974 but were an important food component in summer 1977. 100 D iscussion Previous studies on the food of the walleye pol- lock in the eastern Bering Sea indicated that in winter 1972, juvenile pollock fed mainly on euphausiids, while adult pollock fed on euphausiids, small pollock, and other fish (Mito 1974). In summer 1970, juvenile pollock fed on copepods and euphausiids, while adult pollock fed on euphausiids, small pollock, and other fish (Takahashi and Yamaguchi 1972). Our study in- dicates that in summer 1974 juveniles fed mostly on copepods, euphausiids, and amphipods, while adults fed on euphausiids, amphipods, and fish. In spring 1977, juvenile pollock fed mostly on copepods and euphausiids, while adult pollock fed on copepods, euphausiids, and fish. The results of these studies indicated that euphausiids are an important year-round food source of both juvenile and adult pollock. Fish appear to be an important year-round resource to adult pollock. The relative importance of other prey organisms in the diet of pollock seems to fluctuate between the studies. Adult pollock tend to obtain a greater percen- tage of their food biomass from larger prey or- ganisms than juvenile pollock, by ingesting more fish, euphausiids, and amphipods as they grow larger (Figures 2, 3). Additionally, larger pollock tend to exclude copepods from their diet (Tables 3, 4). These observations could result from an active process, based on preference or capture efficiency. < 5 o 50 FISH SHRIMP DIGESTED MATTER ANNELIDS CHAETOGNATHS EUPHAUSIIDS AMPHIPODS COPEPODS t35cm >35cm SUMMER 1974 t35cm >35cm SPRING 1977 FIGL'RE 4. — Percent biomass of stomach contents by taxa for adult and juvenile walleye pollock in summer 1974 and spring 1977 in the Bering Sea. or a passive process, resulting from spatial dis- tribution. Additional information is needed to understand the complexities of pollock feeding behavior, in- cluding: 1 ) seasonal variations in feeding behavior, 2) geographical variations, and 3) effects of alter- nate prey on cannibalism and grazing on other fish. This information would be useful in eco- system modelling to understand the natural com- petitive and predatory interactions between fish populations and the potential effects of heavy exploitation. Acknnw Icdgnients We thank the following persons at the North- west and Alaska Fisheries Center: Donald Day for collecting and making preliminary analysis of 1974 data, Robert French for arranging the collec- tion, and Beverly Vinter and Jay Clark for iden- 307 tifying the contents offish stomachs collected in 1977. Literature Cited MITO, K. 1974. Food relationships among benthic fish populations in the Bering Sea on the Theragra ckalcograninia fishing ground in October and November of 1972. (In Jpn.l M.S. Thesis, Hokkaido Univ.. Hokkaido, Jpn.. 135 P Takahashi, Y., and H. Yamaguchi. 1972. II — 2. Stock of the Alaska pollock in the Bering Sea. [In Jpn., Engl. summ. on p. 418-419, J In Svmposium on the Alaska pollock fishery and its resources, p. 389-.399. Bull, Jpn. Soc Sci. Fish. 38. KEVIN Bailey Jean Dunn Northwest and Alaska Fisheries Center National Marine Fisheries Sennce. NOAA 2725 Montlake Boulevard East, Seattle. WA 98112 FECUNDITY OF THE ATLANTIC MENHADEN, BREVOORTIA TY'RANNVS Although some work has been done to determine the time and place of spawning, age of spawning, and fecundity of Atlantic menhaden, Brevoortia tyrannus (Higham and Nicholson 1964), no at- tempt has been made to relate fecundity and age. In this study, I 1 ) examined the ovaries offish 1 to 5 yr old collected during autumn 1970, in the vicin- ity of Beaufort, N.C.; 2) estimated the number of ripening ova in sexually mature fish; 3) calculated the mean number of ova spawned by fish of each age; and 4) determined the reproductive potential and the net reproductive rates for the 1 954-63 year classes. Atlantic menahden, family Clupeidae, consti- tute a single biological population (Nicholson 1972, 1978; Dryfoos et al. 1973) inhabitating coastal waters from Florida to the Gulf of Maine. It is subjected to an intensive purse seine fishery from Florida to New England. Fish are landed daily at reduction plants and processed into meal, oil, and solubles. Fishing begins in Florida and North Carolina in late April, in New Jersey coast- al waters in early June, and in New England wa- ters in late June. Fishing usually ends in mid to late November, except in the vicinity of Beaufort where schools of migrating fish of all ages from northern areas provide an intensive fishery from November to late December or early January. Atlantic menhaden make extensive coastal movements and during the fishing season are stratified along the coast by age and size. In au- tumn most fish north of Virginia move southward and by January are concentrated in offshore wa- ters from Cape Hatteras to northern Florida. About mid-March they begin a northward move- ment and by mid-June are stratified in coastal waters by age and size, the younger and smaller farther south and the older and larger farther north (Nicholson 1971). South of Cape Hatteras and in Chesapeake Bay most fish are ages 1 and 2. Age-2 fish dominate in coastal waters off New Jersey, ages 3 and 4 in Long Island Sound, and age 4 and older north of Cape Cod. Although they may live to age 9, few older than age 6 are caught. Menhaden spawn in offshore coastal waters where the eggs hatch in 36 to 48 h (Reintjes 1962). Larvae, carried inshore by ocean currents, enter estuaries where they metamorphose to the adult form at about 35 mm total length. Although some spawning occurs in summer and early autumn in Long Island Sound and New England waters — the only areas where fish of spawning age are found during that time — most spawning occurs in the South Atlantic area from January to March and in the Middle Atlantic area from October to December and March to May. Although there ap- pears to be only one spawning cycle each year, evidence is uncertain as to whether Atlantic menhaden are fractional spawners (Higham and Nicholson 1964). As the population size decreased in the 1960's age structure also changed. Fish older than age 3 became extremely scarce, and most plants in the northern areas that were dependent on older fish closed. By 1969 few fish older than age 4 were landed, even in the North Carolina fall fishery, which traditionally had been dependent on older fish (Nicholson 1975). Collection and Preparation of Ovaries Ovaries were collected from 17 November to 29 December 1970 during the North Carolina fall fishery at the same time catches were being sam- pled routinely for age and size (June and Reintjes 1959). Sampling personnel measured and weighed the fish, removed scales for aging, and removed the ovaries. Only ripening ovaries fitting the 308 FISHERY BL'I.I.ETIN VOL 77. NO I.li)7() Stage III classification of Higham and Nicholson (1964) were retained. They were blotted on paper towels to remove excess moisture, weighed to the nearest 0.1 g, split longitudinally and turned in- side out, and placed in individual jars of Gilson's fluid modified by Simpson (Bagenal 1967). The jars were shaken to liberate all eggs. After the Gilson's fluid was poured off, along with most pul- verized ovarian tissue, the ova were washed and decanted in water several times and forced through a sieve to remove remaining fragments of ovarian tissue, spread on large trays covered with paper towels, and dried under incandescent lamps. Higham and Nicholson (1964) described four stages in the maturation of ovaries. Ovaries in the immature and intermediate stages contain only undeveloped ova; ovaries in the maturing and ripe stages contain developing as well as undeveloped ova. They concluded that only maturing ova ripened during each spawning period. Maturing ova were described as being opaque and yellow and between 0.35 and 0.78 mm in diameter. I fol- lowed this description to separate immature from maturing ova. I also measured fecundity by es- timating the number of maturing ova in both ovaries. Instead of counting ova in sample sections of the wet ovary, however, I counted ova in two replicate samples of the dried ova that had been separated from connective tissues. Before being weighed, eggs were allowed to equilibrate with air humidity. Each sample was weighed to the nearest 0.01 mg. If both ovaries weighed more than 12 g, two samples, each weighing 1/350 of the total weight, were taken. If the ovaries weighed 1 2 g or less, two replicate samples, each weighing 0.035 g, were taken, since fecundity would have been difficult to estimate in samples smaller than 0.035 g. Proportional sampling tended to minimize the counting error for a fixed amount of counting effort. Ova in each sample were counted under a stereoscope. The number of ova in both ovaries, A^, was estimated by multiplying the number of ova in the two samples, N,, by the ratio of total dry weight of eggs, W, , to dry weight of eggs in samples, W^ (N =A^sW,/W,). To minimize count- ing error between samples, a coefficient of varia- tion of 3.0^f or less was maintained. Preliminary calculations indicated that fecun- dity could be estimated with a precision of about 159c if 30 fish were selected randomly from each age-class. The ultimate number in each age-group was age 1, 21; age 2, 34; age 3, 33; age 4, 12; and age 5, 1 (Table 1). Table l. — Mean number of eggs (thousands! and mean ovary weight (grams), by age. for Atlantic menhaden sampled from the North Caro: Ima fall fishery, 1970. No Mean Mean of no of cv ovary C-V. Age fish eggs Range (%) wt Range (%) 1 21 115 8 26 5-250 7 47 179 4 0-43 5 54 2 34 177 4 39 2-368 8 50 30 1 5 0-62 5 55 3 33 302 8 127 7-458 3 30 50 9 21 1-96 9 34 4 12 308 6 142 7-514 36 48 5 22 0-74 8 36 5 1 568 4 - - 900 - — 'Coefficient of variation Fecundity The regressions of fecundity on ovary weight, F = 6,908(OW) - 17.937(OW)2, and fecundity on total fish weight, F = 293(TW) + O.'ZUiTW)^, were curvilinear, but fecundity on body weight only,F = 488(BW), was linear. Thefl^ values were 0.981, 0.675, and 0.916, respectively. Although the rela- tive merits of predicting fecundity from different variables are debatable (Bagenal 1967), these three models seem less useful than fecundity on age, which can be used to determine reproductive potential and calculate life table estimates, and fecundity on fish length, which can be used to predict the number of eggs spawned by different size classes. A statistical test failed to support the curvilinear relation implied by a plot of fecundity on age, perhaps because of the few fish in older age- groups. Of the two linear models tested for es- timating fecundity at age, I selected F = 92,592( Age ) as the better estimator (r^ = 0.879; SE slope = 3,440; SE regression = 89,110). It had tighter confidence limits and a higher r^ than the model F = a + bL. A logarithmic model (log F = a + bL) was selected to describe the curvilinear relation be- tween fecundity and length and was fitted to both my data and the data of Higham and Nicholson ( 1964) (Figure 1). Values predicted by this model fit observed values more closely over the entire range than those predicted by the nonlogarithmic model (F = fcjL -H 6.2L^). The difference in the slope coefficients of the logarithmic model fitted to the two sets of data was significant (P<0.001). Esti- mated fecundities were in reasonable agreement for fish up to 275 mm, but diverged for large fish. For 3.50 mm fish the model fitted to Higham and Nicholson data predicted about 1.75 as many ova as the model fitted to my data. Differences in fish ages or in the time of year fish were collected, or actual changes in fecundity might account for differences in estimates of ova 309 log f= 7 2227 + 0I76FL IHighom and Nicholson) V 200 250 275 300 FORK LENGTH (mm) Figure l— Regression of fecundity on fork length for Atlantic menhaden showing confidence limits on the mean at 95'? level ForlogF = 7.2227 + 0.0176^,^ = 38, SE regression = 0.3069; SE regression coefficient = 0.001 1, r^ = 0.726; for logf" = 8.6463 + 0.012QFZ,, Af = 101. SE regression = 0.3330, SE regression coefficient = 0.0007, r^ =0.871 for larger fish. Higham and Nicholson { 1964), e.g., had four fish with between 400,000 and 500,000 ova, four with between 500,000 and 600,000, and one with over 600,000, whereas from nearly three times as many fish I had only two with over 500,000 and six with between 400,000 and 500,000. I believe, however, that differences in counting techniques caused the differences in ova estimates. I used proportional sampling, whereas they did not. I separated the eggs from each other and from the connective tissue, dried and weighed the eggs, and then counted those in a sample. They counted the eggs in a sample from the wet ovary. Also, a certain amount of subjectivity is involved in distinguishing between maturing and non- maturing ova. Reproductive Potential and Net Reproductive Rate Since the sex ratio of Atlantic menhaden is about equal (Nicholson and Higham 1964), I was able to calculate the annual numbers of females of each age in the population, 1955-68, by dividing half of the number offish caught at each age by the exploitation rate for all ages (Schaaf and Huntsman 1972). When I collected my material in 1970, recording the maturing stage offish in catch samples had been discontinued, but Higham and Nicholson (1964) estimated that about 10'7f of age-1 fish, 909c of age 2, and lOf/i of age-3 or older fish examined during the North Carolina fall fishery in October-December from 1955 to 1959 had maturing ovaries. From these figures I calcu- lated the number of females of each age that would spawn each year and multiplied it by the mean number of ova spawned by fish of each age to estimate the number of eggs spawned each year (Table 2). The net reproductive rate, R„,oi' a population is defined as the sum of the products of the age- specific survival rate 4, and the age-specific natal- ity rate w,, of females (Odum 1971). A value of 1.0 for each generation would indicate that the popu- lation is stable and that there is a balance between births and deaths. In fish populations it is nearly impossible to obtain accurate counts or estimates of the number of offspring produced by each age- group. It is possible, however, to estimate the mean number of eggs spawned for fish of each age. If this variable is used for m, in the formula given by Odum and ifi/,"!, is called, /?o*. then the recip- rocal of /?„* should be a rough estimate of the survival rate of female eggs, providing the popula- tion is approximately stable. Although the Atlan- tic menhaden population declined after about 1960. 1 think in view of the imprecise estimates of other parameters, that it can be assumed stable for the purpose of estimating egg mortality. Ro* values were calculated for the 1954-63 year classes. I assumed a 0.65 survival rate up to age 1, which I divided into the estimated number offish that were age 1 (Schaaf and Huntsman 1972) for an estimate of the number of fish at the postlarval stage. Since the sex ratio is equal, this number divided into the estimated number offish surviv- ing to each age iSchaaf and Huntsman 1972) Table 2. — Estimated number of eggs (multiply by 10"! spawned by Atlantic menhaden, by year and age. Age in ^ears Year 1 2 3 4 5 6 7-9 Total 1955 83 377.6 723 2 1195 43.6 87 35 1.359 1 1956 69 7 443 9 1037 465 1 1188 31 1 10 7 1.243 1957 106 9 136.6 1667 127 2 144 9 197 60 708 1958 161 1 1313 510 62.8 429 28 8 30 480 9 1959 73.0 599.2 85.9 40 7 530 234 106 885 8 1960 329,8 205.3 457 9 142 59.4 21 1 68 1,222 3 1961 44 8 1,938 4 51 2 1046 127 43 1 5 2,1575 1962 57 7 270 2 877 6 85 85 124 34 1.391 3 1963 422 143 8 88 136 6 34 130 26 460 2 1964 38 4 95 3 34 1 199 210 50 1 4 215 1 1965 322 108 28 2 56 4 7 34 04 1825 1966 31 2 44 90 1 1 04 05 02 86 4 1967 20 5 101 1 11 8 1 5 — — — 134 9 1968 41 3 91 2 247 30 02 — — 160 4 310 yielded age-specific-survival fractions (/, ) for females of each year class. Ro* for each year class ranged from 7,100 to 25.800 (Table 3). The recip- rocal of these numbers, 0.000141 and 0.000039, respectively, indicate a survival rate ranging from 39 to 14 1 females, or 78 to 282 fish of both sexes, for each 1,000,000 eggs spawned. Any estimate based in turn on a series of rather imprecise and arbitrary estimates must be viewed with caution, and this one is no exception. Yet it is in line with current knowledge that the survival rate of pelagic fish eggs is extremely low. Table 3.— Net reproductive rates (/?„*! and their reciprocals (1/ffo*) for the 1954-63 year classes of Atlantic menhaden. Year Year class flo- l/flj- class fio- 1'flo- 1954 16.546 000050 1959 22,297 0000045 1955 7.109 000141 1960 10,120 000099 1956 25.932 000039 1961 14,073 000071 1957 11.850 000084 1962 11.024 000091 1958 21.856 000046 1963 11,181 000089 Literature Cited Bagenal, T. B. 1967. A short review offish fecundity. In S. D. Gerking (editor). The biological basis of freshwater fish production, p. 89-111, Blackwell Sci. Publ,. Oxf , Engl DRYFOOS. R, L., R. P, CHEEK, AND R. L. KROGER 1973, Preliminary analyses of Atlantic menhaden, Bre- voortia tyrannus, migrations, population structure, survi- val and exploitation rates, and availability as indicated from tag returns. Fish, Bull., U.S, 71;719-734. HIGHAM, J, R., AND W. R, NICHOLSON 1964. Sexual maturation and spawning of Atlantic menhaden. U,S, Fish Wildl. Serv., Fish, Bull. 63:255- 271. JUNE, F, C AND J, W. REINTJES 1959. Age and size composition of the menhaden catch along the Atlantic coast of the United States, 1952-55; with a brief review of the commercial fishery. U.S, Fish Wildl, Serv,, Spec. Sci, Rep, Fish, 317. 65 p. NICHOLSON. W. R. 1971. Coastal movements of Atlantic menhaden as in- ferred from changes in age and length distributions. Trans, Am, Fish, Soc, 100:708-716, 1972, Population structure and movements of Atlantic menhaden, Brevoortia tyrannus, as inferred from back- calculated length frequencies. Chesapeake Sci, 13:161- 174, 1975, Age and size composition of the Atlantic menhaden, Brevoortia tyrannus, purse seine catch, 1963-71, with a brief discussion of the fishery. US, Dep, Commer,, NOAA Tech. Rep, NMFS SSRF-684, 28 p. 1978, Movements and population structure of Atlantic menhaden indicated by tag returns. Estuaries 1:141- 150, NICHOLSON, W, R., AND J, R, HiGHAM, JR 1964. Age and size composition of the menhaden catch along the Atlantic coast ofthe United States, 1959, with a brief review ofthe commercial fishery, U,S. Fish Wildl, Serv,, Spec, Sci. Rep. Fish 478, 34 p, ODUM, E. P, 1971. Fundamentals of ecology, 3d ed W B, Saunders Co,, Phila,, Pa,, 574 p REINTJES. J, W, 1962. Development ofeggs and yolk-sac larvaeofyellowfin menhaden. U.S.Fish Wildl, Serv., Fish, Bull, 62:93-102, SCHAAF W. E., AND G. R, HUNTSMAN 1972. Effects of fishing on the Atlantic menhaden stock: 1955-1969. Trans, Am, Fish, Soc 101:290-297, CHARLES S, DIETRICH. jR Southeast Fisheries Center Beaufort Laboratory National Marine Fisheries Service, NOAA PO Box 570, Beaufort, NC 28516 ROLE OF LAND AND OCEAN MORTALITY IN YIELD OF MALE ALASKAN FUR SEAL, CALLORHINVS URSINVS The annua! commercial harvest of male fur seals has fluctuated widely and declined since the early 1950's, This has occurred despite a fairly stable harvesting regime and efforts to maintain the population near the level believed to be consistent with maximum sustainable productivity (Chap- man 1961, 1964, 1973). Variations in early natural mortality are mainly responsible for these changes in the harvest of males which occurs at ages 2-5 yr (mostly 3-4 yr). Kenyon et al. (1954) and Chapman' emphasized that natural mortal- ity between birth and age 3 yr is high and that most of it probably occurs during the first winter just after weaning. This report gives estimates of male survival from natural mortality of pups on land and from the first 20 mo of life at sea, a total interval of approximately 2 yr. The importance of pup num- bers and early survival rates in determining an- nual variations in abundance at age 3 yr is quan- tified also. Methods Data for survival estimates are in Table 1. The age composition of annual kills before 1950 cannot be determined accurately because an aging technique was not available until then (Scheffer 'Chapman, D. G, 1975, Methods of forecasting the kill of male seals on the Pribilof Islands. Background paper for the 19th Annual Meeting ofthe North Pacific Fur Seal Commission, 10 p- (Unpubl. rep.) FLSHERY BULLETIN VOL 77, NO 1, 1979. 311 Table l .—Estimated numbers of male pups (born, dead, and livmg at the time of migration! and age-specific commercial kill of males from the 1950-70 vear classes on St. Paul Island, Pribilof Islands. Alaska.' Number ot pups (thousands) Number killed at age Year class Born Dead Living 2 3 4 5 2-5 1950 225.5 26 7 199 855 40.656 15,365 332 57,208 1951 223.5 353 188 1.384 32,350 18,083 3,057 54.874 1952 219.0 20 4 199 1.735 30,773 31,410 675 64,553 1953 222.5 39 1 183 839 38,312 8,855 54 48.060 1954 225.0 48 1 177 2,918 23,473 5,599 554 32.544 1955 230.5 37 8 193 1,015 27,863 10,555 115 39.548 1956 226.5 49 4 177 885 10,671 2,762 532 14.650 1957 210.0 30 8 179 2.590 24,283 15,344 773 42.990 1958 193.5 156 176 1.977 48.458 14,149 1,587 66,171 1959 167.5 20 148 2.820 26.456 14,184 1,764 45,224 1960 160.0 314 129 1,619 14.310 10,533 1,240 27,702 1961 168.4 29 139 1,098 22,468 12,046 1,270 36,882 1962 139.2 22 6 117 2,539 19,009 12,156 1.287 34,991 1963 132.0 163 116 1,264 25,535 11,785 1.542 40,126 1964 142.5 108 131 3,143 26,991 13,279 1.469 44,882 1965 133.4 196 113 2,200 18,706 10,565 731 32,202 1966 150.0 107 138 1,673 17,826 11,548 1.338 32,385 1967 142.0 70 135 2,640 22,176 12,503 2.185 39,504 1968 117.5 126 105 1,725 12,888 14.932 721 30,266 1969 116 8 66 110 323 15.024 10.800 1.631 27.778 1970 1158 103 105 916 16.337 15.533 1,402 34,188 'Sources tor data in Table 1 and tootnotes are given belov^r Pups born 1 950-60 table 1 1 2 Irom Ctiapman 1 1 973) . 1 961 -65 and 1 969-70, table 1 4 from Marine Mammal Biological Laboratory ( 1 971 ■). 1 967-68, table 1 from l^anne lulammal Division (1976^) A 1 1 sex ratio is assumed (Kenyon et al 1954, H Kaiimura pers common ) Dead pups 1 950-60 (except 1 952), appendix table 39 from Marine Mammal Biological Laboratory ( 1 961 ) . 1 952, counts (Irom same source) on sample rookenes only, extrapolated to island total Irom average contribution ol these rookeries to known totals in 1951 and 1953 1961-69 table A.12 Irom Manne Mammal Biological Laboratory (1971) A 1 1 sex ratio is assumed (Kenyon et al 1954, M C Keyes pers common ) Living pups Pups born less dead pups, rounded to nearest thousand Kill by age 1950-56 year classes, table 1 trom Marine Mammal Biological Laboratory (1961'), 1957-64 year classes, table 1 trom Manne Mammal Biological Laboratory (1971), 1965-70 year classes table 1 from Marine Mammal Division (1976^) "Marine Mammal Biological Laboratory 1 971 Fur seal invesligation, 1 970 Unpubl manuscr , 1 55 p US Dep Commet . Natl Mar Fish Serv Northwest Fish Cent , Seattle, WA 98112 "Marine Mammal Division 1976 Fur seal investigations, 1975 Unpubl manuscr , 1 15p US Dep Commer Natl Mar Fish Serv , Northwest Fish Cent , 'Marine Mammal Biological Laboratory 1961 Fur seal investigation, Pribilol Islands, Alaska Unpubl manuscr , 148 p US Fish Wildl Serv , Bur Commer Fish 1950). However, the average numbers of pups migrating from land and of seals harvested at age Syr are approximated for the 1920-22 year classes in order to include in the yield-pup relationship a data point for the relatively small pup population then present. It should be mentioned that basic data were not taken during 1925-46 from which to estimate annual pup production. The 1920-22 averages are based on kill data from Lander and Kajimura^ and on pup data from Kenyon et al. ( 1954). The average number of pups born annually on St. Paul Island during 1920-22 was approximately 150,700. Their mean mortality rate on land was 2.2'7f , so an average of about 74,000 male pups migrated to sea annually. Be- cause the harvest always has been selective for animals the size of 3- and 4-yr-olds, these 1920-22 year classes contributed to the kills mainly in 1923-26. The annual average kill then was 14,300, of which about 9,100 were age 3 yr assuming the same average (64'7f ) as in the kills from the 1950- 70 year classes (Table 1). 'Lander, R. H, and H Kiyimura, 1976 Status of northern fur seals. Food and Agriculture Organization of the United Nations, Scientific Consultation on Marine Mammals, Bergen, Norway, August 31-September 9, 1976, 50 p. (Unpubl. rep. I The kill of 3-yr-olds is used as an index of abun- dance at that age. The assumption is justified reasonably well by the generally stable harvest- ing regime and the usual predominance of this age group in the kills. Annual population monitoring and behavioral data (Bartholomew and Hoel 1953; Peterson 1968) show the median date of birth on St. Paul Island is about 8 July, pup mortality on land is essentially over by mid-August, and the median date when pups migrate to sea is around 1 November. Survi- val of pups on land is calculated as the ratio of living pups to pups born (Table 1). Few seals haul out on land until 24 mo of age, and survival is estimated for the first 20 mo at sea. These ocean survival rates are calculated from the data for living pups and age-specific kills (Table 1) and from the model of Lander (1975) with time intervals appropriately modified. Results Figure 1 shows wide fluctuations in the kill at age 3 yr around the regression line for pups born. After the effects of pup mortality on land are re- moved, high variability persists around the line 312 40 z < in o 20- PUPS BORN 50 •53 Ul •58 UJ > PUPS MIGRATING < FROM LAND X 40- 53 '50 t/1 ' _J < 51 ^^ UJ U1 ^^ •s? LU _) 63 61 59 y^ •ss < 5 6 7A , .'57 ll- 20- ^1^ ^ 54 o 70, ^^ • 56 cc ly* .69 UJ y •60 CD ^y^ 68 2 ^^ •56 3 *20-22 2 90 150 210 NUMBER OF MALE PUPS (THOUSANDS) FiGLTRE 1.— Yield-pup relation for male fur seals of the 1920-22 and 1950-70 year classes from St Paul Island Least squares regression lines are shown for pups bom (a = 2.341. 6 = 0.126) and for pups migrating from land (a = 3.740, b = 0.188). for pups migrating from land. Most of the varia- tion in abundance at age 3 yr is evidently due to changes in the ocean survival rate undergone by the different year classes, not to changes in the rate of pup survival on land. Estimated survival rates for the 1950-70 year classes are in Table 2 (ocean survival could not be estimated for the 1920-22 year classes without age composition data). The means and ranges of survi- val estimates in Table 2 are 87<7f ( 78-95'7f ) for pups on land, 40% (18-497^ ) for the first 20 mo at sea, and 35^?^ (14-45'7f ) for both stages between birth and 2 yr of age. Figure 2 shows a statistically significant associ- ation between the ocean and land survival esti- mates (r = 0.67,P<0.01). Conditions of weather, feeding, and disease which promote good survival Table 2. — Estimated natural survival rates of male fur seals from St. Paul Island in two stages from birth to age 2 yr, 1950-70 year classes. Year class < o 45 o 5 35- 25- Pups on land First 20 mo at sea until start ot kill at age 2 yr Birth to age 2 yr 1950 88 041 036 1951 084 42 035 1952 0,91 46 42 1953 082 38 031 1954 79 30 24 19SS 84 33 28 1956 78 18 14 1957 85 37 31 1958 92 49 45 1959 88 43 38 1960 81 34 0,28 1961 083 39 32 1962 0,84 043 36 1963 088 47 041 1964 92 47 43 1965 085 041 35 1966 0.92 36 0.33 1967 95 42 40 1968 089 42 37 1969 94 38 36 1970 091 46 042 All 87 40 35 78 86 94 ESTIMATED SURVIVAL OF PUPS ON LAND (%) Figure 2. — Relation of estimated survival rate during first 20 mo at sea to estimated survival rate of pups on land for male fur seals of the 1950-70 year classes from St. Paul Island. Functional regression line shown (Ricker 1973) has intercepts = 0.830 and slope [' = 1.425. of pups on land apparently equip them to survive relatively well at sea. As in Figure 1, however, the wide scatter about regression is prominent — emphasizing again that events at sea contribute 313 heavily to fluctuations in the survival of different year classes. Values in Tables 1 and 2 were also analyzed under the multiple linear regression model Y = A + B,Xi + 52^:2 + B3X3 + E where y = kill at age Syr in thousands, Xj = male pups born in thousands, X2 = survival rate pups on land, and X3 = survival rate during the first 20 mo at sea. £ is a random error term; the intercept A and slopes fi, are parameters to be estimated. Table 3 shows that multiple regression is highly significant (F = 26.60, P<0.001). Given that the pup survival rate on land is not significant (dele- tion of A'2 causes no change in R^ here), 100 R'^ = 82% of the annual variation in estimated abun- dance at age 3 yr, as indexed by the kill, is explained by annual changes in pup production and in the survival rates of different year classes during their first 20 mo at sea. The remaining variability, 18%, is due to random sampling errors and possibly to systematic errors. Discussion This report helps to quantify the importance of early ocean mortality in determining the average number of males available for harvest at age 3 yr and their pronounced annual fluctuations. Ken- yon et al . (1 954 ) speculated that only half the pups survive the attempted transition from a milk diet T.\BLE 3. — Statistics and tests for linear regression of male seals killed on St. Paul Island at age 3 yr( thousands) from the 1950-70 year classes (V ) on pups born (A', . thousands), estimated survival rate of pups on land i.Vji, and estimated survival rate during the first 20 mo at sea until age 2 yr (Xj ). Hem Calculated value Source of sum of squares, degrees of freedom, and mean square Multiple regression Deviations Total Test of multiple regression Square ot multiple correla- tion Parameter estimates and variances a.s'. Tests of individual regresions Pups born Land survival rate Ocean survival rate 1.53160/3 = 510 53 326-2617 = 19 19 1.857 86/20 ^ 92 89 F -- 510 53/19 19 ^ 26 60" R' = 1,53160/1.857.86 = 0.82 -70 355. 533 294 21 389, 753 857 103012, 350 151 on the Pribilof Islands to the quest for fishes and squids in a stormy environment after the islands are left behind. The authors stated that starvation during prolonged storms is a direct cause of death and noted that unusually large numbers of young seals from the 1949 year class were washed ashore on the Washington coast in emaciated condition during the severe winter of 1949-50. Ichihara ( 1974) postulated that the apparently higher mor- tality of males between birth and age 3 yr (Chap- man 19641 was due to the greater proportion of males wintering in stormy northern areas than in calmer waters to the south where females pre- dominate. Literature Cited Bartholoiview, G. a., Jr., and p. G. Hoel. 1953. Reproductive behavior of the Alaska fur seal, Cal- lorhinus ursinus. J. Mammal. 34:417-436. CHAPMAN, D. G. 1961. Population dynamics of the Alaska fur seal herd. Trans. North Am. Wildl Nat. Resour. Conf. 26:356-369. 1964. A critical study of Pnbilof fur seal population esti- mates. U.S. Fish Wildl. Serv., Fish. Bull. 63:657-669. 1973, Spawner-recruit models and estimation of the level of maximum sustainable catch. Rapp. P.-V. Reun. Cons. Int. Explor. Mer 164:325-332. Ichihara, T. 1974, Possible effect of surface wind force on the sex- specific mortality of young fur seals in the eastern Pa- cific, Bull, Far Seas Fish, Res, Lab, (Shimizul 11:1-8, Kenyon, K. W., V, B. Scheffer, and D. G. Chapman, 1954, A population study of the Alaska fur-seal herd. US. Fish Wildl. Serv., Spec. Sci. Rep. Wildl. 12, 77 p. Lander. R. H. 1975, Method of determining natural mortality in the northern fur seal \Callorhinus ursinus) from known pups and kill by age and sex. J. Fish. Res. Board Can, 32:2447-2452. Marine Mammal Biological Laboratory, 1971, Fur seal investigations, 1969. U.S. Dep. Commer., Natl Mar. Fish. Serv., Spec. Sci. Rep Fish. 628, 90 p. Peterson, R, S, 1968. Social behavior in pinnipeds with particular refer- ence to the northern fur seal. In R. J. Harrison et al. (editors), The behavior and physiology of the pinnipeds, p. 1-53. Appleton-Century-Crofts, N.Y. Richer, W, E, 1973. Linear regressions in fishery research. J. Fish. Res. Board Can. 30:409-434. SCHEFFER. V. B. 1950, Growth layers on the teeth of Pinnepedia as an indi- cation of age. Science (Wash,, DC) 112:309-311 ROBERT H. Lander t, = 203/v_0 0qi 6 42" , = 21 389/v'753857 =^0 78 103 012'v'350,157 = 550" Northwest and Alaska Fisheries Center National Marine Fisheries Sennce, NOAA 212h Montlake Boulevard East Seattle. WA 98112 314 NOTICES NOAA Technical Reports NMFS published during the last 6 mo of 1978. Circulars 414. Synopsis of biological data for the winter flounder, Pseudopteuronectes americanus (Walbaum). By Grace Klein-MacPhee. November 1978. ill + 43 p., 21 fig., 28 tables. Also FAO Fisheries Synopsis No. 117. 415. A basis for classifying western Atlantic Sci- aenidae (Teleostei: Perciformesl. By Labbish Ning Chao. September 1978, v + 64 p., 41 fig., 1 table. 416. Ocean variability: Effects on U.S. marine fishery resources- 1975. Jul ien R. Goulet.Jr. and Elizabeth D. Haynes, editors. December 1978, iii + 350 p. 417. Guide to the identification of genera of the fish order Ophidiiformes with a tentative classification of the order. By Daniel M. Cohen and Jorgen G. Nielsen. December 1978, vii + 72 p., 103 fig., 2 tables. 418. Annotated bibliography of four Atlantic scom- brids: Scomberomorus brasiliensis, S. cavalla, S. maculatus, andS. regalis. By Charles S. Manooch III. Eugene L. Nakamura, and Ann Bowman Hall. De- cember 1978, iii + 166 p. Special Scientific Report — Fisheries 726. The Gulf of Maine temperature structure between Bar Harbor, Maine, and Yarmouth, Nova Scotia, June 1975-November 1976. By Robert J. Pawlowski. De- cember 1978, iii -I- 10 p., 14 fig., 1 table. NOAA Technical Reports NMFS are available free in limited numbers to Federal and State government agencies. They are also available in exchange for other scientific and technical publications in the marine sciences. Individual copies, if available, may be obtained by purchase from the Superintendent of Documents or by writing to User Services Branch (D822.), Environmental Science Information Center. NOAA, Rockville, MD 20852. 315 INFORMATION FOR CONTRIBUTORS TO THE FISHERY BULLETIN Manuscripts submitted to the Fishery Bulletin will reach print faster if they conform to the following instructions. These are not absolute requirements, of course, but desiderata. 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The sequence of the material should be: TITLE PAGE ABSTRACT TEXT LITERATURE CITED APPENDIX TEXT FOOTNOTES TABLES (Each table should be numbered with an arable numeral and heading provided) LIST OF FIGURES (Entire figure legends) FIGURES (Each figure should be numbered with an arable numeral; legends are desired) ADDITIONAL INFORMATION Send the ribbon copy and two duplicated or carbon copies of the manuscript to; Dr. Jay C. Quast, Scientific Editor Fishery Bulletin Northwest and Alaska Fisheries Center Auke Bay Laboratory, National Marine Fisheries Service, NOAA P.O. Box 155, Auke Bay, AK 99821 Fifty separates will be supplied to an author free of charge and 100 supplied to his organiza- tion. No covers will be supphed. Contents-continued OLLA, BORI L., ALLEN J. BEJDA, and A. DALE MARTIN. Seasonal dispersal and habitat selection of cunner, Tautogolabrus adspersus, and young tautog, Tautoga onitis, in Fire Island Inlet, Long Island, New York 255 HUGHES, STEVEN E., and GEORGE HIRSCHHORN. Biology of walleye pollock, Theraga chalcogramma, in the western Gulf of Alaska, 1973-75 263 Notes HOBSON, EDMUND S., and JAMES R. CHESS. Zooplankters that emerge from the lagoon floor at night at Kure and Midway Atolls, Hawaii 275 WENZLOFF, D. R., R. A. GREIG, A. S. MERRILL, and J. W. ROPES. A survey of heavy metals in the surf clam, Spisula solidissima, and the ocean quahog, Arcfjca islandica, of the Mid-Atlantic coast of the United States 280 OVERHOLTZ, WILLIAM J., and JOHN R. NICOLAS. Apparent feeding by the fin whale, Balaenoptera physalus, and the humpback whale, Megaptera novaengliae, on the American sand lance, Arnmodytes americanus , in the northwest Atlantic . 285 WILLIAMS, JOHN G. Estimation of intertidal harvest of Dungeness crab, Cancer magister, on Puget Sound, Washington, beaches 287 TARGETT, TIMOTHY E. A contribution to the biology of the puffers Sphoeroides testudineus and Sphoeroides spengleri from Biscayne Bay, Florida 292 HUI, CLIFFORD A. Correlates of maturity in the common dolphin, Delphinus delphis 295 ALLEN, LARRY G. Larval development ofGobiesox rhessodon (Gobiesocidae) with notes on the larva oi Rimicola muscarum 300 BAILEY, KEVIN, and JEAN DUNN. Spring and summer foods of walleye pollock, Theragra chalcogramma, in the eastern Bering Sea 304 DIETRICH, CHARLES S., JR. Fecundity of the Atlantic menhaden, Brevoortia tyrannus 308 LANDER, ROBERT H. Role of land and ocean mortality in yield of male Alaskan fur seal, Callorhinus ursinus 311 Notices NOAA Technical Reports NMFS published during the last 6 mo of 1978 315 , GPO 696-364 ..< °?^ c Fishery Bulletin Mariiie BiolDgical laliordiOJj LIBRARY OCT 24 1979 Vol. 77, No. 2 Woods Hole, Mass. April 1979 ■^ CLARK, COLIN W., and MARC MANGEL, Aggregation and fishery dynamics: a theoretical study of schooling and the purse seine tuna fisheries 317 WEINSTEIN, MICHAEL P. Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape Fear River, North Carolina 339 SCOTTO, LIBERTA E. Larval development of the Cuban stone crab, Menippe nodi- frons (Brachyura, Xanthidae), under laboratory conditions with notes on the status of the family Menippidae 359 PELLA. JEROME J., and TIMOTHY L. ROBERTSO