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181

Sexual dimorphism in four of rockfish genus Sebastes (Scorpaenidae)

Tina Wyllie Echeverria Soiithwest Fisheries Center Tihurori Laboratory, Natioriril Maririe Fisheries Service, NOAA, 3150 Paradise Drive) Tibirron, CA 94920, U.S.A.

Keywords: Morphology, . , Parental care. Discriminant analysis

Synopsis

Sexual dimorphisms, and factors influencing the evolution of these differences, have been investigated for four species of rockfish: Sebastcs melanops, S. fluvidus, S.mystiriiis. and S. serranoides. These four species, which have similar ecology. tend to aggregate by species with males and staying together throughout the year. In all four species adult females reach larger sizes than males, which probably relates to their role in reproduction. The number of produced increases with size, so that natural selection has favored larger females. It appears malzs were subjected to different selective pressures than females. It was more advantageous for males to mature quickly, to become reproductive, than to expend energy on growth. Other sexually dimorphic features include larger eyes in males of all four species and longer pectoral fin rays in males of the three piscivorous species: S. rnelanops, S. fhvidiis. and S. serranoides. The larger pectoral fins may permit smaller males to coexist with females by increasing acceleration and, together with the proportionately larger eye, enable the male to compete successfully with the tb capture elusive prey (the latter not necessarily useful for the planktivore S. niy.ftiriiis). Since the size of the eye is equivalent in both of the same age, visual perception should be comparable for both sexes.

Introduction tails (Xiphophorus sp.) and gobies (Gobius sp.) as fin variations, in (Paecilia sp.) and Natural selection is a mechanism of evolution (Labrus sp.) as color variations, in eels (Anguilla which can influence physical characteristics of a sp.) and mullets (Mugil sp.) as size differences. and species, characteristics which reflect selective pres- in silurids (Oinpok sp.) (Rao & Karamchandani sures in the species environment. Sexual selection 1971) and sculpins (Myoxocephalus sp.) its mor- is a component of natural selection that acts inde- phological variations in body proportions (Breder pendently upon males or females. Sexual dimor- & Rosen 1966). phism can result from either component. In , secondary sexual dimorphisms are Sexual dimorphisms, which occur in every major often associated with species that have internal group of , are commonly manifested in fertilization or protection of the eggs or young by a as size differences, in as color varia- parent (Breder & Rosen 1966). Despite the wide- tions, in reptiles as defensive structures, and in spread relationship between as sounds. Fishes of both fresh and salt and secondary , one of the most water also exhibit sexual dimorphisms: in sword- speciose groups of live bearers in the northeast Pacific Ocean, the rockfishes (L~chasrr.s)with ap- cal differences between the sexes of any one species proximately 70 species occurring in that region. that could be used. in themselves. to characterize docs not show obvious sexual dimorphisms. the sexes. and (3) if there are differences. what Four species of Sc~hrrcrc~s\vex xtudied: S. their significance might be. ITIPIN~IO~S.the black rockfish: S. ,f%c~.cdus,the yel- Working within the definitions of selection that lowtail rockfish: S. /TzJ.sriiirrs. the blue rockfish: and hwc been rnade here. an attempt will be niitde to 5. .\err.rrrwirlc.s, the olive rockfish. All four species discern which coniponent - natural or sexual selec- are very similar in and size. ivith con\ ci tion- ma! ha\e exerted the greater influence in any interorbital spaces. weak head spines and ;I dusky sexually dimorphic feature found in these four spe- olive-to-black coloration. all key characters used in cies of .Sehrr.rtr.s. Natural celection will be credited the identification of rockfish (Miller K: Lea 1970). for those features that primarily affect the survival Similarities include morphologies and reproduc- of thc entire species, while sexual selection will be tive characteristics while they are seixiratcd ecolo- limited to those features'that affect the reproduc- gically by different diets. feeding times. and depth tive advantage of one individual over another. distributions. These four species have heen studied more than other rockfish because they comprise ;t large part of the commercial ,ind sport-fishing land- Methods ings. and iire readilq accesible in large aggrega- tions near shore. Rockfish were collected throughout 1977 from In Sc1~~c.sthe contribution to thc siirvi\,aI of three localities along the coast of central Califor- young is priniaril? accomplished by the female. nia: Point Reyes. the Farallon Islands. and Cordell Fertilization is internal with possible storage of Bank (Fig. I). These localities lie at the cornersofa by the female (Sorokin 1967). During geAta- triangle covering roughly 250 square miles. tion the arterial suppl!, to the serves for the relatively limited area was chosen because Miller & exchange of metabolic wistc\ (Moser 1967) and the Geibel (1973) showed that growth rates in blue ovarian fluid provides some nutrition for the de- rockfish from widely sepxated geographic areas veloping cmbroys (Boehlert & Yoklavich 1984). differed. used in the morphometric study were wries among \peck\. but is aln ;I>S collected as part of a survey of age and length in the large. increasing with the size of the fcniale (Phi- rockfisheb of central California (Sen 19S.1). and llips 1964. Boehlcrt et ill. 19x3). with some species constitute a subsarnple of the fish used in that sur- possibly having two brood\ per year (Moser 1007. \.e!'. MacGregnr 1970). In Sdmctc.s. selection ha\ fa- vored increasing 13)- means of large females capable of producing and acconi- modating large numbers of enibr!os. I-h c on1 y reports of morph ol ogi cii 1 d i ffe re n ce s 3S0N between sexes of Schrrste.s ;ire pro\,ided by Chen (Iq7l) and Moser (1967). Chen fouild sexual dinior- phism in Schtrstes I~//I~UISI~.S.with males having a shorter prc-iinal length but ;I greater ;inn1 haw. upper length. anal ray length. snout length and 0 10 20 prepelvic length (f'

Specimens were collected from the hook-and- tinued beyond the ages obtained in previous stud- line sportfishing fleet. Fish were filleted on board ies. the fishing boat. and the carcasses were collected The average length of the males and females at and handled in a standardized way to reduce the each age was used to compare growth rates be- variability in measurements which occurs between tween the sexes. The comparisons were made from whole fish and carcasses or fresh and frozen fish all fish sampled (Table 1). (Forrester 1967). In the laboratory the otoliths and the stage of gonadal development were (Sagitta) were collected, the gonad state was deter- determined in the laboratory. Sexes were identi- mined. and 23 body parts. in addition to standard fied by gonadal inspection: ovaries were charac- length, were measured. terized by an mass encased by the ovarian wall Ages of the four species were determined by while the testis were characterized by appearing counting one opaque and one translucent zone of solid in cross-section. Ovaries were classified as: the otolith. Annular growth increments were vali- immature, with developing eggs. eggs containing dated up to 12 years in the black rockfish by Six & eyed embryos or spent. Testis were classified as: Horton (1977), up to 12 years in the yellowtail immature, undergoing , or spent. rockfish by Kimura et ai. (1979), and up to 4 years Gonad states of specimens collected throughout in the olive rockfish by Love bt Westphal (1981). the year were used to determine the reproductive Ages of blue rockfish have been determined from seasonality. scale annuli and comparison between the growth Morphometric measurements were made with zones of the otoliths and scales showed similiar vernier calipers (+0.01 mm) on freshly thawed fish patterns (Miller & Geibel 1973). All researchers carcasses. The 24 body parts measured included: agreed that, for the ages studied, one opaque and total length, fork length, standard length. head one translucent zone are deposited per year. Fish length. length of the base of the anal fin, snout collected in this study also included individuals length, interorbital width, width of the orbit, older than those from previous studies and it was length of the upper jaw, lower jaw projection. assumed the reliability of the annual marks con- width of the pectoral tin base. longest pectoral fin

TXik/. Mc;iri st;riitliird Iciigfh (mm)iit iigc for rn;rlc\ (hl) ;rnd lcniiilcs (Fj in Ioiir \pecics 01 rochfish collccted during 1077. Numhera (N) 01 indi\idu;ils u\cd ICI ~;iI~iiliitcIcnsth in parcnthcses.

Agc (!I-) .s. ,ticlliriop.\ s. //ol~ir/irc s. lliv\/;~lii\ s. cc~r.rtrlroitlcr

M (N) F (N) M (N) F (N) M (N) F (N) M (N) F (N)

4 283 (4) 235 (4) 227 (8) 180 (3) 7 3x8 (3) 294 (7) 259 (S) 25Cl (13) __''9 (0) 234 (4) 258 (3) 2s.i (I) (1 326 (IS) 320 (27) 2x7 (5) 2s2 (3) 233 (IO) 267 (19) 294 (21) 30.1 (3) 7 351 (25) -336 (14) 300 (I I) 303 (IO) 756 (11) 270 (70) 313 (12) 33s (13) S ,377 (21) 3x3 (IO) 300 (15) 320 (IS) 26.5 (11) 204 (15, 321 (13) 339 (13) 4 is3 (21) 305 (Is) 323 (17) 330 (16) 26s (13) 302 (15) 336 (3) 365 (9) IO 3ss (20) 402 (IO) 331 (21) 340 (23) 275 (12) 315 (14) 349 (3) 3s') (11) II -105 (1-1) 423 (4) .I30 (35) 357 (26) 323 (11) 417 (7) 12 401 (7) 420 (4) 352 (2s) 361 (34) 34s (11) 419 (2) I -7 .3u3 (7) 421) (3) 35s (20) .ihl (40) 35s (I I) I4 304 ( 12) 3x3 (40) 342 (6) 15 38s (4) 39s (20j 373 (3) I h 308 (I I) 353 (2) 17 410 (7) 366 (4) 184

ray. longest pelvic spine, and the longest pelvic ray for significant differences there is a fairly high following the procedure described by Phillips probability that. by chance alone. at least one mea- (1957); the longest dorsal ray. longest dorsal spine, surement will show significant differences: the lengths of the three anal spines. and the longest P = 1-0.99" = 0.21. anal ray measured from the posterior point of in- The probability of two or more significant differen- sertion. the longest gill raker on the first arch, body ces due to chance alone is considerably lower: depths at the ventral fin and anal fin, and distance P = 1-0.99?-;-23! (0.01) (0.99)" = 0.02. between the anal pore and the anterior insertion of 22! the anal fin following the method of Holt (1959). This study showed two to four significantly dif- Morphometric measurements were subsampled ferent body parts per species (Table 2). Body parts for fish from throughout the size ranges used in the which differed by sex in at least one species were: age-length determinations. An attempt was made upper jaw length. pelvic spine length. longest anal to measure five fish from each centimeter-interval ray, first anal spine length, longest dorsal ray and of total length so that 100-200 fish of each species orbit width. Two of these body parts were signifi- were represented in the sample. Regressions were cantly different in at least three of the species used to determine the relationships between 23 (Table 2). The orbit width which was larger relative body parts regressed against standard length. to standard length in males of all four species. and Analysis of covariance was used to test for signifi- the longest pectoral fin ray was larger relative to cant differences (P41.01)) in the body parts be- standard length in males of the black. yellowtail tween males and females. and olive rockfishes. Sexual dimorphisms do exist Ontogenetic changes in proportions of the 23 in additional species of Sehastes than previously body parts regressed against standard length were documented (Chen 1971) although the differences also evaluated. By taking the mean standard length are slight (Echeverria 1980). at each age from the age-length curve and the Ontogenetic studies showed a proportional in- regressions the body part size at each age was crease in length or width with respect to growth and estimated. these changes often differed for the two sexes. For A computer program for discriminant analysis example. a longer upper jaw and ii longer anal (Nie et al. 1975) was used to determine the proba- spine occurred in males of Sehusfes melanops. The bility that sex could be identified. for a particular striking finding was that. in all four species studied. species. when given only body-part measurements. the orbit width and the pectoral fin ray length were related to age so that males and females of the same age had orbits the same width and pectoral fins rays Results the same length (Table 2). These results indicate that there are some real. although subtle. differen- In all four species, females were larger than males ces in the growth rates of some body parts. of the same age after 5-7 years of age (Table 1). The Discriminant analysis yielded correct assign- differences were only significant (P

Anal spine I ;lee SL male Pelvic spine ;1gc male SL male Pectoral fin ray ;I& male SL male male male Anal dcpth age female SI. female Anal ray age female SL female Dorsal ray age lemale SL female Orbit width ;1ge SL male male mile male Upper jaw ;I$ female SL male

and 60% in olive rockfish (Table 3). It is clear that indication that males and females segregate into there are some statistically significant differences different areas, however, the sex ratios may exhibit in the body proportions, but, because of the vari- some seasonal variability. It appears that, for the ability in the measurements, and the values of per- most part, both sexes of a species inhabit the same cent agreement, no combination of the measured area, occurring together in aggregations. body parts can be used to adequately predict the sex of these fish. Rockfishes tend to aggregate by species with the Discussion sexes in the same aggregations. Hallacher (1977) studied kelp-bed inhabiting species of rockfishes The study of a species’ morphology can provide and found that each species apparently occupied a insight into its natural history, particularly with particular space in the water column with regard to regard to selective pressures in its environment. In depth and bottom type. In addition to having vari- this study, 23 key morphological features of four ous spacial localities the species occur in different species of rockfish were examined in an attempt to geographic areas. On the sport-fishing trips identify previously undescribed sexual dimor- sampled in this study, the species were not of equal phisms. These morphological data, when com- abundance at the various collection localities bined with known aspects of the life history of these (Table 4). When a species occurred both sexes species, provide clues to the evolution of sexual were present. The sampling technique does not dimorphism in rockfishes. allow for a critical examination of the relationship Sexual size dimorphism is usually attributed to between the sexes in an aggregation. There is no sexual selection, having evolved with respect to 186

Ttr/dc .? Di\criminant values used to assign sex from mor- Ttrhl(, 4. Distribution of the sample for the lour species ol phoiiictric d;it;i in lour \pecics of rockfish. the percent predic- rockfish u\cd in the age-length study; the iircii they were fished tiihility lroin the :iiialysi\. and ;I test sample of other fish. iiiid the number of males (M) or females (F) sampled.

Body parr Discriminant value Point Reycs Fnrallon la. Cordell Bank MFMFMF s. l?leltfrlo/~.s prcdictahility (N = 136) = 7ll'~L S.frrc/o/lo/,s 137 '16 0 I1 0 0 test cases (N = 31) = 74% S.//tfl,itlfr.\ 24 19 46 ox I19 113 Standard lensth 0.0424 s. fff\.F/irrfr\ 3s 64 31 71 0 I1 Orhit vidth I).1303 S. .\cwrrrroit/ec 7 4 51 53 32 Upper iiiw 0.1117 Pector;il ray -Il.2024 First anal \pine -0.765s 1979. Ghiselin 1974), where sexual selection favors con st ill1 t 4.1921 males diverting energy from growth into reproduc- -0.5215 iniile centroid tion at an earlier age than females. I c male cc 11t roid 0.3622 s. tlol~itlffc Sexual size dimorphism has been shown to occur prcdict;iliility (N = 113) = 75% in many species where there is a different age of te\t ciiscs (N = 24) = S0"h maturity for males and females (Wilson 1975). In St a nda rd le ngt h -l1.0609 some species, size dimorphism has been correlated Pectord fin -1). 1524 with a later onset of maturity in males (Wiley 1974, Orhit -0.1674 Pelv~spine I).I590 Ghiselin 1974). In rockfishes exhibiting size dimor- eOn\t;lllt 3 41x3 phism the situation appears to be reversed. Where niiilc cc lit roid -0.5471 size dimorphism occurs in Sebastes males are fc m ;I I c ce11 t 1-0 id 0,4471 smaller than females, with different growth rates s. /ffW/fIlf,\ between males and females tending to occur after prcdict;ibility (N = 193) = S9'% tc'st ciiscs (N = 45) = 92'b the fish are 6 to 8 years old (Westrheim & Harling Anal depth -0.1416 1975). For the yellowtail rockfish, S. fluvidiis, suf- Orhit 0.3SS4 ficient data exist to correlate the differential Dona1 ray ll.0035 growth rates with . Using informa- l~.lIO1Y Standard Icnsth tion from the same sample of yellowtail rockfish, Anal ray 0.009h const ant 6.9223 Fraidenburg (1980) obtained growth curves and iniilc' centroid 1.519s Gunderson et al. (1980) obtained size at sexual fc'rnale ceii t roid - 1.0.573 maturity. On the average. male yellowtails mature s c.er-,.trrroirl~~.s at 407 mm fork length and 8 years of age. Females prcdictaliility (N = 127) = 79% mature later, when they average 450mm fork tc\t c;i\es (N = 20) = 60'X St ;I nil ;i rd length 0.0601 length and 10 years of age. The size of an average 10 Pector;il ray I).1437 year old male is about 430 mm. Growth slows down Orhit -0.1377 at maturity so that males grow more slowly after 8 con\t;int -4.5387 years whereas growth in females does not slow intile centroid - 0.5634 until around 10 years. After the initial change in Icm;iIc centroid 0.8628 growth rates an average difference of about 20 mm remains constant, which agrees with results found reproductive success. This is observed in many for yellowtail rockfish examined in this study mammals where larger males have evolved due to (Table 1). Growth curves for the other species in competition for females (Darwin 1871). In the rock- this study show that males are smaller than fishes studied here. males were smaller than females. This occurs after age 7 in black rockfish females. which is often the case with invertebrates (Six & Horton 1977). after age 5 in blue rockfish (Darwin 1871) and many poikilotherms (Shine (Miller & Geibel 1973), and after age 4 in olive 187 rockfish (Love & Westphal 1981). Sexual size di- peting by copulating more frequently. With multi- morphism in black, blue and olive rockfishes prob- ple and the storage of sperm by females, ably also correlates to differing ages at which sexual intraovarian competition between the sperm of dif- maturity is attained by males and females. ferent males may contribute to the earlier maturity The widespread occurrence of sexual selection of males, the advantage of being reproductive ear- and its effect on sexual dimorphism is often related lier relating to sperm production and outweighing to a species’ and the degree of par- any disadvantage related to smaller size (Warner & ental investment (Wilson 1975). The evolution of Harlan 1982). Warner & Harlan suggest sexual parental care results in an increase in the survival of selection is responsible for the smaller size of males young (Balon 1984). Perrone & Zaret (1979) pro- in the livebearing dwarf surfperch, Micrometrus posed that parental care by males occurs when minimus. Similar sexual selection may be responsi- paternity is insured, as in nestspawning fishes ble for the smaller males found in some species of where the male guards the nest of eggs after fertil- Sebastes. ization. Parental care by females usually occurs Sexual dimorphisms exhibited as morphological before fertilization while yolk reserves are built up. differences have recently been shown to exist in or after fertilization if she retains the fertilized groups of marine fishes previously not known for eggs. dimorphic features (Gordina et al. 1974, Grant et Larger females and smaller males in Sebastes can al. 1977). The differences in body form in the spe- be understood in terms of differential parental in- cies studied here were slight, but statistically sig- vestment. Females, by retaining the fertilized eggs nificant, and were a result of different growth rates until young are ready to actively feed orally, con- of the body parts. tribute to the care and protection of the young. The disproportionate body parts in male Also, the numbers of eggs produced increases with Sebastes cannot, based on the available evidence, size; therefore, larger females release more young be firmly attributed to sexual selection. The rela- and contribute more to the gene pool. Natural tively large eye might be useful in locating females selection favors larger females. In Sebastes with or perceiving visual displays for mating. Fin dimor- internal fertilization and retention of the embryos, phisms may be used in sexual displays; however, the female makes the greatest parental investment, not enough is known about the behavior of Sebastes with investment by males limited to contributing spp. to relate these differences to sexual behavior. sperm. Perhaps they evolved not from sexual interactions Sexual size dimorphisms are predicted by Triv- but from sexes of different sizes occupying the ers’ (1972) theory which suggests, for home- same habitat, that is, males coexisting with females otherms, that males will compete among each larger than themselves. How the dimorphisms re- other for females if females are more involved with late to possible functional advantages will be dis- the offspring’s survival than males. This results in cussed for the two most common dimorphisms, the males being subject to selective pressures directly orbit width and the length of the pectoral fin ray. related to this competition, with larger more ag- Growth rate of the orbit is equal in males and gressive males being favored. Observations of pre- females (Table 2). Since females grow faster, males mating by the blue rockfish did not indicate aggres- have a larger orbit for their size. If the width of the sive behavior among males (Helvey 1982). suggest- orbit reflects the overall size of the eye, then the ing that sexual size dimorphism in Sebastes does not eye in males and females of the same age is compar- result from male competition for females. There is, able regardless of the size of the fish. The internal however, another possible battleground besides structure of the eye varies widely among species of aggressive behavior among males, and that is if the fishes and is adapted to a particular habitat (Munz opportunity exists for the sperm to compete. In S. 1971). The organization of a fish’s eye varies to aliitus there is a possibility that multiple mating perceive size, brightness, color, distance, orienta- occur (Lisovenko 1970). Males may thus be com- tion, and motion (Ingle 1971). Predaceous fishes, 188 for instance, have larger eyes which increases vi- Aggregations are a good defense against predators. sual acuity enabling them to detect motion better providing a confusion of darting bodies that makes (Walls 1967). In the black, yellotwail. blue. and it difficult for a predator to home in on a particular olive rockfishes the eyes of males, although pro- prey (Hobson 1978). Being in aggregations also portionately larger, are probably functionally increases the habitat available to a species; hiding equivalent to females of the same age. This sug- places are not necessary because the aggregation gests strong selective pressure favoring visual serves the purpose (Hamilton 1971). Finally ag- ‘equivalence’ between the sexes. presumably re- gregating also helps keep the sexes together during lated to foraging and avoiding predators. a long mating season. Courtship and In higher , the main functions of pectoral in Sebastes apparently occurs over a period of at fins are to control orientation during swimming. to least a month. with extrusion of the young in any maintain a stationary position in the water column one species occurring during at least a 2 month (less important in fishes with swim bladders such as period. Sebastes), and to accelerate from a standing start (Gosline 1971). Species of Sehasres that aggregate in the water column frequently hover in one loca- Acknowledgements tion (Hobson & Chess 1976, Hallacher 1977, Moulton 1977). In this situation, the pectoral fin I wish to thank Kathy Fourre for her assistance in may be used to remain stationary within an ag- collecting and measuring the fish. Nancy Wiley for gregation and to assist in thrusts toward prey. Pre- support with the computer analysis, and Margaret sumably thrust speed would be less important to Bradbury and Bill Lenarz for their encourage- planktivores (blue rockfish) and, accordingly, may ment, guidance and helpful criticisms throughout account for pectoral fin ray dimorphism occurring this study. only in the three more piscivorous species (black, yellowtail, and olive rockfishes). The pattern suggests that this characteristic may be a response to the References cited smaller males’ need to compete with larger females for elusive prey since they apparently aggregate Balon. E.K. 1984. Reflections on some decisive events in the together (Table 4). In fact, the black rockfish early life of fishes. Trans. Amer. Fish. Sac. 113: 178-385. Boehlert. G.W.. W.H. Barss & P.B. Lambersan. 1982. Fecun- (Moulton 1977), the yellowtail rockfish (Pereyra et dity of the widow rockfish. Sehnsres eriromeh. off the coast of al. 1969), the blue rockfish (Miller & Geibel 1973) Oregon. U.S. Fish. Bull. 80: 881-884. and juvenile olive rockfish (Hobson & Chess 1976) Boehlert. G.W. & M.M. Yoklavich. 1984. Reproduction. em- primarily aggregate by species. bryonic energetics. and the maternal-fetal relationship in the Separation of the sexes for part of the year occur viviparous genus Sebusres (Pisces: Scorpaenidae). Biol. Bull. 167: 353-370. in S. marinus (Sorokin 1961) and S. aliitiis (West- Breder. C.M. & D.E. Rosen. 1966. Modes of reproduction in rheim 1970, Gunderson 1974). Possible spawning fishes. National History Press, Garden City. 941 pp. migrations for the black rockfish was indicated by Chen. L.C. 1971. Systematics. variation. distribution. and biol- four females in the gravid and recently spawned ogy of rockfishes of the subgenus Sebastomus (Pisces. Scor- condition collected offshore in the central north paenidae. Sehnsrer). Bull. Scripps Inst. Oceanogr. Univ. Pacific (Dunn& Hitz 1969). Since the evidence is Calif. 18: 1-115. Darwin. C. 1871. The descent of . and selection in relation sparse that the sexes do separate, the species in this to sex. Murray. London. 705 pp. study probably co-occur, feeding, seeking shelter, Dunn. J.R. & C.R. Hitz. 1969. Oceanic occurrence of black and avoiding predators together. rockfish (Sebastodes mehops)in the central north Pacific. J. Since all four species form aggregations; the ad- Fish. Res. Board Can. 26: 3094-3097. vantages of associating appear to outweigh disad- Echeverria. T. 1980. Sexual dimorphism in four species of rock- fish. M. Sc. Thesis, San Francisco State University. San Fran- vantages that may arise due to size disparity be- cisco. 70 pp. tween the sexes in the same aggregation. Forrester. C.R. 1967. The shrinkage factor in measurements of 189

groundfish. J. Fish. Res. Board Can. 24: 691-693. scription of the in Sebastoiies. U.S. Fish Wildl. Serv.. Fraiden burg, M. E, 19x0. Yellowtail rockfish, Sehasres flavrdus, Spec. Sci. Rep. Fish. 596. 12 pp. length and age composition off California, Oregon and Wash- Miller. D.J. & J.J. Geibel. 1973. Summary of blue rockfish and ington in 1977. Mar. Fish. Rev. 42: 5456. lingcod life histories; a reef ecology study; and giant kelp, Ghiselin. M.T. 1974. The economy of and the evolution Macrocystis pyrifera. experiments in Monterey Bay. Califor- of sex. University of California Press. Berkeley. 346 pp. nia. Calif. Dep. Fish Game, Fish Bull. 158. 137 pp. Gordina, A.D.. L.A. Duka & L.S. Oven. 1974. Sexual dimor- Miller, D.J. & R.N. Lea. 1972. Guide to the coastal marine phism, feeding and reproduction of Gohius bucchichi in the fishes of California. Calif. Dep. Fish Game, Fish Bull. 157. Black Sea. J. Ichthyol. 14: 533-539. 249 pp. Gosline, W.A. 1971. 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