FISHERY BULLETIN: VOL. 83, NO. 3 



between visceral fat volume and gonad volume in 

 five offshore species of rockfish: Sebastes entomelas, 

 S. paucispinis, S. goodei, S. pinniger, and 5. 

 flavidus. Based on Roberts' suggestion and the 

 general literature on fat cycles in fishes, we expected 

 to find complementary cycles of fat and gonad 

 volume, indicating that reserves are used in repro- 

 duction. We used visceral fat volume as a convenient 

 index of the timing and magnitude of seasonal 

 changes in reserves, explicitly assuming that 

 reserves stored elsewhere would change coinciden- 

 tally (Delahunty and de Vlaming 1980). Since we did 

 not measure total reserves, our data on visceral fat 

 volume cannot be applied to quantitative studies of 

 energ\' budgets, but are most useful for examining 

 seasonal changes and making comparisons within a 

 group of closely related species. 



The use of gonadal volume as an index of reproduc- 

 tive activity requires some explanation. In males, 

 gonadal volume is a good index of the timing of 

 gametogenesis. In females of this live-bearing genus, 

 however, gametogenesis is often reflected only in the 

 initial increase of gonadal volume. Following fertili- 

 zation (which may occur some time after copulation, 

 due to sperm storage [Sorokin 1961; Echeverria 

 1981''; Boehlert and Yoklavich 1984]), ovarian 

 volume continues to increase during a gestation 

 period that lasts a month or so (Moser 1967). There 

 may be some postzygotic nutrition of embryos dur- 

 ing this time (Boehlert and Yoklavich 1984), but 

 much of the increase in volume is due to the ac- 

 cumulation of water (Moser 1967). In some species of 

 Sebastes that spawn more than once a year, 

 gametogenesis takes place again late in the repro- 

 ductive season of females. Among the species con- 

 sidered here, S. paucispinis and 5. goodei are clearly 

 multiple spawners (Moser 1967; MacGregor 1970), 

 and Echeverria^ has presented some evidence for 

 multiple spawning in S. pinniger. 



MATERIALS AND METHODS 



Party boat and commercial rockfish catches were 

 sampled weekly, as a part of a large-scale study, by 

 personnel from the National Marine Fisheries Ser- 

 vice (Tiburon Laboratory) and the California Depart- 



*Echeverria, T. 1981. Maturity in six species of roci<fish 

 (Pisces, Scorpaenidae, Seba.'<tt's). [Abstr.] Proceedinji^s of the 

 1981 Western (Iroundfish Conference. 



^Echeverria, T. 1983. Maturity and seasonahty of the 

 rockfishes (Scorpaenidae: Seh(ustes) of central California. Unpulil. 

 manuscr., 60 p. Southwest F'isheries Center Tihuron Laboratory. 

 National Marine f^isheries Service, NOAA, 31.50 Paradi.se Drive, 

 Tiburon. CA 94920. 



ment of Fish and Game, at northern California 

 fishing ports between Crescent City (lat. 41°N) and 

 Morro Bay (35° N). The species sampled depended on 

 the day's catch. Samplers measured the total length 

 of each specimen to the nearest millimeter and 

 removed the viscera and gonads for preservation in 

 10% Formalin^ in seawater. 



In the laboratory, fat tissue was dissected from the 

 viscera and its volume estimated by water displace- 

 ment in graduated cylinders. In some samples, a 

 small amount of fat had liquified. The volume of this 

 liquid was estimated and added to total fat volume. 

 Gonads were also removed and their volume 

 measured as above. The state of development of 

 ovaries and testes was scored according to indices 

 based mainly on gonad morphology and coloration 

 (Moser 1967; Gunderson et al. 1980). Histological 

 preparations of small gonads were used to confirm 

 sex and state of maturity. Data for species, sex, total 

 length, stage of maturity, and fat and gonad volume 

 were stored using a computer. 



Data on visceral fat volume were analyzed for col- 

 lections made between March 1980 and February 

 1981, inclusive. Measurements of gonad volume 

 were begun in June 1980 and continued until May 

 1981 to obtain a full year of data. For each species, 

 data were pooled over all ports of collection and 

 divided quarterly, as follows: spring (March-May), 

 summer (June-August), fall (September-November), 

 and winter (December-February). Quarterly division 

 of data gave good sample sizes for most seasons, yet 

 still allowed seasonal separation. Primary production 

 is relatively low off California during fall and winter, 

 but is greater during most of spring and summer, 

 when coastal upwelling occurs (Bolin and Abbott 

 1963). 



To facilitate comparisons, visceral fat volume and 

 gonad volume were expressed as log-transformed 

 power-function regressions of volume on fish length. 

 The power equation is: 



V = aL'\ 



where V is volume, L is total length, and a and h are 

 estimated parameters. This equation is often used to 

 express the relationship between volumetric 

 measures, such as fecundity, and linear measures, 

 such as length (Bagenal 1978; Glebe and Leggett 

 1981a; de Vlaming et al. 1982). Logarithmic trans- 

 formation to 



In V = In + 6 In L 



^Reference to trade names does not imply endorsement by the Na- 

 tional Marine Fisheries Service, NOAA. 



300 



