SEASONAL CYCLES OF FAT AND GONAD VOLUME IN 



FIVE SPECIES OF NORTHERN CALIFORNIA ROCKFISH 



(SCORPAENIDAE: SEBASTES) 



Patrick J. Guillemot, ' Ralph J. Larson,^ and William H. Lenarz^ 



ABSTRACT 



Seasonal changes in visceral fat volume and gonad volume are compared in five species of rockfish from 

 northern and central California: Sebastes entomelas, S. paucispinis, S. goodei, S. pinniger, and S. flairidus. 

 In these species, visceral fat was deposited between spring and fall, at the same time as gametogenesis. 

 Visceral fat declined in volume between fall and spring, coinciding with the decline in volume of testes and 

 preceding the release of embryos in females. We suggest that increased feeding during the summer upwell- 

 ing season provides the energy for simultaneous fat accumulation, gametogenesis, and perhaps somatic 

 growth. During subsequent seasons of presumed food storage, these rockfishes may utilize visceral fat 

 reserves for maintenance. This pattern of fat deposition and utilization may contribute to the long life and 

 repeated reproduction of rockfishes, at the expense of current fecundit\' and growth. 



Our data also suggest that rockfishes which spawn only once during the reproductive season have fat 

 cycles of greater magnitude than those spawning more than once a year. Of the species that we studied, the 

 apparent single spawners S. entomelas and S. flaindus have more northerly geographic distributions and 

 larger fat cycles than the multiple spawners S. goodei and 5. paucispinis. It is possible that the shorter and 

 more pronounced productive season in the north leads to a greater need for fat reserves during winter and 

 makes the wintertime production of additional batches of eggs energetically difficult. 



The seasonal storage and utilization of lipid (and 

 nonlipid) reserves are important in the metabolic 

 activities and overall life histories of many animals 

 (Love 1970; Shul'man 1974; Derickson 1976a and 

 associated papers). While cycles of lipid storage and 

 utilization are generally associated with seasonal 

 changes in food availability (Derickson 1976b) or 

 metabolic demands (Lawrence 1976), the functions 

 of lipid storage are varied. 



In many fishes, reserves are used primarily in 

 reproduction, as indicated by complementary cycles 

 of lipid content and reproductive activity (Lasker 

 1970; Shchepkin 1971a, b; Schevchenko 1972; 

 Shul'man 1974; Tyler and Dunn 1976; Wootton and 

 Evans 1976; Lasker and Smith 1977; Diana and 

 MacKay 1979; Delahunty and de Vlaming 1980; 

 Patzner 1980; Hunter and Leong 1981). The 

 seasonal accumulation of sufficient reserves may be 

 a prerequisite for sexual maturity in some fishes (lies 

 1974), and the amount of material stored may in- 

 fluence fecundity (Tyler and Dunn 1976). Reserves 



'Southwest Fisheries Center Tiburon Laboratory, National 

 Marine Fisheries Service, NOAA, Tiburon, CA; present address: 

 3298 Madera Avenue, Oakland, CA 94619. 



^Department of Biological Sciences, San Francisco State Univer- 

 sity, San Francisco, CA 94132. 



^Southwest Fisheries Center Tiburon Laboratory, National 

 Marine Fisheries Service, NOAA, 3150 Paradise Drive, Tiburon, 

 CA 94920. 



Manuscript accepted August 1984. 



FISHERY BULLETIN: VOL. 83, NO. 3, 1985. 



may also be used in migration (Robertson and Wex- 

 ler 1960; Dotson 1978; Glebe and Leggett 1981 a, b), 

 and, when used in spawning migrations, may con- 

 tribute indirectly to reproduction. 



Slobodkin (1962) and Calow (1977), however, 

 noted that fat deposition may actually detract from 

 reproduction, particularly when fat deposition and 

 reproduction are concurrent. In such cases, reserves 

 are often used instead for maintenance during 

 periods of food scarcity (Calow and Jennings 1977), 

 enhancing the opportunity to reproduce in the 

 future. Some fishes seem to use reserves both for 

 reproduction and maintenance, when spawning oc- 

 curs during periods of food scarcity or fasting 

 (Wilkins 1967; MacKinnon 1972; lies 1974; 

 Newsome and Leduc 1975; Foltz and Norden 1977; 

 Dawson and Grimm 1980; Pierce et al. 1980; Glebe 

 and Leggett 1981 a, b). The interpretation of such 

 cases is complex, since reproduction and 

 maintenance may be competing concurrently for 

 reserves. 



Roberts (1979) noted that fat was deposited 

 seasonally around the viscera of two species of 

 shallow-water rockfish, Sebastes mystinus and S. 

 melanops. He suggested that the cycle of fat deposi- 

 tion and utilization was related to seasonal changes 

 in the abundance of food and to reproduction. 



In this paper we examine the seasonal relationship 



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