(;U1LLKM()TETAL.:SKAS()NAL CYCLES IN CALIFORNIA ROCKFISII 



initial gametogenesis, occurs during and shortly 

 after the spring-summer upwelling period, and deple- 

 tion occurs during and after a time of lower primary 

 production (Bolin and Abbott 1963). Roberts (1979) 

 noted that several species of inshore rockfish near 

 Monterey consumed more food during the summer, 

 when macroplankton (euphausiids) and juvenile rock- 

 fish were abundant. During the nonupwelling 

 season, juvenile rockfish and macroplankton were 

 less abundant, and adult rockfish consumed less food. 

 Love and Westphal (1981) found less food in the 

 stomachs of S. serranoides during the nonupwelling 

 season near Morro Bay. Gunderson (1977) noted a 

 "summer feeding season" in 5. alutus. Hobson and 

 Chess', however, found the gelatinous prey of 5. 

 mystinns to be more abundant during nonupwelling 

 periods off northern California. There is only limited 

 information on the seasonal food habits of the five 

 species studied here. Sehastes paucispinis is largely 

 piscivorous (Phillips 1964), while S. entomelas, S. 

 goodei, S. pinniger, and S. fiavidus feed on macro- 

 plankton and small fish (Phillips 1964; Pereyra et al. 

 1969; Brodeur 1982). Brodeur (1982) examined 

 seasonal changes in the diets of S. fiavidus and 5. 

 pinniger, and found that food consumption declined 

 during winter in 5. pinniger, but not in S. fiavidus. 

 However, Carlson and Barr (1977) found a pro- 

 nounced decline in activity during winter in 5. 

 fiavidus off Alaska, suggesting seasonal changes in 

 feeding. This hypothesis can be examined with con- 

 current data on food consumption and fat volume. It 

 is not mutually exclusive with other functions of fat 

 reserves, since some fat could also be used for migra- 

 tion, nourishment of embryos, or maturation of addi- 

 tional ova in multiple spawners. 



The wintertime use of reserves for maintenance, 

 however, is consistent with the overall pattern of 

 long life and repeated reproduction in rockfish (as 

 discussed also by Gunderson [1977]). As suggested 

 by Slobodkin (1962) and Calow (1977), summertime 

 fat deposition may exact a cost in current reproduc- 

 tion (if more gametes could be packed into rockfish 

 abdomens) or in future increases in gamete capacity 

 (through additional growth), but may help to ensure 

 survival. 



An interesting result of our study was the differ- 

 ence in magnitude of fat cycles among species, which 

 was particularly evident in females. These differ- 

 ences are correlated with both the frequency of 

 spawning and geographical distributions of the 



^Hobson, E. S., and J. R. Chess. 1981. Seasonal patterns in 

 trophic relationships of the blue rockfish, Sebaates 

 myatinu-ti. |Abstr.| Proceedings of the 1981 Western Groundfish 

 Conference. 



species. Females of S. entomelas and S. Jlaviduji had 

 fat cycles of high amplitude and volume, probably 

 spawn only once a year (Westrheim 1975; Eche- 

 verria footnote 5), and have northerly distributions 

 (Phillips 1957, 1964; Gunderson and Sample 1980; 

 Adams 1980). On the other hand, 5. paucispinis and 

 S. goodei had fat cycles of low amplitude and/or 

 volume, spawn more than once a season, at least in 

 southern California, and have southerly distributions 

 (Phillips 1957, 1964; Gunderson and Sample 1980; 

 Adams 1980). The case with S. pinniger is unclear. 

 Females seemed to have low-amplitude fat cycles, 

 but the small sample and small sizes of females in the 

 samples make conclusions tenuous. Echeverria (foot- 

 note 5) has some evidence for multiple spawning in 

 S. pinniger. If so, its northerly distribution would be 

 inconsistent with the pattern seen in the other 

 species. We will restrict our discussion to the remain- 

 ing four species, although further studies of S. pin- 

 niger may be instrumental in evaluating the sugges- 

 tions we make below. 



The small fat cycles of multiple spawners are prob- 

 ably not caused by their potentially greater repro- 

 ductive output, since fat deposition stops long before 

 the maturation of additional batches of ova. It seems 

 more likely that the magnitude of the fat cycle, fre- 

 quency of spawning, and geographical distribution 

 are all related. Boehlert and Kappenman (1980) sug- 

 gested that year-round spawning in southern popula- 

 tions of 5. diploproa served to increase reproductive 

 output in response to annual variation in the survival 

 of planktonic larvae. Multiple spawning in southern 

 populations and species may also be a response to the 

 more even seasonal distribution of upwelling in 

 southern vs. northern areas of the northeastern 

 Pacific (Bakun et al. 1974; Parrish et al. 1981; Smith 

 1978), as it affects planktonic larvae. However, the 

 more restricted upwelling season in northern waters 

 may also lead to larger and better defined seasonal 

 variation in the food supply of adults. A more pro- 

 nounced summertime pulse of food may enable 

 northerly species like 5. entomelas and S. fiavidus to 

 store large amounts of fat. Similarly, a more pro- 

 nounced decline in food during winter may make the 

 accumulation of such reserves necessary, and 

 preclude the maturation of additional batches of ova. 

 On the other hand, a more even seasonal distribution 

 of food in the south may enable southerly species like 

 S. paucispinis and S. goodei to produce additional 

 batches of ova during winter, and may also reduce 

 the need for wintertime reserves. These suggestions 

 are speculative, but it should be possible to compare 

 the seasonal variation of food consumption in species 

 with northern vs. southern distributions. 



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