304 



Fishery Bulletin 93(2). 1995 



to the fully developed ovaries 

 (63%). Summing all compo- 

 nents, the ratio of ovarian tis- 

 sue generated to somatic or- 

 ganic matter depleted was bal- 

 anced (i.e. 1.06). 



Discussion 



that mobilized by males. Depletion of liver protein 

 was similar in both sexes and accounted for only 

 about 10% of the total protein loss. Mesenteric fat 

 deposits are almost exclusively lipid. 



Glycogen dynamics in both female and male so- 

 matic tissues were insignificant to the mass balance. 

 Data are included here to complete the nutritional 

 energy budget for reproduction. 



Somatic component losses in females in excess of 

 those in males showed 63% was lipid and 35% pro- 

 tein. By converting to energy equivalents (lipid, 9.45 

 kcal/g; protein, 5.65 kcal/g; carbohydrate, 4.10 kcal/g), 

 we determined that 74% of female-specific energy deple- 

 tion was lipid, whereas only 25% was from protein. 



Lipid, protein, and glycogen accumulated in the 

 ovaries during vitellogenesis and gestation with a 

 net gain of 29 g (Table 2). Protein accounted for 21 g 

 and lipid 7 g of the net accumulation. The lipid gained 

 in ovaries represented 43% of the lipid depleted from 

 female soma in excess of male losses. The 21-g gain 

 in ovary protein during ovarian development was a 

 220% net increase relative to female-specific somatic 

 protein loss. Unlike somatic tissue depletion where 

 lipid accounted for the greatest energy loss, protein 

 accretion contributed the greatest amount of energy 



Yellowtail rockfish follow a vi- 

 viparous mode of reproductive 

 development with significant 

 maternal investment (MacFarl- 

 ane et al., 1993). Their repro- 

 ductive strategy provided a 

 model to determine nutritional 

 energy dynamics of female vi- 

 viparous reproduction. Males 

 could be used to estimate adult 

 metabolic maintenance because 

 testicular development and 

 other reproductive functions are 

 quiescent during the period of 

 ovarian growth and somatic re- 

 serve depletion. Moreover, the 

 depletion of somatic reserves 

 was directly reciprocal to ova- 

 rian growth, allowing a more 

 accurate estimation of nutrient 

 mobilization for ovarian development. Consequently, 

 differences between female and male somatic losses 

 reflect costs for female reproduction. Since this spe- 

 cies does not migrate (Carlson and Haight, 1972; 

 Carlson and Barr, 1977; Pearcy, 1992), there is no 

 energy utilization for increased locomotion, as found 

 with anadromous or catadromous fishes. 



In yellowtail rockfish, somatic energy reserves 

 were accumulated in both sexes during the summer 

 and fall and depleted over winter when food avail- 

 ability decreased greatly (Hobson and Chess, 1988; 

 Ainley, 1990). Although female soma gained greater 

 mass than males during the summer, tissue masses 

 were about the same in both sexes at the end of win- 

 ter. Approximately 40% more somatic reserves were 

 depleted from females than from males between Oc- 

 tober or November (maximal somatic mass) and 

 March, or during the period spanning vitellogenesis 

 to parturition. This difference was attributed to uti- 

 lization of these reserves for ovarian development 

 and related reproductive costs. 



The location and quantitative importance of so- 

 matic reserves varies interspecifically in teleosts 

 (Love, 1970; Weatherley and Gill, 1987). Interest- 

 ingly, in yellowtail rockfish, a largely inactive fish, 



