ELDRIDGE ET AL.: BIOENERGETICS AND GROWTH OF STRIPED BASS 



sue growth and differentiation. These needs re- 

 mained high into the period of feeding transfor- 

 mation and then leveled off to nearly constant 

 rates after D-10. Similar patterns have been seen 

 in other fishes (Smith 1957; Blaxter 1969). The 

 relation of oxygen consumption to weight is usu- 

 ally described in a log-log transformation with a 

 slope approximating 0.8 (Winberg 1956). Our 

 slope of 0.72 shows that our equation describes 

 the weight-metabolism relation up to the final 

 size encountered. Laurence (1977) found winter 

 flounder metabolism profoundly changed after 

 metamorphosis resulting in a curvilinear pat- 

 tern described best by a third degree polynomial 

 equation. It is likely that striped bass would show 

 similar tendencies when measured further along 

 in development. 



Reviews (Blaxter 1969; Eldridge et al. 1977) 

 show that efficiencies during the strictly endoge- 

 nous energy period of embryos and prefeeding 

 larvae ranged from 40% to 70%. Our findings 

 with striped bass tended toward the low side of 

 this range. Micropterus salmoides was most 

 similar to striped bass, with efficiencies of 35.2% 

 to hatching and 43.9% to feeding (Laurence 

 1969). Like those of striped bass, the eggs of M. 

 salmoides also possess large oil globules, and 

 their larvae have similar predatory behavior. 

 Gross growth efficiencies of aquatic consumers 

 in general normally fluctuate between 15% and 

 35% (Welch 1968). Efficiencies of larval and post- 

 larval fishes have also been found to be within 

 this range (Ivlev 1939a; Laurence 1973, 1977). 

 Ivlev (1945) believed postembryonic stages were 

 restricted to efficiencies <35%, and fish nor- 

 mally have decreasing efficiencies with age 

 (Parker and Larkin 1959; Theilacker footnote 4). 

 All our efficiency values support these conclu- 

 sions. Whether feeding or not, our older larvae 

 had lower conversion efficiencies, probably re- 

 sulting from increased metabolic demands asso- 

 ciated with greater activity. 



All organisms must balance input and output 

 energies to successfully survive, grow, and ulti- 

 mately reproduce. The essential relations 

 between input and output energies and the equa- 

 tion which balances them have been well dis- 

 cussed by several authors (Winberg 1956; War- 

 ren and Davis 1967; Warren 1971; Wiegert 

 1976). This paper presents data that make up the 

 basic parameters of an energy budget. The basic 

 relation of these components can be presented in: 



where Qi = input energies, whether endoge- 

 nous, exogenous, or a combina- 

 tion of the two 

 Qw = waste energy 

 Qa — growth energy 

 Qm = metabolic energy. 



All but Qw have been studied by us, and the 

 effects of food density and initial egg size have 

 been discussed. In Figure 9 we present a graphic- 

 model of the energy budget of striped bass em- 

 bryos and larvae fed the high ration diet (5.0 

 Artemia/mX). This model approximates that of 

 Laurence (1977) except that we include input 

 energies of yolk and oil, and we present the rela- 

 tions against time as rates (i.e., calories con- 

 sumed or expended per 24 h period per organ- 

 ism). 



When the energy budget is presented in these 

 terms, some distinctive patterns emerge. Yolk 

 provides a constant energy input until it is ex- 

 hausted on or about D-7. Oil is used rapidly at 

 first, then more slowly until yolk energy is no 

 longer available and the animal initiates feed- 

 ing. At this time, the larva increases its use of oil 



10 



< 10 

 o 



< 



O 

 > 



D 



Z 



*/» 



— 

 cc 



o 



t o.i 



\ \ 

 A S 



vcar 



• Yolk 



I 



i 

 _1_ 



T" 



6 12 18 24 



DAYS AFTER FERTILIZATION 



30 



Qi = Qw+Q G + Q 



M 



Figure 9.— Energy budget of input calories (yolk, oil. and food) 

 and output calories (growth, metabolism, and nonassimilation) 

 presented in calories per individual embryo or larva per day. 



471 



