ELDRIDGE ET AL.: BIOENERGETICS AND GROWTH OF STRIPED BASS 



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O 



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I 



10 15 20 25 



DAYS AFTER FERTILIZATION 



30 



Figure 4.— Growth of four batches of feeding striped bass lar- 

 vae measured in calories of assimilated tissue from first feed- 

 ing (D-7) to D-29. 



tial for all fish groups (Fig. 7). Experiment 7 lar- 

 vae were the heaviest per unit length and did nut 

 attain the lengths that other larvae did. All lar- 

 vae put on weight rapidly after reaching a stan- 

 dard length of about 8 mm. 



Oxygen Consumption 



Metabolic rates of embryos and larvae are pre- 

 sented in Figure 8. Embryos and prefeeding lar- 

 vae had the highest Qo 2 's. After feeding began 

 oxygen consumption stabilized and remained 

 constant for the duration of the experimental 

 period. On a weight-specific basis oxygen con- 

 sumption increased with tissue dry weight and 

 was best described by a power function (Fig. 8), 

 although the relationship appears almost linear. 



o 



z 



< 



o 



z 

 < 



12-, 



10- 



6- 



10 15 20 25 



DAYS AFTER FERTILIZATION 



30 



Figure 5.— Growth of four batches of feeding striped bass lar- 

 vae measured in standard lengths from first feeding (D-7) to 

 D-29. 



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0.15 



O- 0.10- 



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005 





-i ' 1 



0.5 



1.0 



FOOD CONCENTRATION NUMBERS (ml" 1 ) 



Figure 6.— Instantaneous growth coefficients of four batches 

 of feeding striped bass larvae that fed on six different food 

 concentrations (0.00 to 5.00 Artemia/m\). 



Utilization Efficiency 



Gross caloric conversion efficiencies were 

 highest from fertilization to initial feeding, fol- 

 lowed closely by efficiencies during the embry- 

 onic period (Table 6). Only in larvae from the 

 highest food concentration did conversion effi- 

 ciencies remain at elevated levels. Larvae feed- 

 ing at the other food concentrations used their 

 resources at levels under 20%, and their conver- 

 sion efficiencies did not appear to correlate with 

 food concentration. Starved larvae had the low- 

 est efficiency and demonstrated negligible 

 growth after D-7. 



Table 6. — Mean gross caloric conversion efficiencies (in per- 

 cent) for striped bass embryos, prefeeding larvae, and larvae 

 feeding at different prey concentrations. 



DISCUSSION 



Energy Inputs 



Striped bass eggs were found to be high in 

 energy content and to vary considerably in size. 

 Undoubtedly the high proportion of lipids (found 

 mostly in the oil globule) makes the striped bass 

 egg one of the most energy-rich of fish eggs. At 

 7,808 cal/g striped bass eggs exceed the caloric 

 values of eggs from freshwater, anadromous, 

 and marine fishes which normally range from 

 5,386 to 6,238 cal/g (Hayes 1949; Smith 1957, 



467 



