ELDRIDGE ET AL.: BIOENERGETICS AND GROWTH OF STRIPED BASS 



on diel feeding patterns and evacuation rates of 

 larvae in our experimental systems were con- 

 ducted in the early stages of this study and were 

 presented in Eldridge et al. (1981). Because lar- 

 vae in all food concentrations consumed their 

 food within 10 h after food was first introduced, 

 we selected 10 h/d for use in the above formula. 

 We found that sampling larval stomachs 1 h 

 after food introduction was most representative 

 of average stomach contents during the active 

 feeding periods. A minimum of 10 larvae was 

 dissected and the stomach contents were quanti- 

 fied for each food ration estimate for each experi- 

 ment. Evacuation rates of food ingested by lar- 

 vae which were feeding continuously ranged 

 from 1 .5 to 5.5 h with an overall average of 3.3 h. 

 Times of 100% evacuation were combined for dif- 

 ferent-aged larvae and used in this study (Table 

 1). 



Table 1.— Average times (h) required for Ar- 

 temia nauplii to pass through the digestive 

 tracts of continuously feeding striped bass lar- 



Energy Output Determinations 



Growth of embryos and larvae was measured 

 by carefully removing all yolk and oil globules 

 from Formalin-preserved specimens, rinsing 

 the remaining tissues in distilled water, drying 

 at 60°C, and weighing to the nearest 0. 1 ng. Mea- 

 surements were in duplicate with 3 to 5 speci- 



mens per sample. Standard lengths of larvae 

 were measured to the nearest 0.1 mm with an 

 ocular micrometer. Duplicate measurements of 

 20 larvae each were done. Preserved specimens 

 were measured as soon as possible. The entire set 

 of samples from each experiment required an 

 average of 8 wk to process. 



Oxygen consumption was used as a measure of 

 "routine" metabolism (Fry 1971) and was mea- 

 sured with standard manometric techniques 

 using a differential microrespirometer. At least 

 five replicate samples (from 5 to 50 animals/sam- 

 ple depending on age and size) were taken at 

 each test period. Sampling occurred at D-0.5, 

 -1.0, -2.0, -4.0, and on each even day until D-30 

 (time measured from time of fertilization). 



RESULTS 



Energy Inputs 



Endogenous Sources 



Initial sources of energy for striped bass em- 

 bryos and early larvae are yolk and oil, the latter 

 contained in a single large globule. The relative 

 composition of these egg components was found 

 to vary considerably between the seven different 

 females used in rearing experiments (Table 2). 

 Oil accounts for most of the variability in dry 

 weight, whereas yolk is more variable in mea- 

 surements of volume. Caloric contents of these 

 two energy sources were consistent, which indi- 

 cates that variability of total energy in the egg 

 results from differences in absolute amounts of 

 oil, yolk, or both, rather than differences in the 

 energy content of those materials. Eggs from 

 different females contained widely ranging 



Table 2.— Dry weights, volumes, and caloric contents of striped bass eggs and egg components at time of fertilization. 

 Three replicates of 25 eggs each were used for dry weights, three replicates of 20 eggs each for volumes, and two replicates 

 of approximately 50 mg (dry weight) were used for caloric content determinations. 



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