Effects of Temperature on Growth and Biochemical Composition of Larval Winter Flounder Pseudopleuronectes americanus

Winter flounder (Pseudopleuronectes americanus) eggs fertilized at 2 'C were incubated at 2, 5, 7, and 10 "C. At hatching the larvae produced at all 4 temperatures were similar In standard length, protein, RNA and DNA content, although differences between groups were apparent at completion of yolk absorption. Larvae held at 2 'C never fed. Increased mortality in this group began shortly before hatching and continued until complete mortality occurred o n Day 21. Larvae held a t 5 "C began feeding on the day of completion of yolk absorption. Larvae held a t 7 and 10 ' C began feeding 1 and 2 d after yolk absorption, respectively. The poor condition of first feeding larvae a t 10 "C was indicated by their low RNA content and low RNA-DNA ratio. A positive linear relation between RNA-DNA ratio and growth rate was observed at 5, 7, and 10 "C. The effect of temperature on the RNA-DNA ratio-growth relation is described.