Diet-egg relationships and equilibration of fatty acids in eggs of southern flounder, Paralichthys lethostigma

There is increasing interest in the transfer of nutrients from broodstock diets to eggs due to the consequences for egg and larval quality. Analyses were conducted with southern flounder Paralichthys lethostigma to identify which fatty acids (FAs) in eggs are influenced by broodstock diet and how long it takes for the FA composition of eggs to equilibrate to the broodstock diet. Data were obtained from a laboratory experiment and from hatchery production operations. For each source, two populations of adult flounder were given one or the other of two diet treatments. In the laboratory experiment, the diets differed markedly in FA composition. In the hatchery, a base diet was supplemented on two different schedules. Each of the four diet treatments produced eggs with significantly different mean FA compositions. Of the 27 FAs measured, 19 differed significantly between diets and had corresponding significant differences in eggs (direct diet-egg relationships). Combining results with data from a prior study showed that equilibration of eggs to a change in adult diet takes 8-16 weeks for southern flounder. These findings will be useful for improving broodstock diets and feeding protocols for captive flounder being used by stock-enhancement programs that are designed to mitigate the long-term and widespread population declines of this species.

Automated summary

This study investigated the transfer of fatty acids from broodstock diets to eggs and the time needed for the eggs to equilibrate to the diet in Southern flounder. The findings indicate that different diet treatments significantly affect the fatty acid composition of eggs, and it takes 8-16 weeks for the eggs to adapt to changes in the adult diet. These results are important for improving broodstock diets and feeding protocols in stock-enhancement programs.