Maternal Allocation of Lipids to Eggs by Southern Flounder after Diet Changes

Abstract

AbstractMaturation and spawning diets for flatfish broodstock, such as Southern Flounder Paralichthys lethostigma, have received little research attention, despite their critical role in the reproductive performance. During the spawning season, which is when Southern Flounder broodstock produce multiple egg batches, they rely on their diet to supply nutrients to the eggs. Lipids are an important class of nutrients for offspring development. The objective of this brief communication is to describe the changes in egg lipid classes during the spawning season following a diet change. Female broodstock were fed three diets after the first spawn (week 0)—a control diet (equal weights of Spanish Sardines Sardinella aurita and brown shrimp Farfantepenaeus aztecus), a shrimp‐only diet, and a sardine‐only diet (n = 3, 3, and 4, respectively)—for a period of 6 weeks and the lipid composition of the eggs was measured every 2 weeks. The change to a diet of sardines only or shrimp only altered the concentrations of egg lipid classes, indicating that egg composition is affected by maternal dietary intake over a period of 2 weeks or less. Females that were fed the sardine‐only diet produced eggs with higher levels of ketones and acetone‐mobile polar lipids and lower levels of hydrocarbons than did females that were fed shrimp, exhibiting changes that were consistent with the differences between the diets. The shift to the sardine‐only diet had little effect on total lipids, triacylglycerols, free fatty acids, and sterols in the eggs. The change to the shrimp‐only diet resulted in subtle but consistent decreases in all of the lipids, except wax/steryl esters at week 2, followed by gradual increases. This suggests that the shrimp‐only diet provided insufficient nutrition and that the females mobilized stored lipids to compensate. These preliminary results revealed interesting patterns that, with further research, could lead to improved diets and feeding protocols for the production of Southern Flounder.