Effect of spawning fast on lipid and fatty acid composition of eggs of captive turbot ( Scophthalmus maximus L.)

Abstract

Total, neutral and phospholipid levels were determined in cultivated turbot eggs from the beginning, middle and end of the spawning seasons of three females in order to assess if the spawning fast of mature females affects the lipid composition of eggs produced late in the season. Dry weight measurements and fatty acid analyses were also carried out. There were no obvious variations in water content or in the percentage concentrations of neutral or phospholipids in early- and late-season eggs. Percentage dry weight of total lipid increased slightly in each female's late-season eggs, but only significantly so in those from one female ( P<0.05). However, the weight of total lipid per egg fell as the spawning season progressed because of a seasonal decline in egg size. There were significant increases in the levels of 18:3 n−3 ( P<0.05), 22:4 n−6 ( P<0.01) and 22:5 n−3 ( P<0.01) in the neutral lipid fraction of late-season eggs compared to early-season eggs. However, neutral 20:5 n−3 and 22:6 n−3 levels remained fairly constant throughout the season. Percentage concentrations of phospholipid 20:5 n−3 showed a significant decrease ( P<0.05) in late-season eggs, and levels of phospholipid 22:5 n−3 and 22:6 n−3 decreased in later egg batches, though not significantly. Experiments comparing the growth and survival of early- and late-season larvae produced by the same three turbot suggest that early-season larvae do not outperform their late-season counterparts under hatchery conditions.