Effects of dietary docosahexaenoic acid enrichment in Artemia feed on the growth, survival, and fatty acid composition of Pacific cod (Gadus macrocephalus) larvae

Optimal larviculture techniques have yet to be established for Pacific cod (Gadus macrocephalus), particularly in relation to the nutritional quality of live prey. Elevated mortality during early life stages is a major concern during the production of Pacific cod larvae; this seems to be related to, among other things, nutritional deficiency during the early feeding stage, particularly the quantities and proportions of highly unsaturated fatty acids in live food. With the aim of improving the growth and survival of larval Pacific cod while also determining the optimum level of dietary docosahexaenoic acid (DHA), we investigated the effects of four levels of dietary DHA (0%, 3%, 6%, and 9% of total fatty acids [TFAs]) on the growth, survival, and tissue fatty composition of larvae. The actual DHA concentrations of the diets were 0.22%, 3.09%, 5.88%, and 9.28% of TFAs for D1, D2, D3, and D4 diets respectively. From 43 to 64 days post hatch, larvae were fed the experimental diets. Larvae fed D3 diet had the highest survival rates, total length, and total weight at the end of the feeding trial. The fatty acid composition of the whole larval body reflected the corresponding dietary composition. Overall, these results suggest that a DHA level of 4.85%-8.50% of TFAs is optimal in the diet of larval Pacific cod during Artemia feeding.