Response of striped bass larvae fed brine shrimp from different sources containing different fatty acid compositions

Abstract

Nauplii from five sources of brine shrimp ( Artemia sp.) were evaluated for total lipid and fatty acid compositions and subsequently fed to larvae of striped bass, Morone saxatilis. Chinese (CH) and a San Francisco Bay (SFBa) sources were relatively high in 20:5 ( n−3), eicosapentaenoic acid (EPA), containing 10.4 and 9.3% (of the lipid), and relatively low in 18:3 ( n−3), linolenic acid, containing 3.6 and 3.8%, respectively. Sources from Great Salt Lake (GSL), Colombia (COL), and a second San Francisco Bay source (SFBb) were lower in EPA, containing 1.2, 3.0, and 1.2% and higher in linolenic acid, containing 28.2, 24.2, and 25.2%, than the CH and SFBa sources. Docosahexaenoic acid (DHA), 22:6 ( n−3), was not found in any of the brine shrimp. Percentages of total lipids, triacylglycerols, and free fatty acids, were not significantly different among the source.s The larvae were fed nauplii from the five sources of brine shrimp as the first and only food for 12 days (experiment 1) or 17 days (experiment 2). Growth and survival were significantly higher for the larvae fed brine shrimp containing the higher levels of EPA. The slower growth and lower survival of larvae fed brine shrimp high in linolenic acid and low in EPA suggested that striped bass are not capable of elongating and desaturating linolenic acid to longer chain n−3 highly unsaturated fatty acids. These results indicate that striped bass larvae have a dietary requirement for EPA which is in excess of 3% of the dietary lipid or 0.5% of the dry diet, and that variation in EPA content is a major reason for the variation in nutritional quality among brine shrimp sources.