Inter species changes of lipid compositions in liver of shallow-water sharks from the Indian Ocean

Abstract

The liver oils of five dominant shark species, Alopias superciliosus, Carcharhinus falciformis, C. longimanus, Prionace glauca, and Sphyrna lewini, in the Indian Ocean were studied for their lipid classes, fatty acid and triacylglycerol (TAG) molecular compositions, in order to understand and identify the inter species changes and possible utilization avenues. The livers showed 26.1-60.1% oil content regardless of the gender or species of shark. Triacylglycerol was the predominant lipid class (65.2-86.1%) in all species followed by sterol esters (2.9-12.7%), hydrocarbons (2.5-11.6%) and diacylglyceryl ethers (1.0-3.8%). The major fatty acid in total lipid and TAG was docosahexaenoic acid (C22:6n-3; DHA), which in male S. lewini was at remarkable levels (43.4%). The predominant fatty acid combinations of TAG molecules in all shark species were palmitic, DHA and oleic acids (PDO 12.5-19.9%), and palmitic, DHA and palmitic acids (PDP; 8.4-15.4%). Tridocosahexaenoin was found in considerable levels in S. lewini (male).