Diet-induced changes in fatty acid composition of herring larvae reared in enclosed ecosystems

Fertilized herring eggs were hatched in large sea water enclosures containing natural populations of phytoplankton and Zooplankton and the developing fish sampled at intervals for a period of 90 days to determine the levels and composition of their depot triacylglycerols. The percentage of triacylglycerols in total lipid declined from hatching to about 40 days post-hatch and then increased markedly during the remaining 50 days. During the first 30 days from hatching the acyl groups of the triacylglycerols were dominated by polyunsaturated fatty acids, especially 18:4 ( n −3), 20:5 ( n −3) and 22:6 ( n −3), characteristic of a predominantly phytoplanktonic diet. For the remainder of the 90-day experiment the percentages of polyunsaturated fatty acids decreased, to be replaced by increasing percentages of 20:1 ( n −9) and 22:1 ( n −11 ) fatty acids characteristic of a predominantly zooplanktonic diet.