Selective retention and transfer of long-chain polyunsaturated fatty acids in Japanese sardine

Essential fatty acids are suggested to be key elements in trophodynamic processes in small pelagic fish. Small pelagic fish generally acquire these fatty acids from phytoplankton and zooplankton lipids; however, little is known about the utilization characteristics of fatty acids. To clarify this, we measured the fatty acid composition of Japanese sardine, Sardinops melanostictus , during the feeding and spawning periods. A comparison of fatty acid composition between sardine and zooplankton in the feeding period indicated that sardine preferentially retained high levels of specific long-chain polyunsaturated fatty acids (LC-PUFAs), such as docosahexaenoic acid (DHA) and arachidonic acid, in the muscles compared to those in dietary organisms. Further, a comparison of sardines between the feeding and spawning periods demonstrated that the levels of these LC-PUFAs in the muscle decreased during the spawning period. Instead, the levels of LC-PUFAs in the ovary (especially DHA) increased with ovary-somatic development, indicating that in the sardine, these LC-PUFAs are transferred from the muscle to the gonad during the spawning period.