Lipid class and fatty acid composition of liver of firefly squid Watasenia scintillans

The lipid content and composition of the liver of firefly squid Watasenia scintillans from the Sea of Japan were investigated. The amount of liver lipids of firefly squid increased from March to April and then decreased in May or June. From March to July the liver of firefly squid from Toyama Bay contained a larger amount of lipids than that from Wakasa Bay. The liver lipids of firefly squid were characterized by high levels of triglycerides (60.9-72.7%) with small amounts of other components. The lipid class composition was more or less constant in spite of the differences in the fishing ground and season. The component fatty acids of liver lipids consisted of saturates (22.4-26.4%), monoenes (37.5-45.6%), and polyenes (29.9-37.8%). The major fatty acids were palmitic (13.6-16.3%), palmitoleic (6.5-9.2%), oleic (16.3-21.5%), eicosenoic (5.3-9.3%), eicosapentaenoic (13.0-20.0%), and docosahexaenoic (7.6-12.3%) acids. Firefly squid from Toyama Bay contained higher percentages of eicosapentaenoic acid than that from Wakasa Bay. The seasonal change in the eicosapentaenoic acid level was coincident with that of the lipid contents in the liver.