Abstract:Argentinean short-fin squid, Illex argentinus, is an important Cephalopod species, characterized by fast growth, short lifespan and semelparous reproduction. It has been assumed that the stock biomass is closely related to the nutrients acquisition, accumulation and subsequent allocation to reproduction during the sexual maturation. In order to understand the fatty acid composition and its changes during sexual maturation in female Illex argentinus, the fatty acid profiles and their relative content in multiple tissues, namely mantle tissue, digestive gland and ovary, were investigated by the methods of chloroform-methanol and gas chromatography. The results indicated that the polyunsaturated fatty acids (PUFA) were the most abundant fatty acid class for the tissues investigated, followed by saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). A total of 28 fatty acid profiles were detected in mantle tissue, while digestive gland and ovary were had 21 fatty acid profiless and 17 fatty acid profiles, respectively. It was found that most of SFA content was presented as C16:0, MUFA content as C18:1n9c and C20:1, and PUFA content as docosahexaenoic acid (DHA; 22:6n3) and eicosapentaenoic acid (EPA; 20:5n3). During the sexual maturation, both SFA content and MUFA content in mantle tissue attained the highest level at mature stage, and then decreased significantly at spawning stage, probably indicating these fatty acids were mobilized to fuel reproduction. PUFA content in digestive gland was significantly lower than that in mantle tissue or ovary, even though it maintained a relatively stable status throughout sexual maturation. The ovary continuously accumulated fatty acid content, but showed a significant decrease in MUFA content and PUFA content during the spawning period, possibly suggesting that these fatty acids were increasingly allocated to oogenesis. These evidence indicated that the fatty acid profiles in Illex argentinus showed tissue-specific characteristics, while the major fatty acid profiles were consistent in mantle tissue, digestive gland and ovary. In the mantle tissue, both SFA and MUFA were possibly mobilized to fuel reproductive growth during sexual maturation. In the digestive gland, the PUFA content might be continuously transferred to mantle and ovary with maturation. Regarding fatty acids in the ovary, the content might be continuously accumulated and subsequently used to support oogenesis during the sexual maturation.
