Study on lipid accumulation and contribution to reproductive energy in female Illex argentinus

To explore the accumulation of tissue lipid and its contribution to reproductive energy during gonadal development of Illex argentinus has important theoretical value for understanding its reproductive investment strategy, as well as the sustainable development and utilization of this resource. By using tissue energy density measurement technology and lipid extraction technology, we measured and analyzed the energy density of mantle soma, digestive gland, ovary and oviduct eggs of female I. argentinus before and after degreasing, as well as the lipid mass fraction, lipid energy and proportion of each tissue. Results indicate that the energy density of all tissues decreased significantly after lipid extraction. During the maturation, female I. argentinus maintained a relative stable level of the lipid mass fraction and percentage of lipid energy in mantle soma and oviduct eggs. However, there was a significant decreasing trend in the lipid mass fraction and percentage of lipid energy in the digestive gland but an increasing trend in the ovary (Maximum in Phase IV) along with maturation. Furthermore, Pearson's r analysis indicates that there was a significantly negative relationship in the lipid mass fraction, lipid energy and percentage of lipid energy between gonadal tissues (Combination of ovary and oviduct eggs) and digestive gland, but without a significant relationship between gonadal tissues and mantle soma. In summary, female I. argentinus exhibits tissue-specific lipid content and lipid energy accumulation. The lipid content has a significant contribution to the reproductive energy, and lipids in the gonadal tissues are significantly correlated with lipids in the digestive gland, which further proves that energy allocation to reproduction in I. argentinus mainly depends on the income resources.