Seasonal variations in fat content and fatty acid composition of male and female coregonid‘ bondella’ from Lake Maggiore and landlocked shad from Lake Como (Northern Italy)

The Lake Maggiore bondella Coregonus macrophthalmus use perivisceral adipose tissue for gonadal development (with particular evidence in females), and muscle fat as an energy source. Females use mainly saturated fatty acids (SFA) for energy purposes, while males use monounsaturates (MUFA) also. During vitellogenesis, females can also mobilize fatty acid precursors of gonadal highly unsaturated fatty acids of the ω3 family from muscle tissue, but in both sexes specific retention of docosahexaenoic acid (DHA=22: 6ω3) in muscle is evident. Landlocked shad, unlike several freshwater fishes, can utilize the liver as well as body cavity and muscle as a fat reserve depot. The perivisceral fat stored during the feeding period appears to be utilized mainly for winter energy maintenance requirements. Lipid reserves from liver and muscle are also mobilized to meet the requirements resulting from gonadal development. In particular, females seem to use liver reserves, especially 18: 1ω9, more than males, to meet the demands of ovogenesis. In the muscle, SFA are used mainly for energy purposes. During gonadal development, specific muscular and hepatic ω3 highly unsaturated fatty acids (ω3 HUFA=20: 5 + 22: 5 + 22: 6) and ω6 HUFA (20: 4+22: 4+22: 5) retention is evident in both sexes, while fatty acid precursors of ω3 and ω6 HUFA are mobilized, especially from muscle tissue.