SEASONAL-VARIATIONS IN FAT-CONTENT AND FATTY-ACID COMPOSITION OF MALEAND FEMALE COREGONID BONDELLA FROM LAKE-MAGGIORE AND LANDLOCKED SHAD FROM LAKE-COME (NORTHERN ITALY)

The Lake Maggiore bondella Coregonus macrophthalmus use perivisceral a dipose tissue for gonadal development (with particular evidence in fem ales), and muscle far as an energy source. Females use mainly saturate d fatty acids (SFA) for energy purposes, while males use monounsaturat es (MUFA) also. During vitellogenesis, females can also mobilize fatty acid precursors of gonadal highly unsaturated fatty acids of the omeg a 3 family from muscle tissue, bur in both sexes specific retention of docosahexaenoic acid (DHA=22:6 omega 3) in muscle is evident. Landloc ked shad, unlike several freshwater fishes, can utilize the liver as w ell as body cavity and muscle as a fat reserve depot. The perivisceral fat stored during the feeding period appears to be utilized mainly fo r winter energy maintenance requirements. Lipid reserves from liver an d muscle are also mobilized to meet the requirements resulting from go nadal development. In particular, females seem to use liver reserves, especially 18:1 omega 9, more than males, to meet the demands of ovoge nesis. In the muscle, SFA are used mainly for energy purposes. During gonadal development, specific muscular and hepatic omega 3 highly unsa turated fatty acids (omega 3 HUFA=20 : 5+22 : 5+22 : 6) and omega 6 HU FA (20 : 4+22 :4+22 : 5) retention is evident in both sexes, while fat ty acid precursors of omega 3 and omega 6 HUFA are mobilized, especial ly from muscle tissue. (C) 1996 The Fisheries Society of the British I sles