Seasonal cycles in total chemical composition of two Lake Baikal benthic‐pelagic sculpins (Cottocomephorus, Cottoidei)

Abstract

Annual cycles in chemical composition of the body, liver, gonads, red and white muscles were determined for two medium fat sculpins, Cottocomephorus grewingki and C. inermis, endemic to Lake Baikal. Their total lipid content ranged from 3 to 9% during the year. The content of defatted dry substance was 14–17%, similar to the protein content of the other Baikalian cottoid fishes. The prespawning period was characterized by a positive lipid and protein balance in both species. In C. grewingki the liver performed largely a metabolic function, whereas in C. inermis it served also as a storage site for lipid reserves. During spawning, total body lipids of females of both species showed a two‐ to threefold decrease. Males of C. grewingki guarding nests deplete greatly their total body lipids, which decrease seven‐ to ninefold by the time of larval hatching in comparison with the prespawning period, and constitute 1–2%. After spawning, lipid reserves of C. grewingki were quickly restored to the initial level (from about 3 to 9%) and maintained during the long sexual maturation period. In C. inermis total body lipids increased only twofold in comparison to those observed during the spawning period.