Lipid accumulation and fatty acid composition during maturation of three pelagic fish species in Lake Baikal

In August and September of 1993, samples were collected from Lake Baikal, Russia to examine the lipid composition of major fauna including phytoplankton, zooplankton, benthic amphipods, and individual year classes of the three major pelagic fish species: Comephorus dybowskii, Comephorus baicalensis, and Coregonus autumnalis migratorius (omul). Total lipid content of all fish samples ranged from 7.8 to 345.1 (mg/g wet weight). Lipid class and fatty acid composition showed significant shifts with increasing age in fish. Lipid content in adult Comephorus baicalensis showed the greatest change, with total lipids increasing front 1.63% of wet weight in juveniles (3 yr.) individuals to over 30% in mature adults (8-10 year). Triacylglycerol was the primary lipid store, increasing from 18 to over 90% of total lipids in several year classes of C, baicalensis with lesser amounts in C. dybowskii and omul. Three fatty acids, the 16:0, 18:1(9), and 22:6 were the major fatty acids in all fish, with significant shifts in distribution attributable to changes in prey items during fish maturity. Cholest-5-en-3 beta-ol (cholesterol) was the dominant sterol in all fish (> 99% of total sterols) and did not show any significant difference among species or with maturity. Carbon and nitrogen isotopic signatures of animal tissue and total lipids varied with age, but provided no set pattern. Results of lipid class and fatty acid composition analysis demonstrated changes in diet and energy storage during maturation of all the three major fish species.