LIPID-ACCUMULATION AND FATTY-ACID COMPOSITION DURING MATURATION OF 3 PELAGIC FISH SPECIES IN LAKE BAIKAL

In August and September of 1993, samples were collected from Lake Baik al, Russia to examine the lipid composition of major fauna including p hytoplankton, zooplankton, benthic amphipods, and individual year clas ses of the three major pelagic fish species: Comephorus dybowskii, Com ephorus baicalensis, and Coregonus autumnalis migratorius (omul). Tota l 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 sh ifts with increasing age in fish. Lipid content in adult Comephorus ba icalensis showed the greatest change, with total lipids increasing fro nt 1.63% of wet weight in juveniles (3 yr.) individuals to over 30% in mature adults (8-10 year). Triacylglycerol was the primary lipid stor e, increasing from 18 to over 90% of total lipids in several year clas ses of C, baicalensis with lesser amounts in C. dybowskii and omul. Th ree fatty acids, the 16:0, 18:1(9), and 22:6 were the major fatty acid s in all fish, with significant shifts in distribution attributable to changes in prey items during fish maturity. Cholest-5-en-3 beta-ol (c holesterol) was the dominant sterol in all fish (> 99% of total sterol s) and did not show any significant difference among species or with m aturity. 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 i n diet and energy storage during maturation of all the three major fis h species.