Comparative Analysis of Population Parameters of the Vendace Coregonus albula (Salmonidae: Coregoninae) in Lake Samozero in Different Habitat Conditions

The results of long-term studies of the dynamics of population parameters of the vendace Coregonus albula in Lake Syamozero in periods with different habitat conditions are presented. The vendace is the most abundant fish species in the lake and was the main object of commercial fishing for 39 years (1932-1970) (60% of the total catch). From 1971 until 2000, the input of nutrients into the lake increased significantly due to high human economic activity in the catchment area. This led to a change in the hydrochemical and hydrobiological regimes of the lake. As a result, favorable conditions were created for vendace feeding. The biomass of zooplankton which is the main component of its diet, increased fivefold from 1950 to 2000 (from 0.4 to 2.1 g/m(3)). However, the conditions of reproduction of vendace significantly worsened due to siltation of spawning grounds, which led to the mortality of eggs during a long period of its embryogenesis (6-7 months). The decrease in the vendace abundance in 1971-2000 was also caused by the accidental penetration of a new species, the European smelt Osmeruseperlanus into the lake. For a long time (about 15 years) vendace was not found either in catches or in the diet of predatory fish species of the lake. In recent years, as a result of a decrease in the impact of human activity on the lake and the disappearance of the smelt in 2015 due to its infection with the parasite, the vendace population has begun to recover.