Ecosystem of Lake Urozero and results of introduction of new fish species into the water body.
Data on hydrology, hydrochemistry, and hydrobiology, including the fish population, of Lake Urozero (southern Karelia) are given. The results of the work on the introduction of two fish species carried out in Lake Urozero for improving the quality of the ichthyofauna have been analyzed. In the 1950s-1990s, the whitefish Coregonus lavaretus and the European vendace C. albula were repeatedly introduced into the lake. Of the two species, only vendace has become naturalized in the lake. Its biological features in the new habitat conditions have been studied. A comparative analysis of linear-weight parameters with characteristics of the vendace from the donor reservoirs has been carried out. The results make it possible to classify the vendace of Lake Urozero as a large-sized form. Whitefish has not naturalized, which may be due to the small volume of its introduced stocking material and weak viability of the introducing material. Currently, eight species of fish live in the lake. Perch Perca fluviatilis and vendace prevail in abundance. Biological parameters of perch are presented. Currently, vendace constitutes a significant portion in the diet of large-sized perch.