Biological indicators of coregonid fish species in lake Tulos (Western Karelia)

Coregonid fish are valuable commercial species in northern freshwater ecosystems. The relevance of the work is determined by the decrease in their stocks as a result of human activities. The aim of the study was to study the biology of coregonid species in Lake Tulos (Republic of Karelia) and assess the lake in terms of its fisheries management. The assessment of the lake ecosystem is given. It is shown that the reservoir belongs to the alpha-oligotrophic type. The fish population of the lake is represented by 14 species. The paper presents the data on the state of coregonid species in the water body. The fish of the family Coregonidae in Lake Tulos are represented by European vendace Coregonus albula and whitefish C. lavaretus. The vendace of Lake Tulos belongs to the small form, with the growth rate close to that of the small forms from other lakes in Karelia. In terms of the number of gill rakers, two ecological forms of whitefish inhabit the lake: a medium-rakered form (29-37 rakers) and a densely rakered form (47-60 rakers). The fishes differ significantly by all biological indicators. It is noted that the complexity of the ichthyofauna of northern ecosystems is achieved not only by the number of species, but also by the abundance of various ecological forms. To preserve the species diversity of this water body fish population it is advisable to introduce regulated fishing on it.