Whitefish varieties are valuable fishing grounds that constitute an important resource in the Arctic and Subarctic water bodies of Russia, and some of them (pelyad, muksun, and some others) are endemic species to our country.
Whitefish stocks have been steadily declining due to high commercial value and excessive fish harvesting pressure. Natural factors, especially in the embryonic and early postembryonic periods, may also be the reasons for the decrease in their numbers: water temperature, siltation of spawning grounds, illumination, pH, etc. [14]. Poaching and oil and gas development of the Northern territories are most important anthropogenic factors reducing the stocks of these species. Thus, as a result of the influence of several negative factors, the volume of the total average annual catch of Muksun from the Arctic coast of Siberia has diminished by half since the second half of the XX century – from 20 to 10 thousand centners. As of today, Muksun is listed in the Yamal Red Book, and its harvesting has been banned since 2014. The abundance of the Broad Whitefish populations on the Arctic coast of Siberia can be considered satisfactory, but the number of whitefish in the Ob River has decreased sixfold in 30 years [1]. Also, after the introduction of restrictions for capturing Muksun, the fishing pressure on the Broad Whitefish population increased, which will inevitably lead to a critical drop in its stocks.
Under the conditions of long-lasting pollution of lake-river systems in the North of Western Siberia, the natural mechanisms of auto-rehabilitation in whitefish were suppressed, which was caused by the long-term accumulation of toxic substances leading to the development of pathologies [6, 7]. An increase in chromosomal mutability of Muksun and Pelyad from the Ob-Irtysh basin [3] leads to the accumulation of cytomorphological disorders, accompanied by deformities and death of juveniles in the postembryonic period. Accordingly, this transmutes into the degradation of gene pools, an increase in the risk of loss of genetic resources, and a decrease in population and abundance of species.