STATUS OF THE STERLET ACIPENSER RUTHENUS LINNAEUS, 1758 POPULATION AND REPRODUCTION IN THE LOWER DON RIVER BASIN

Background. Before the construction of dams and hydrotechnical structures, sterlet was a commercially valuable species, widespread in the Don River Basin. Due to the river regulation and changes in the hydrological conditions influencing the natural spawning process, the sterlet population abundance in the Don River had decreased so much that this species was included in the Red Book of the Russian Federation, as well as regional Red Books. Relevance. The status of the sterlet population in the Don River remains insufficiently studied, despite the measures taken for its artificial reproduction and the constant increase in the number of released juveniles. The aimof this study is to analyze the status of the sterlet population in the Don River and to assess the effectiveness of the measures for its artificial reproduction in the modern period. Methods. The analysis of the current state of the sterlet population was based on the statistical data on the number of its juveniles released by hatcheries into the Don River, information on the number of the mature sterlet individuals transferred through the fish-lifting lock (FLL) of the Kochetovsky Hydrotechnical System, as well as the data collected during field research. Results. The effectiveness of the measures aimed at facilitation of the sterlet artificial reproduction in the Lower Don Basin has been assessed, and the necessity of expanding the research into the current state of the sterlet population to alter its conservation status has been indicated. Conclusion. The observed trend for the increase in the sterlet abundance in the Lower Don following the sizable releases of its juveniles by hatcheries in the last decade provides the basis for removal of this species from the Red Book of the Russian Federation and the Red Book of the Rostov Region.