Первые сведения о биологии сибирской ряпушки Coregonus sardinella Курейского водохранилища

Abstract

Nine large hydroelectric power plants have been put into operation within the Yenisey River basin, with two of them, Kureyskaya and Ust-Khantayskaya, located beyond the Arctic Circle. The Kureyskoye reservoir is a canyon-type reservoir with low temperatures, high flow rate and a distinctive oxygen regime. The main objective of this work is to perform stock assessment of the least cisco near the dam of the Kureyskoye Reservoir. In this research, biological stock characteristics of least cisco at the early stages of growth are presented for the first time. A sample of 199 individuals of least cisco was used. Fish were collected in July 2013, and in October-November 2016, 2018, 2019 in the water intake of the Kureyskaya dam, located in the southwestern part of the Kureyskoye Reservoir. The following stock characteristics were studied for the captured least cisco individuals: total length (TL, mm), fork length (FL, mm), standard length (SL, mm), body weight (W, g), sex, age of maturity. To determine the age of the fish, scales were used, selected on the part of the body between the lateral line and the dorsal fin, to count the number of sclerites in the annual rings. Individual absolute (IAF) and relative fertility (IRF) were evaluated by the volume-weight method for 20 females captured in 2019. The results of determining the age of fish were used to calculate the parameters of the von Bertalanfi growth equation. All statistical calculations were carried out in the R 4.2.3 environment using the FSA package (Ogle, 2016). The asymptotic length (FLinf), calculated with the von Bertalanfi equation, is 177.08±2.18, K (growth rate) = 1.19±0.14; t0 = 0.22±0.07. The studied least cisco becomes sexually mature at the age of 4.37±0.69 years. The individual absolute fertility (IAF) of the least cisco varies between 3031-7244 eggs, for which the mean is 5369±1007. Individual relative (IRF) fertility varies from 59 to 117, on average 89 ± 15 eggs per 1 g of female weight. Thus, the modern population of least cisco in the Kureyskoye Reservoir is characterized by a lower growth rate than in similar reservoirs, and in comparison with river forms. The existing growth rate makes it possible for fish to potentially reach sizes up to 17 cm, but the real population is mainly represented by fish of small size groups. Fertility indicators are within the limits for similar populations of the Siberian canyon-type reservoirs.