Current state of ichthyofauna and use of aquatic bioresources in the Khrystoforivske Reservoir (Bokovenka River, Dnipro basin)

Purpose. To investigate the current state of the ichthyofauna in the Khrystoforivske Reservoir (nearshore and pelagic fish communities), the peculiarities of the distribution of fish communities, their abundance, as well as bioproduction capabilities, the prospects for further fisheries use of the reservoir, considering the ecologically balanced load on the aquatic ecosystem. Methodology. The study on the ichthyofauna was conducted in the Khrystoforivske Reservoir (lower reaches of the Bokovenka River, Dnipro River basin) in July 2022 in nearshore shallow waters and open (deepened) parts of the reservoir. To study pelagic species, gill nets with mesh sizes of 38, 50, 52, 55, and 92 mm were used. Sampling in the nearshore area was carried out with a 15 m long small-mesh beach seine. 504 specimens of fish from gill nets and 208 specimens of fish from beach seine were subjected to biological analysis. Fish age, standard length and individual weight were determined. To assess the dynamics of the state of the ichthyofauna of the Khrystoforivske Reservoir, data from scientific justifications of regime for special commercial fish farms (SCFF) for the period 1996–2022 were used. Findings. The species composition of the ichthyofauna of the Khrystoforivske Reservoir, according to research data of 2022 included 18 fish species. Since 1996, 20 fish species belonging to 6 families were recorded. The composition of nearshore and pelagic fish communities, peculiarities of their distribution, quantitative indicators by species (number and biomass), and age characteristics have been determined. Fish productivity and the stock of aquatic bioresources by species (native and introduced species) were calculated, and ecologically balanced volumes of aquatic bioresource extraction from the reservoir, which operated in the SCCF mode, were recommended. Originality. For the first time, data on the species composition, quantitative parameters of nearshore and pelagic fish communities, distribution and state of the ichthyofauna of the Khrystoforivske Reservoir were analyzed, and the stock and volumes for extraction of aquatic bioresources were calculated. A retrospective description of the ichthyological complex from the reservoir was provided, and the prospects for its further fisheries use were determined. Practical Value. The results obtained are of practical importance for the preparation of scientific and biological justifications for the fisheries use of the Khrystoforivske reservoir on the Bokovenka River (Dnipro River basin). In addition, the study results have a theoretical aspect in determining current changes in the state of ichthyofauna, the further formation of fish communities in reservoir ecosystems, considering the impact of complex human impact.