Current structure of commercial catches of the Kyiv Reservoir

Purpose. Determination of current structural characteristics of catches of the main fishing gears used in the Kyiv Reservoir as an element of assessing the distribution of the actual fishing pressure and obtaining initial data for fishery management. Methodology. Ichthyological material was collected from commercial catches of gillnets with a mesh size of a=38–100 mm in the middle part of the Kyiv Reservoir (July–October 2023–2024 and March, July 2025). In total, 1573 net-day catches of gill nets were studied and 30188 fish specimens were subjected to incomplete biological analysis. Catches were divided by mesh size groups (a=38–40 mm, a=50 mm, a=72–100 mm) with the calculation of the number and biomass by species per 100 net-days of a standard net. The collection and analysis of materials was carried out according to generally accepted methods. The volumes of commercial catches were determined according to official commercial statistics. Findings. The catches of fine-mesh nets (a = 38–40 mm) at the Kyiv Reservoir were dominated by roach and silver bream, forming the bulk of the catch both in number and weight. It was found that the share of fine-mesh nets accounted for (in terms of number) 50.4–52.3% of the total bream catch and 65.1–87.2% of the pikeperch catch in the analyzed order of nets, i.e. these nets can cause significant bycatch of their juvenile age groups, which in some years reached 40%. High shares of Prussian carp and pikeperch were recorded in nets with a mesh size of 50 mm, but they also caught significant amounts of juvenile bream, which exceeded the permissible bycatch norms, i.e. specialized fishing with these nets requires strict bycatch control. In large-mesh nets (72–100 mm), the basis of the catches was bream and pikeperch. Bream remained the main target of the fishery, providing more than half of the total catch quantity and biomass. In terms of catch per effort of the main commercial species during 2023‒2025, a significant (3.3 times) decrease was noted for roach and silver bream, while pikeperch was characterized by high stability of catches. The relationship between catch per effort and annual catch (r ≈ 0.53; RІ ≈ 0.31) varied significantly across species and was not strong enough to explain the full extent of variability in annual catch. Originality. New data were obtained and analyzed, which characterize the interannual dynamics of the distribution of catches by the mesh size of commercial gill nets within the framework of scientific support for the protection and use of aquatic biological resources of the Kyiv Reservoir. The theoretical possibility of limited use of catch-per-effort for characterizing commercial fish biomass is shown. Practical Value. The results obtained were used to develop norms regulating fishing in the Kyiv Reservoir, in particular, commercial fishery regimes for 2025–2026 and scientific rationales for the feasibility of specialized fishing of aquatic bioresources. Keywords: reservoir, commercial fishery, catch structure, catch per effort.