Prospects of commercial exploitation of Prussian carp in the Kyiv reservoir

Purpose. Establishing modern parameters of Prussian carp population as a promising object for increasing commercial fish productivity of the Kyiv Reservoir. Methodology. The work is based on field materials obtained during the period 2019-2021 on the Kyiv Reservoir. Data collection and processing was carried out in accordance with generally accepted methods. Ichthyological material was collected from catches of the survey gill nets with mesh sizes of 30-120 mm and commercial gill nets with mesh sizes of 38-50 and 75-100 mm. A total of 1215 net-days of surevy and commercial nets were analyzed during the study period, of which 2372 specimens of Prussian carp were analyzed. Statistical data processing was carried out using MS Excel. Findings. The main parameters that characterize the commercial stock of Prussian carp of the Kyiv Reservoir in the context of optimizing the commercial fishing pressure on this species have been determined. It was found that the state of recruitment of the commercial stock of this species was satisfactory and the dynamics of its size-age structure indicated a low commercial fishing pressure, especially on the right wing of the variation series — the average annual fishing mortality in 2019-21 was φM=0.13. The majority of the commercial stock is steadily composed of age-6 to age-10 fish, the share of older age groups was consistently high, which led to fluctuations in the weighted average age in catches within 6.7...8.5 years. It was shown that the intensification of Prussian carp harvest (due to specialized fishing with nets with mesh size of 50 mm) would allow increasing catches in the Kyiv Reservoir by 52...65%. Originality. For the first time, a detailed description of Prussian carp of the Kyiv Reservoir is presented as an adventive species that quickly assimilates free econiches and requires scientifically based measures to localize its abundance. Practical value. Based on the processing of information on the state of stocks of Prussian carp as part of the source of commercial fishery of the Kyiv Reservoir, the procedure of intensification of its commercial exploitation was determined, taking into account both fishery and environmental aspects. Proposals regarding the quantitative characteristics of specialized fishery with nets with mesh sizes of 50-60 mm are included in the new edition of the Rules for commercial fishery in inland fisheries water bodies (parts thereof).