Biological fundamentals of stocking the Zaporizhzhia (Dnipro) reservoir with fish

Purpose. The main purpose is developing effective measures for stocking the Zaporizhzhia (Dnipro) reservoir with valuable fish species by studying the biological and fishery aspects of the formation and exploitation of their commercial stocks. Methods. During the work, we used the generalized results of integrated hydrobiological studies performed in 2015-2017. Materials were collected in the Zaporizhzhia (Dnipro) reservoir using standard fishing gears for fish sampling. Collection and processing of phyto-, zooplankton and zoobenthos samples were carried out using conventional hydrobiological methods. Calculation of fish seed amounts was carried out using classical fishery and ichthyological methods. Findings. The status of fish feed supply of the Zaporizhzhia (Dnipro) reservoir and its production potential was determined. Based on the obtained data, we calculated the potential productivity of the reservoir. It was found that the reservoir had certain feed supply reserves allowing large scale stocking with the juveniles of commercial fish species. The recommended amounts of reservoir stocking in 2017 were calculated as follows: 570 thousand 1+ carp (weight 100-130 g); 1560 thousand 1+ silver carp (weight of 100-130 g); 400 thousand 1+ bighead carp (weight of 100-130 g); 220 thousand 1+ grass carp (weight of 100-130 g); 135 thousand 0+ tench (weight of 10-20 g); 83 thousand 0+ pike (weight of 100 g); 83 thousand 1+ pikeperch (weight 100 g). Scientific novelty. The presented results of the study of the state of fish feed supply in the reservoir allow stocking with the calculated amounts creating the bases of the rational use of aquatic bioresources with the preservation of the productive potential of commercial fish species exploited by commercial fishery in the Zaporizhzhia (Dnipro) reservoir. Practical value. Stocking the reservoir with fish allows improving the overall ecological status of the reservoir and increasing fish productivity under the conditions of commercial fishery exploitation.