Evaluation of the efficiency of natural reproduction of fish in the conditions of the Volgograd reservoir

Abstract

The main factor influencing the success of the reproduction of limnophilous fish is the height of the level and the duration of the spring flood with uniform water heating. Given the impossibility of regulating the operation of HPSs in accordance with fishery recommendations, due to the isadvantage of these rhythms for the shareholders of the energy sector, the search for environmental factors that can be influenced by the forces of the agricultural sector seems to be extremely relevant. The reproduction of fish was studied in the area of the middle zone of the Volgograd reservoir near the villages Akhmat and Zolotoye, Krasnoarmeysk district, Saratov region, from 2017 to 2021. In total, reproduction of 19 fish species was recorded in the studied water areas. In 2017, a high yield of juvenile fish was noted in the considered section of the reservoir, in 2018 there was an average yield, in subsequent years yield was very low. The production characteristics of spawning and feeding grounds of the corresponding area were studied. The dependence of the efficiency of fish reproduction on the productivity of shallow waters is shown. The relationship between the deficit of net primary production, the level and temperature regimes of the Volgograd reservoir and the damage caused to fish reproduction by the deficit of net primary production is mathematically described for the study area of the reservoir over a five-year period. One of the reasons for the deficit of net primary production is considered (expressed in mg O2/l): outbreaks of blue-green algae blooms in July-August, which also leads to death phenomena.