Features of changes in water bioresources of the kuibyshev reservoir under modern climatic and hydrological conditions.
Authors: Kalaida M. L. , Sharafutdinov R. G. 
Published: September 2023

The RELEVANCE is determined by the need to solve environmental problems in the operation of reservoirs. The Kuibyshev Reservoir has been functioning since 1957 and in the recent period there have been significant changes in the temperature and hydrological regime, which is reflected in the qualitative and quantitative composition of the ichthyofauna. Management of aquatic bioresources is necessary to improve the ecological situation and food security of the region.

THE PURPOSE. Consider the species composition of catches, the quantitative representation of fish in the actual catch under the conditions of the current level and temperature regimes in the areas of the Kuibyshev reservoir within the Republic of Tatarstan; identify the main trends in changes in the qualitative and quantitative composition of the ichthyofauna to determine ways to preserve and improve the quality of aquatic biological resources. METHODS. A comparative analysis of our own research and literature data on the fishery characteristics of the Kuibyshev reservoir, fish productivity and the state of the ichthyofauna was carried out. In this work, to analyze the current state of the species composition of catches and the representation of fish in the actual catch, we used data provided by the State Committee of the Republic of Tatarstan on Biological Resources. RESULTS. The qualitative and quantitative composition of aquatic bioresources of the Kuibyshev reservoir under modern conditions of changing climatic characteristics and hydrological regime are considered. Particular attention is paid to the state of ichthyocenoses of the Kuibyshev reservoir within the Republic of Tatarstan. An analysis of the dynamics of changes in fish catches in the Volga River and the Kuibyshev reservoir was carried out. It is shown that the basis of the fishery is formed by bream, silver bream, blue bream, roach and pike perch. Blue bream, silver bream and bream together practically determine about 65% of the catch. Under these conditions, from the standpoint of improving the composition of the ichthyofauna and its directed formation, the role of such active predators as zander and bersh increases significantly. The features of the dynamics of catches of zander and bersh are considered. It is shown that the increase in the share of zander and bersh in catches is associated with an improvement in their food supply - with an increase in the number of weedy fish, among which sprat is important as a food component. It is concluded that the absence of a significant catch of sprat contributes to the growth in the number and, accordingly, the catches of bersh and pike perch. It is noted that water discharges from the reservoir do not significantly affect the stocks of pike perch. CONCLUSION. The assessment of the fish productivity of the Kuibyshev Reservoir within the Republic of Tatarstan in the temporal aspect and for fishing areas showed that in all fishing areas of the Kuibyshev Reservoir, fish productivity has been increasing in recent years. The highest fish productivity according to the results of the actual fish catch is noted in the Tetyushsky and Spassky areas. The average fish productivity in recent years was 31.53 kg/ha in Tetyushsky and Spassky plots, 11.89 kg/ha in Kamsko-Ustyinsky, 8.11 kg/ha in Laishevsky and Alekseevsky, 7.19 kg in Rybno-Slobodsky, ha, Mamadyshsky and Yelabuga plots - 18.15 kg / ha. It is concluded that the observed process of accelerating the eutrophication of the Kuibyshev reservoir under conditions of changing external climatic conditions and the current hydrological regime leads not only to the “blooming” of water, but also to an increase in the degree of trophy (within the mesotrophic class of water quality).