This article analyzes the rate of linear growth of river perch from different ples of the Kuibyshev reservoir, and considers the possibility of identifying ecological forms of this species based on data on the growth rate. The dependence between the growth rate of fish and the hydrological characteristics of the studied areas of the reservoir is revealed. The linear growth rate of male and female river perch was compared, and sexual differences in growth were found. The rate of linear growth of perch in modern conditions of the Kuibyshev reservoir is compared with the results of other researchers.

The article gives general description of perch population of the Kuybyshev reservoir according to the net fishing in 2014-2017, as well as comparison of the results with literature data. The maximum perch specimen caught during the years of research had a body length 40 cm, weight over 1.5 kg and age of 13 years. Maximum life span of perch in the Kuibyshev reservoir has been calculated, which is 17 years. The prevalence of females over males in the populations of perches with the ratio 2:1, the average age of sexual maturity of females and males coincides and makes 3 years. The decay of the reproductive function of the perch occurs after 5 years. Massive spawning of perch in 2016 was observed in the water with temperature 10°C. The maximum value of individual absolute fertility in perch was 370.3 thousand eggs. Differences in the rate of perch growth in various parts of the Kuibyshev reservoir were revealed. A total fish mortality rate made 0.6. The calculation of the catch of perch by the amateur fishermen was made within the Republic of Tatarstan, which amounted to 1.6 tons in 2016. The data of the Tatar department of the State research institute of fisheries "GosNIORH" on the commercial catches of perch in the Kuibyshev reservoir have been presented.

The regulation of the flow of the Volga River by the Zhigulevskaya HPS has changed the living conditions for many fish species. At the same time, the pelagial was a completely new type of biotope for the fish population. The fish population of the Kuibyshev reservoir, newly formed in the pelagial, began to have certain features inherent in this biotope. Currently, according to the results of four years of research, 18 species of fish have been noted here, belonging to 5 families, the basis of which are five species - kilka, sabrefish, bleak, pike perch and bream. It was revealed that the Volga part of the reservoir is more productive than the Kama part, and pelagic fish communities have a certain vertical distribution and migration through the water column, mainly occupying the biomass accumulation zone. The absence of a fishing fleet and the trend in the development of fishing on the reservoir casts doubt on the further rational use of aquatic biological resources in this ecological zone of the Kuibyshev reservoir.