MODERN COMMERCIAL AND BIOLOGICAL CHARACTERISTICS OF ZANDER SANDER LUCIOPERCA OF THE KYIBYSHEV RESERVOIR
The article presents the research materials of pike perch r. Volga and the Kuibyshev reservoir and noted the changes that have occurred in its population. Prior to the creation of the reservoir in the conditions of the Middle Volga, male zander matured at the age of 5-6 years, females at 6-7 years. In the Kuibyshev reservoir, pike perch becomes sexually mature at the age of 4-5 years, and a small part of it matures at the age of three. In the reservoir, due to ecological plasticity and the ability to lay eggs in a wide temperature range, regardless of the level regime of the reservoir and the spawning substrate, a gradual increase in its biological indicators, abundance and reserves began to be noted. Improving the feeding conditions of zander in the reservoir contributed to earlier puberty, an increase in the absolute fecundity of fish and its abundance in the reservoir. This contributed to an increase in zander catches since 1974, which in 1985 reached a maximum of 517 tons (9,2% of the total fish catch in the reservoir). Sufficiently high catches of zander over the past 10-15 years indicate the stability of its stocks in the Kuibyshev reservoir, which currently tend to increase. The multi-age sizeweight composition of zander in the Kuibyshev reservoir is represented by both young and older individuals, and confirms that the population is in good condition.