Evaluation of the Number of Early Young Fish on Coastal Spawning Grounds of the Meshinsky Gulf of the Kuybyshevsky Water Reservoir

Abstract

The results of six-year observations (2012-2017) in the Meshinsky Gulf of the Kuibyshev reservoir concerning the evaluation of the reproduction efficiency of the main commercial fish of this section of the reservoir have been reviewed and analyzed. Data are given on the species composition of prolarvae and larvae of fish in the coastal part of the reservoir. It has been established that the most abundant in the studied years was the fry of roach, bream and silver bream; the larvae of carp and ruff were least common in catches. A method for estimating yields by catches of fish larvae based on deviations in the mean value of the catch has been proposed. According to these data, in 2012-2017 there was one high-yielding generation, in the remaining years - medium-yielding. It is shown that the dynamics of the number of fish larvae in the coastal region depends on the course of spawning and obeys the normal distribution in time. Analysis of the relative indices of the quantity of larvae - pieces/catches and pieces/1m of the coastal area in the studied years has been given. A method is described for calculating the absolute abundance of fish larvae in the littoral by the example of the Meshinsky Gulf. According to calculated data, the average number of early juveniles in the littoral of the Meshinsky Gulf in 2012-2017 was about 4 billion specimens, which corresponds to the figures obtained in previous years in the Sviyazhsky Gulf of the Kuibyshev Reservoir. The study results have great practical importance and can serve as data for prediction of catches and determining the state of ecological system of the reservoir.