FISH REPRODUCTION AS A REFLECTION OF FISH FAUNA REFORMING IN THE NOVOSIBIRSK WATER BASIN

Abstract

The article shows the data on the species structure and density of young fish in the Novosibirsk water basin. The data reflect changes in the species structure of the basin and show the role of some species in the fish community. The authors speak about correlation and the number of commercial fish species on the fish breeding ground, relation between the number of young fish and mature fish and their biological parameters. The research finds out that young fish of 6 species (bream, nerfling, roach, perch, pike-perch and burbot) was observed in 1990-s. More than 80 % of all the larvae belonged to the pike-perch and bream that is explained by their big number, big size and high productivity. In 2000-s the researchers found out the replacement of large-scaled fish for indigenous species and invasive species (bleak and Leucaspius). There is a vast community of perch that substitutes the pike-perch on the inshore biotops. For the first time, the researchers observe the larvae of dace that is not typical for the water basin. The article shows increasing number of indigenous species resulted from loss of the pike-perch significance as a biological meliorator in the basin. The paper highlights worsening of biological parameters of the spawning pike-perch; the community of the spawning pike-perch consisted of 71 % of the first spawners aged 3-4 y. Taking into account the minimum size and weight parameters of fish-females (44 sm and 1313 g) and the mass of germ gland about 100 g in 2014, the authors observed the running tiny fish-females with body length 26 sm and mass of 218 g. These tiny species with low fertility prevailed in the second part of the spawning period.