Ecological and biological aspects of zander and Volga zander reproduction under conditions of the Zaporizhzhia reservoir (Ukraine)

Through the example of zander and Volga zander it was researched the current state of the populations of predatory species of fish, and their biological and ecological characteristics of reproduction under conditions of the Zaporizhzhia reservoir. It is determined that populations of experimental species of fish are in a depressed state. In zander, the index of individual absolute fertility is twice higher than such of Volga zander. The zander and Volga zander belong to a group of fish with synchronous growth of oocytes, a one-time and short-term type of spawning. By the features of oogenesis, females of these species of fish belong to a group of fish that hibernate with ovaries at IV stage of maturity. The artificial spawning nests were designed and complex of ecological measures for their installation and maintenance with the purpose of restoration of natural spawning grounds of experimental species of fish were developed. The results of research can be applied at realization of a number of measures on rational use and restoration of natural populations of zander and Volga zander in regulated and anthropogenically transformed reservoirs.