REPRODUCTION CONDITIONS AND SPAWNING EFFICIENCY OF FISH IN THE DNIEPER-BUG ESTUARY

There has been studied current dynamics of basic abiotic factors of fish habitats, which deter mine reproduction efficiency of fish fauna of the Dnieper-Bug estuary system. There have been analyzed qualitative and quantitative changes of the composition of juveniles of major commercial and mass fishes of this water body. It was determined that the main factor, which determines fish juvenile yield indices is the Dnieper river flow, which currently depends in a full degree on water discharges in lower race of the Kakhovka HEP. In little water years, there has been observed penetration of salt seawaters into estuary parts of the Dnieper River that results in decrease of fish juvenile number and as a result in formation of scanty generations. It is recommended that the water discharge into lower race of the Kakhovka HEP during summer period stabilized at the level of not lower than 1000 m3/s.