RESEARCH OF NATURAL FISH REPRODUCTION IN THE URAL RIVER IN THE WEST KAZAKHSTAN REGION OF THE REPUBLIC OF KAZAKHSTAN
The article highlights the conditions for natural reproduction of fish in the Ural river in the West Kazakhstan region. Spawning of semi-anadromous and migratory fish in the lower and middle Ural on the territory of Kazakhstan has great importance for growing qualitative composition of fish populations due to the vigorous recruit-stocks. There are given the data obtained in the course of research in 2007-2018 by the researchers of a regional affiliate of Kazakh Research Institute of Fisheries. Concentration of fish juveniles in the river, dynamics of numbers, size and weight data have been brought, as well as new fishing gear for juveniles developed and tested in 2012-2018. The data on the hydrological regime of the reservoir and its influence on the efficiency of fish spawning are highlighted. It has been stated that in arid years insufficient water content and short flood period create unfavorable conditions for spawning phytophilous specious, especially, for late spawning of sazan. There has been shown the yearly interrelation between hydrological parameters and juvenile productivity. The flood land spawning grounds of abundant phytophilous specious in the Ural are found to require a regular technical melioration because of fast weediness in summer and girts clogged with snags during the flood. Absence of sturgeon species in samples signals for the lack of their natural productivity and the need of stocking the middle part of the Ural with beluga, ship, sturgeon juveniles. Recommendations for improving the conditions of natural reproduction of fish in the reservoir have been presented.