Long-Term Dynamics of Sturgeon Distribution in the Northern Part of the Caspian Sea (Review)

Abstract In the past 50 years, habitat conditions and distribution of sturgeons in the Caspian Sea have significantly changed. The longest term records of sturgeon distribution are obtained for the northern part of the sea, which is extremely important for the feeding of these species. In the present review, we summarize and analyze changes in the distribution of the beluga Huso huso L., 1758; Russian sturgeon Acipenser gueldenstaedtii Brandt, 1833; and stellate sturgeon Acipenser stellatus Pallas, 1771 in the northern part of the sea from 1970 until 2014 and the biotic and abiotic factors of these changes. The effect of the sea-level fluctuations, the biomass of food organisms, and the total abundance of the studied fish species on their distribution is demonstrated.