Biological Parameters of Sturgeons from the Ural (Zhaiyk) River in the Republic Kazakhstan According to Data on Illegal, Unreported, and Unregulated Catches

This paper analyzes the dynamics of occurrence of four sturgeon species from the family Acipenseridae (Russian sturgeon Acipenser gueldenstaedtii, sterlet A. ruthenus, stellate sturgeon A. stellatus, and beluga Acipenser (Huso huso) in IUU catches from the Ural (Zhaiyk in Kazakh) River in the Republic of Kazakhstan. Data on the arrested IUU catches of the annual quantity of sturgeons from 2012 to 2018 are given that demonstrate fluctuations in the amount of Ural River sturgeons from this river, as well as the male dominance in their populations. Biological parameters of Ural sturgeons (sex ratio, age, weight, length, and length–weight ratio) during the period of maximum catches in 2018 are given.