Rare and endangered populations of Fringebarbel sturgeon, Acipenser nudiventris Lovetsky, 1828, in Kapshagai Reservoir and Ili River on the territory of the Republic of Kazakhstan

This article presents the analysis of literature data published from 1970 to 2020, data obtained in 2021-2023 as a result of research work, as well as data during conversations with fishermen and fishery inspectors on the current state of Fringebarbel sturgeon, Acipenser nudiventris Lovetsky, 1828. Fringebarbel sturgeon belongs to the sturgeon family, a rare and valuable fish species. Its natural habitat is the rivers of the Black, Azov, Caspian, and Aral Sea basins and their tributaries. Fringebarbel sturgeon is one of the most vulnerable and few sturgeons in the world, and its isolated specimens are still found in the Balkhash-Ili basin (Kazakhstan - China) due to its migration in 1933-1934. Notably, this is the only example of successful sturgeon acclimatization. In 2021-2023, research work in the Kapshagai reservoir and the Ili River was performed in May-August at 10 stations. Results of the research revealed that the Fringebarbel sturgeon population is extremely low, and only juvenile Fringebarbel sturgeon are occasionally caught in catches.