The study was carried out on the basis of the analysis of poaching sturgeon species in the lower reaches of the Irtysh River (the Tyumen region and Khanty-Mansi Autonomous Okrug), according to the results of forensic ichthyologic examinations over the period from 2013 to 2020. The size and weight ratio of Siberian sturgeon and sterlet in catches, the average weight of one fish species, the number of examinations performed, as well as the dynamics of these indicators for the considered time period were evaluated. As a result of the analysis performed, there has been seen an upward trend in the number of expert examinations (from 10 in 2013 to 25 in 2020). Among sturgeon species sterlet dominates in size, with the exception the period of 2017-2018. There has been stated the dynamics of increasing mass of Siberian sturgeon and, accordingly, a decrease for sterlet, with the average share of sturgeon to be less 50%. The average mass of a Siberian sturgeon species has increased from 0.8 to 1.2 kg, as well as a positive trend for the above period is noted when analyzing the total mass of sturgeon species during yearly examinations. Body mass of poached sterlet species hasn’t increased over the 8-year period, and its average value made 0.11–0.13 kg. Over the investigated period the number of forensic ichthyologic examinations has increased, the average mass growth dynamics in a Siberian sturgeon species has been stated, with predominating of immature species in both of sterlet and Siberian sturgeon catches.
ichthyologic examination, Siberian sturgeon, sterlet, quantity, mass, the Irtysh River, the Ob-Irtysh basin
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