Characteristics of the ecological danger of illegal poaching fish catches in the lower reaches of the Irtysh river

Tobolsk Complex Scientific Station of the Ural Branch of Russian Academy of Sciences, Tobolsk, Russian Federation

^* Corresponding author: g-volosnikov@mail.ru

Abstract

Poaching of aquatic biological resources is one of the most common environmental crimes, causing direct and indirect harm to the entire amount of fish stocks. It is necessary to have a clear understanding of the composition and quality of poacher’s catches in order to properly manage fish stocks. This paper examines the poaching catches of the lower reaches of the Irtysh River, based on the data of forensic ichthyologic examinations over the past 9 years. The study showed that the basis of poaching catches is Siberian sturgeon, sterlet, ide, carpbream, nelma, burbot, less in demand, gibel carp, crucian carp, common roach, zander, perch, pike. Poachers harvest Siberian sturgeon, burbot, sterlet, gibel carp, nelma and pike of all sizes, not giving preference only to large or small ones. From 2013 to 2019, sturgeons dominated the catches, but since 2020, the share of cyprinids has increased significantly. An analysis of the fatness of fish in poacher catches shows that poachers try to seize healthy and well-fed representatives of all fish species, except for the Siberian sturgeon, which is harvested regardless of condition.