Current status of native crayfish populations in Russia: A brief review of their biology and fisheries

Historically, Russia has been a leader in the production of freshwater crayfish, with annual exports reaching 2000 t. However, the spread of crayfish plague led to a sharp decline in population densities in the 1970s. In this review, we provide an update on the current status of native crayfish populations in Russia, focusing on their biology and fisheries. The noble crayfish Astacus astacus primarily occur in the northwestern and central regions of Russia, whereas the narrow-clawed crayfish Pontastacus spp. are predominant in the Volga River basin and southern regions. The thick-clawed crayfish inhabits lagoons and estuaries in the Caspian Sea, Sea of Azov, and Black Sea. Between 2012 and 2015, annual catches fluctuated significantly. However, in the following four years, these figures stabilized, with a noticeable upward trend from 2020 onwards. A significant proportion of the total crayfish supply came from reservoirs, with an average contribution of 46 %. In addition, lakes, rivers, and other water bodies collectively contributed average share of 54 %. The Volgograd Reservoir, the Saratov Reservoir, water bodies along the left bank of the Volga River, and the Kuibyshev Reservoir are particularly important in terms of crayfish abundance and production accounting for 79 % of the total crayfish stock. The observed fluctuations in crayfish abundance are mainly due to environmental factors. The fisheries sector faces major challenges, including illegal fishing and habitat degradation.