Ichthyocene of the Western Chukchi Sea – interpretation of the results of bottom trawl surveys obtained by different methods

The purpose of the work: interpretation of the results of bottom trawl surveys in the 2010 s , obtained using different methods during the study of the fish community of the western Chukchi Sea. Methods used: ichthyocene clustering was performed using the SSA method based on limited correspondence analysis or canonical analysis with constraints (depth, latitude). Survey results were normalized to the area of a common polygon, which was defi ned as the 2020 survey area. Biomass dynamics of common species and their spatial properties were assessed using the VAST package. Biomass and abundance of all fish species were calculated using the Voronoi-Dirclet cell area method. Novelty: the spatial distribution of the ichthyocene in the Western Chukchi Sea is characterized by division into two clusters along the 100 m isobath. The quantitative and qualitative composition of fish on the Chukchi shelf was more similar to those in the northern Bering Sea than to the adjacent Arctic Ocean. The depletion of the species composition and abundance of the sea’s ichthyofauna was noted in a northerly direction and with increasing depth. The standard polygon was identifi ed within which, using three methods accounting for different trawl openings, fish biomass was calculated, dominant species (Arctic cod in 2010-2014, walleye pollock in 2018-2020), as well as secondary species that determine the appearance of the fish community, were identified. In total, the presence of 14 common and 17 abundant fish was detected, the regular census of which will allow tracking possible changes in the ichthyocene under the influence of various environmental factors. Practical significance: the obtained results will contribute to a better understanding of the functioning processes and interannual variability of the fish community of the Chukchi shelf and should be taken into account in subsequent research in the waters of the eastern Arctic.