Development of approaches to regulation of flatfish fishery in the West Bering Sea zone

Abstract

It is demonstrated based on results of bottom trawl surveys, that basis of flatfish resource in the West Bering Sea zone is formed by flathead sole, Alaska plaice and northern rock sole, respectively 40.3, 35.1 and 19.6% in the total flatfish biomass averaged for the period 2000–2021. Almost three quarters of the estimated flatfish stock of the zone are within the Anadyr Gulf. In 2001–2021 the stock was relatively stable and demonstrated a slight trend to growth. Estimates of the total biomass increased from 153 thous. t in 2001 to 230–305 thous. t in 2020–2021. The analysis of the current flatfish fishery showed that the major contribution to annual catches is made by the specialized fishery by bottom trawls – 39.4% and by Danish seines – 25.4%, and about 12.8% is taken as by-catch in the walleye pollock fishery by pelagic trawls. About 77.1% of the annual catches of flatfish reported in the West Bering Sea zone are taken from 169°E in Olutor Based on the analysis of the annual flatfish catch by different types of fishery, species composition of the catches and seasonal catch dynamics, the average proportion of northern rock sole in the total annual catches was about 53.1%. It is shown, that stocks of northern rock sole in this area bear the main fishing load, and Alaska plaice and flathead sole are not developed in full. Optimal scheme of the flatfish TAC assessment for the West Bering Sea zone is developed. It includes calculation of commercial biomass of northern rock sole by cohort methods, development of its fishery regulation rule, the TAC assessment based on this rule and assessment of possible by-catch of “minor” flatfish species based on their long-term proportional contribution into the catches.