Some data on the selectivity of the fishery walleye Pollock in mid-water trawls in the north-eastern part of the Sea of Okhotsk, Pacific waters adjacent to Kamchatka and the Northern Kuril Islands

As a result of the conducted studies, it was found that in 2016–2020, the main contribution to the total catch of pollock in the northern part of the Sea of Okhotsk, in the Pacific waters adjacent to Kamchatka and the northern Kuril Islands, was provided by trawls of the so-called «western» projects. In the first area, the most common among these types of trawl was «Atlantic 1240», and in the second area — «Gloria 928 WB». In the same areas, at the same time, catches per unit effort on BATM and SRTM vessels with «western» projects («Atlantic 1240» and «Gloria» 928 WB») tended to be higher, mean length and weight lower, and relative number of fish below the commercial measure higher than with «far eastern» projects («154/1120 m trawl Pr. 342») and «99/624 m Pr. 280»). As a consequence, in the last 5 years, an increase in juvenile pollock in commercial trawl catches was recorded in the areas under consideration compared to the period 2002–2015, which is not related to the yield of generations. According to the nature of the set of rope elements and taper of the shell, we can conclude that the use of trawls «Gloria» and «Atlantic» allows trawling over thin clusters of pollock at high speeds, which leads to a larger volume of filtered water, and, therefore, to a larger catch per unit effort. The increase in the number in catches of younger fish against the background of a decrease in older fish in 2016–2019 can be associated with the use of trawls «western» projects exclusively in the water column, where the number of small fish is greater. Practical implementation of the research is the introduction of an additional period of selectivity of fishing mortality (2016–2019) in 2019 in stock assessment and justification of TAC of the North Pacific pollock using the «Synthesis» model