Investigating the potential of escape openings and reduced mesh size to optimize snow crab (Chionoecetes opilio) pot catches in the Barents Sea

In the Barents Sea Norwegian pot fishery for snow crab (Chionoecetes opilio), fishing effort regulations and bait expenses create incentives to improve the catch rates. The fishery also currently captures a large proportion of sub-legal sized crab which must be sorted out and released. In this study, we used comparative fishing trials to determine the size dependent capture efficiency of three modified pot types designed to address these issues. A pot constructed with 40 mm mesh caught ∼35% more (CPUE, number of individuals per soak time) large crab (≥ 100 mm carapace width [CW]) than the pot typically used in the commercial fishery (140 mm mesh). However, it also retained massive amounts of small individuals (< 100 mm CW). The addition of four stadium shaped escape openings into the 40 mm and 140 mm mesh designs resulted in large reductions in catches of small crab, but also a ∼30% reduction in large crab. Analysis of size dependent catch comparison rates and selectivity parameters supported the CPUE findings. Of the tested designs, catches were best optimized by the currently used commercial pot. However, we conclude that a small mesh pot with escape openings has the potential to increase catches of large crab and reduce catches of non-commercial small crab. Further development of this design, particularly in terms of the dimensions of the escape openings, is therefore required. •Capture efficiency of four snow crab pot designs were compared.•Pots had either 40 mm or 140 mm mesh, and either escape openings or not.•The 40 mm mesh increased catches of all sizes of crab compared to 140 mm.•Escape openings reduced catches of small sized crab but also large crab too.•Catches were optimized best by the 140 mm mesh pot with no escape opening.