Make fisheries better by reducing size selectivity in the North-east Arctic bottom trawl fishery

In the Barents Sea demersal trawl fishery targeting gadoids it is mandatory to use a fish sorting grid with a minimum bar spacing of 55 mm. However, earlier studies have reported low catch efficiency for this gear, resulting in increased fishing effort, higher fuel use and greenhouse gas emissions, and seabed disturbance to catch available quotas. The present study investigated the effect of reduced grid bar spacing on capture patterns and efficiency. The results demonstrated that reducing grid bar spacing by 10 mm improved catch efficiency for cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and saithe (Pollachius virens) by 51 %, ' 100 %, and ' 300 %, respectively, measured in numbers of fish. Despite the reduction in bar spacing, the fraction of undersized fish captured remained low and did not exceed 2 % for any of the species investigated. Quantified by weight, a 10 mm reduction in grid bar spacing resulted in 26 %, 82 %, and ' 200 % increase in catch for commercially sized cod, haddock and saithe, respectively, with the fraction of undersized fish not exceeding 1 %. Since the fraction of undersized fish was low for all species, the use of non-selective codends that promote catch quality may be a future viable option. Our results indicate that environmental impacts could be reduced and profitability increased by allowing fishers to use sorting grids with smaller bar spacings. However, additional studies are needed to confirm our results can be extrapolated beyond our case study, as they depend on the size structure of the fish populations encountered during the trials.