Going from Species Selective to Size Selective in Trawls

There has been much research focus on gear modifications to reduce unwanted catches in trawl fisheries for Norway lobster (Nephrops norvegicus) during the last decade. The Swedish grid, a grid with 35 mm bar spacing and mounted above a 70 mm square mesh cod-end, was introduced in order to minimize impact on local populations of cod, haddock and Pollack from Nephrops fisheries . The Swedish grid is currently the only gear considered selective enough that to be exempted from the effort limits in the North sea management plan due to documented low catches of cod .However, since the introduction, a number of Fishermen have pointed out that the proportion of undersized Nephrops and small flatfish  still remains high. The landing obligation in 2016 in (discard ban) has also increased the urge to improve the size selectiveness of the already species selective gear. By using a stepwise approach were the grid section was modified as well as the codend using different mesh types. The catches of undersized Nephrops decreased with 50 % and small flatfish with 70 % compared with the standard grid. This study shows how strong incitement can improve the selectivity of a gear to a higher  level