Effect of the lifting panel on selectivity of a compulsory grid section (Sort-V) used by the demersal trawler fleet in the Barents Sea cod fishery

Abstract

In this study we investigated the effect of the lifting panel on the selectivity of a compulsory grid section (Sort-V) used by the demersal trawler fleet in the Barents Sea cod fishery. Ideally, every fish passing through the grid section of the gear would make contact with the grid and be retained or released depending on size. However, in reality some fish may not be able to make contact with the grid or may actively avoid making contact with it. The purpose of the lifting panel is to make the grid contact probability, Cgrid (the proportion of fish that contact the grid), as high as possible. We found that the presence of the lifting panel has a significant effect on Cgrid, as the proportion of fish that came in contact with the grid was reduced from 82% when the lifting panel was present to 67% when the lifting panel was removed. For cod that were making contact with the grid, the mean selectivity parameters, L50grid and SRgrid, were 51.06cm (50.26–51.87cm) and 7.91cm (7.33–8.48cm), respectively, which is in agreement with values estimated for similar grid sections in previous studies. This study highlights the importance of the lifting panel for increasing the effectiveness of the grid section tested.