Out with the old and in with the new: T90 codends improve size selectivity in the Canadian redfish (Sebastes mentella) trawl fishery

The size selectivity of four codends were compared in the Gulf of St. Lawrence, Canada, redfish fishery (Sebastes mentella), including the regulated diamond mesh codend with a mesh opening of 90mm(T0) and three experimental codends of different mesh openings (90, 100, 110 mm) in which the netting is turned 90 degrees to the direction of tow (T90). Results for the regulated codend showed that there was little size selection, catching greater than 97% of redfish over all of the length classes observed. Considering the fished population, the smallest T90 codend would catch 30% fewer redfish under the minimum landing size (MLS) of 22 cm compared with the T0 codend, but would also lose 16% of catch above 22 cm. The T90 codend with 100 mm mesh opening had the same size selectivity as the smallest T90 codend. The 110 mm T90 codend would catch 50% less redfish below MLS but lose 40% of redfish above MLS. Overall, results show that T90 codends improve size selectivity in which large proportions of undersized fish are successfully released.