Use of selective devices in trawls to support recovery of the Kattegat cod stock: a review of experiments and experience

The spawning-stock biomass of cod (Gadus morhua) in the Kattegat area is at a historically low level. Throughout the past decade considerable efforts have been devoted to research on improving both species and size selectivity of the trawls used in the mixed demersal fishery in the area, because this provides a valuable management tool for reducing the bycatch of cod and reducing mortality, and thus helping to rebuild the depleted stock. Gear research in the area has been focused on devices that allow for continued exploitation of the Norway lobster (Nephrops norvegicus) and flatfish, but minimizing the bycatch. We review the results of previous and continuing experiments with various codend mesh sizes, mesh configurations, escape windows, sorting grids, sorting frames, and separator panels, but also changes in whole-trawl designs. Based on our review, we compare and discuss the gear-related technical measures and their effectiveness in maintaining a commercial fishery on viable stocks, yet protecting cod. We discuss the results in relation to changes in legislation and experience with implementation of new selective devices in recent years. We also discuss ways to create stronger incentives for fishers to participate in gear research and to increase acceptance of more selective gears.