Seal exclusion devices in cod pots prevent seal bycatch and affect their catchability of cod

Abstract

In order to maintain a viable inshore fishing industry, it is important to limit the incidence of seal-inflicted damage to static fishing gear and additional catch losses. Studies in the Baltic Sea have shown that this could be achieved by implementing alternative fishing methods, e.g. by using fish pots instead of lines or gillnets. However, as in net and line fisheries, a pot fishery could also result in bycatch of seals. In order to prevent these bycatches, pot entrances were equipped with seal exclusion devices (SEDs) of various sizes and shapes. A field study was conducted to investigate what effect different types of SEDs had on the bycatch of seals as well as on the pot's catchability. When pots where equipped with SEDs the bycatch of seals was reduced to zero without negatively affecting the pot's catchability. The shape and size of the entrance did have a significant effect on the pot's catchability and the size of the fish. Using symmetrical oval shaped entrances along with larger rectangular entrances divided into two smaller openings increased the pot's catchability.