Unanswered Forum Topics

Cory's shearwater, Calonectris diomedea, is the main seabird species incidentally caught by the Spanish longline fleet in the western Mediterranean Sea. The authors used onboard observer data to model the longline bycatch of Cory's shearwaters as a function of time of the year, technical characteristics of the fishing operation, and geographical location. The most explanatory factor for bycatch was the geographical location and then the technical characteristics (number of hooks and fishing during non-working days).

This study examined the spatial and temporal variations in bycatch rates of four species of great albatrosses. Observer data was obtained from the Uruguayan pelagic longline fleet and Japanese vessles operating in Uruguay. Vessel operational practices and habitat variables affected bycatch rates, including: setting time, moon phase, and area and season. 

Potential risk of fisheries to cetaceans was assessed using a screening procedure based on a Productivity Susceptibility Analysis (PSA) using gears found in Ireland. Gillnets targeting demersal species was assessed as the fishery posing the greatest risk to cetaceans. Pelagic trawls targeting small pelagic species was found to pose a moderate risk to cetaceans. Specific gear-species interactions were also identified, such as humpback whales and pots/traps.  

The long-term effectiveness of acoustic pingers in reducing marine mammal bycatch was assessed in the California swordfish and thresher shark drift gillnet fishery. Bycatch was observed at sea between 1990 and 2009, with acoustic pingers being present from 1996 to 2009. Bycatch rates of cetaceans decreased by around 50% when pingers were present; the decrease was mostly driven by common dolphins. Beaked whales have not been incidentally caught since 1995. Pinger failure occurred in less than 4% of observed sets.