Citation
Summary
Seabirds of conservation concern, including black petrel (Procellaria parkinsoni), are incidentally captured on bottom-longline fishing gear deployed in inshore commercial fisheries in northern New Zealand. These fisheries target a variety of fish species, including snapper (Pagrus auratus), bluenose (Hyperoglyphe antarctica), hapuku and bass (Polyprion oxygeneios, P. americanus), and ling (Genypterus blacodes). Using government fisheries observer placements conducted over 76 fishing days between December 2012 and May 2013, we investigated the efficacy of operational practices in use in these fisheries for reducing seabird bycatch risk. In addition, we explored potential new measures for reducing seabird captures. Four main components of operational practices are expected to influence seabird bycatch risk in northern bottom-longline fisheries: the time of day at which longlines are set, the sink rates of hooks, the deployment of streamer lines, and the retention of fish waste during setting and hauling. To reduce the risk of seabird captures in inshore bottom-longline fisheries in northern New Zealand, we recommend that the efficacy of line-weighting strategies in use is increased. This recommendation may involve adding more weight to lines and sinking hooks closer to the boat (e.g., using closer weight spacing, more even-sized weights, longer float-ropes, denser weights and slower setting speeds). In addition, we recommend that longlines are set prior to nautical dawn, fish waste is held on-board during hauling, the design and construction of streamer lines is improved, the improved streamer lines are deployed on all sets, and sinking longlines to 10 m depth at the end of streamer lines is considered as a minimum performance standard. In combination, these measures are expected to significantly reduce the risk of seabird captures in inshore bottom-longline fisheries.