Longline bycatch in Hawaii

The Hawaii longline fishery is managed under Western Pacific Regional Fishery Management Council’s (WPRFMC's)Pelagics Fisheries Ecosystem Plan (formerly Pelagics Fisheries Management Plan). Through this plan, the WPRFMC has introduced logbooks, observers, vessel monitoring systems, fishing gear modifications and spatial management for the Hawaii longline fishery. Until relatively recently, the main driver for management of the Hawaii longline fishery has been bycatch and not fishery resources.

The revival of the Hawaii longline fleet in the late 1980s meant that larger ocean-going longline vessels began operating from Honolulu. The advent of the new fleet was driven primarily by targeting swordfish, which meant using squid bait on hooks deployed in relatively shallow depths (<30 m) and with light sticks attached to the branch lines. Observers began to be employed on vessels in 1994 and it soon became apparent that in the shallow set fishery there were catches of sea turtles and seabirds. The principal seabirds caught were black-footed and Laysan albatross, and for the turtles, loggerheads and leatherbacks. There were turtle and seabird interactions in the deep set fishery also, but these were one to two orders of magnitude lower than in the shallow set fishery.

Prior to 2001, 1380 black footed albatross and 1163 Laysan albatrosses were caught annually by the Hawaii longline fishery. The WPRFMC's response to the volume of seabirds being caught was to mount a project through 1998 and 1999 to test various seabird mitigation methods. It was found that during gear setting operations, blue dyed baits were the most successful mitigation method, followed by strategic offal discards. Tori lines and a towed buoy system also proved to be effective mitigation measures during the set. During hauling operations, blue dyed baited and tori lines were found to be equally effective mitigation strategies, followed by the towed buoy. Retaining offal on the vessel during the haul increased seabird interactions.

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