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.
Seabird Bycatch Mitigation Development
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.
The National Marine Fisheries Service Pacific Islands Fisheries Science Center (NMFS PIFSC) also tested tori lines, blue dyed bait and weighted hooks in 1999, They found that baits dyed blue and baits with additional weight reduced the number of interactions with both black-footed and Laysan albatross. Tori lines reduced contact between baits and albatrosses by 70%
The WPRFMC's plan for implementing seabird mitigation measures was for a Fishery Management Plan (FMP) amendment where fishermen could choose the measures from a selected list of proven mitigation methods. However, this was forestalled by a 2000 US Fish and Wildlife Service Biological Opinion (BiOp) on the endangered Short-tailed albatross in, which prescribed what seabird mitigation measures would be used by the tuna-targeting (deep sets) and by swordfish (shallow sets) as follows:
Summary of seabird deterrent measures by set type
The WPRFMC incorporated these measures into a Pelagics FMP amendment in 2002, requiring that these seabird mitigation measures be used when fishing north of 23 deg N. This measure was further refined in 2006 by an FMP amendment that allowed operators of Hawaii-based longline vessels fishing north of 23 degrees north latitude, as well as those targeting swordfish south of 23 degrees north, to utilize side-setting to reduce seabird interactions in lieu of the seabird mitigation already measures required.
The implementation of the seabird measures caused a massive drop in seabird interactions by more than 90% in the Hawaii longline fishery.
Sea Turtle Bycatch Mitigation Development
Despite low observer coverage, usually 5% or less, it was estimated that prior to 2001, a total of 666 turtles were caught annually in the Hawaii longline fishery: 418 loggerheads, 146 olive ridleys, 112 leatherbacks and 40 green turtles.