Hawaii's pelagic fisheries

Marine Fisheries Review, Spring, 1993 by Christofer H. Boggs, Rusell Y. Ito

A special "line thrower" is required to put sag into a monofilament longline as it is deployed (Kawamoto et al.(11); Boggs, 1992) so that it can fish deeply for bigeye tuna. Many new entrants to the fishery in 1989-91 did not invest in line throwers. These vessels fished shallow even when targeting tuna (daytime fishing) and probably contributed to the increase in the relative proportions of yellowfin tuna, blue marlin, and other shallow-swimming species caught by longliners in recent years (Fig. 1A). The increasing longline catch of these species was cause for concern by the small-vessel troll and handline fisheries that target them (Boggs(3)).

The fishing grounds of the Hawaii longline fishery expanded in the 1980's and 1990's. Hawaii fishermen interviewed in 1982 reported that they had to fish farther away from port in order to make good catches (Hawaii Opinion(8)). In 1986 Hawaii longliners began exploring fishing grounds up to 800 n.mi. from the main Hawaiian Islands, and distant-water fishing is becoming more common in the 1990's. Logbook data from the first quarter of 1991 indicate that over half of longline sets were more than 50 n.mi. away from the main Hawaiian Islands, and <2% of sets were made outside the EEZ (NMFS(12)).

Conflicts with other fisheries and interactions with protected species led to the exclusion of the longline fishery from nearshore waters in the 1990's. In early 1991 longline fishing was prohibited within a radius of 50 n.mi. off the NWHI (Dollar7) to prevent interactions between endangered Hawaiian monk seals, Monachus schauinslandi, and surface-fishing longliners that targeted aggregations of swordfish near those islands. In 1989 an informal agreement was negotiated between small-vessel fishermen and longline fishermen whereby longliners would keep >20 n.mi. from the coasts of the main Hawaiian Islands and >10 n.mi. from fish aggregating devices (FAD'S). Some vessels, especially subsequent entrants to the fishery, did not comply with the agreement. To mitigate conflicts between longliners and small-vessel troll and handline fishermen, the WPRFMC in mid-1991 established a buffer zone prohibiting longline fishing within a radius of 75 n.mi. off the coasts of Kauai and Oahu, or within a radius of 50 n.mi. off the coasts of Maui, Molokai, Lanai, Kahoolawe, and Hawaii (Dollar and Yoshimoto(6)).

The Troll Fishery

Troll and handline fisheries in Hawaii have not been studied as extensively as the longline fishery. Trolling involves towing lures or baited hooks behind a moving vessel, whereas handlining involves dangling baited hooks from a stationary or drifting vessel. The evolution and operation of the Hawaii troll fishery are poorly documented. Trolling with lures for pelagic species was a traditional Polynesian fishing method, and Hawaii has since been the site of important innovations in big-game troll fishing techniques (Rizzuto, 1983).

The troll fishery has several components: 1) a recreational-subsistence sector which is poorly differentiated from a part-time commercial sector, 2) a charter sector which is recreational for its patrons but commercial for the operators who sell the catch, 3) a part-time commercial sector, and 4) a full-time commercial sector. Most troll vessels are small (5-8 m, 15-25 ft in length), although charter boats range up to 18 m (59 ft). In the mid-1980's large (20-26 m, 65-85 ft) troll vessels transiting the Hawaii EEZ to fish for albacore, Thunnus alalunga, in the North Pacific participated briefly in the Hawaii troll fishery, and vessels from the lobster and bottomfish fisheries also participate intermittently in the Hawaii troll fishery. Troll fishing is conducted throughout the Hawaiian islands, generally within 20 n.mi. of shore.