The longline fishery continues to account for around 10–13% of the total WCPFC–CA catch, but rivals the much larger purse seine catch in landed value. It provides the longest time series of catch estimates for the WCP–CA, with estimates available since the early 1950s. The total number of vessels involved in the fishery has generally fluctuated between 3,500 and 5,500 for the last 30 years.
The fishery involves two main types of operation :
- large (typically >250 GRT) distant-water freezer vessels which undertake long voyages (months) and operate over large areas of the region. These vessels may target either tropical (yellowfin, bigeye tuna) or subtropical (albacore tuna) species. Voluntary reduction in vessel numbers by at least one fleet has occurred in recent years;
- smaller (typically <100 GRT) offshore vessels which are usually domestically-based, undertaking trips less than one month, with ice or chill capacity, and serving fresh or air-freight sashimi markets, or [albacore] canneries.
The following broad categories of longline fishery, based on type of operation, area fished and target species, are currently active in the WCPFC–CA :
- South Pacific offshore albacore fishery comprises Pacific-Islands domestic “offshore” vessels, such as those from American Samoa, Cook Islands, Fiji, French Polynesia, New Caledonia, Samoa, Solomon Islands, Tonga and Vanuatu; these fleets mainly operate in subtropical waters, with albacore the main species taken.
- Tropical offshore bigeye/yellowfin-target fishery includes “offshore” sashimi longliners from Chinese-Taipei, based in Micronesia, Guam, Philippines and Chinese-Taipei, mainland Chinese vessels based in Micronesia, and domestic fleets based in Indonesia, Micronesian countries, Philippines, PNG, the Solomon Islands and Vietnam.
- Tropical distant-water bigeye/yellowfin-target fishery comprises “distant-water” vessels from Japan, Korea, Chinese-Taipei, mainland China and Vanuatu. These vessels primarily operate in the eastern tropical waters of the WCP–CA (and into the EPO), targeting bigeye and yellowfin tuna for the frozen sashimi market.
- South Pacific distant-water albacore fishery comprises “distant-water” vessels from Chinese-Taipei, mainland China and Vanuatu operating in the south Pacific, generally below 20°S, targeting albacore tuna destined for canneries.
- Domestic fisheries in the sub-tropical and temperate WCP–CA comprise vessels targeting different species within the same fleet depending on market, season and/or area. These fleets include the domestic fisheries of Australia, Japan, New Zealand and Hawaii. For example, the Hawaiian longline fleet has a component that targets swordfish and another that targets bigeye tuna.
- South Pacific distant-water swordfish fishery is a relatively new fishery and comprises “distant-water” vessels from Spain.
- North Pacific distant-water albacore and swordfish fisheries mainly comprise “distant-water” vessels from Japan (swordfish and albacore), Chinese-Taipei (albacore only) and Vanuatu (albacore only).
Additionally, small vessels in Indonesia, Philippines and more recently in Papua New Guinea target yellowfin by handlining and small vertical longlines, usually around the numerous arrays of anchored FADs in home waters . The commercial handline fleets target large yellowfin tuna which comprise the majority of the overall catch (> 90%).
The WCPFC–CA longline tuna catch steadily increased from the early years of the fishery (i.e. the early 1950s) to 1980, but declined in the five years after (Figure 9). Since 1984, catches steadily increased over the next 15 years until the late 1990s, when catch levels were again similar to 1980. Annual catches in the longline fishery since 2000 have been amongst the highest ever, but the composition of the catch in recent years (e.g. ALB–30%; BET–38%; YFT–30%; SKJ–2% in 2008) differs considerably from the period of the late 1970s and early 1980s, when yellowfin tuna were the main target species (e.g. ALB–19%; BET–27%; YFT–54% in 1980).
Longline catches since the record catch in 2004 have declined somewhat, due to a combination of reduced effort and catch-per-unit-effort (Figure 9). The distribution of catches is widespread throughout the tropical and sub-tropical Pacific, which yellowfin and bigeye dominating catches in the equatorial zone, and albacore dominating at higher latitudes (Figure 10).
Figure 9. Longline catch by species.
Figure 10. Longline catch by species, 2007-2009.