Environment
Where Have The Tuna Gone?
Longline Fisheries Face Diminishing Catches
The last five years has seen unprecedented growth in the domestic longline tuna fisheries of the southwestern Pacific. Locally based fisheries have developed in Fiji, French Polynesia, Samoa, American Samoa, Tonga, New Caledonia and the Cook Islands. In 2002, these fisheries caught an estimated 30,000 tons of longline tuna, up by over 100 percent from 1997.
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Historically, foreign longline fleets fished many of these areas. However, the development of a locally-based fishery provides the opportunity for greater returns to be realized by regional nations and territories. These fisheries are becoming an increasingly important component of the local economies, generating foreign exchange earnings and creating employment at-sea and on-shore in processing, boat building, servicing and other related industries. In Samoa, for instance, the fisheries industry is the largest sector in the country's exports.
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A domestic fishery increases the responsibilities of the country for the management of the resource. A higher level of monitoring of the fishery is required to ensure that reliable information is available to be able to manage the fishery in a sustainable way. Tuna is a migratory species that does not recognize boundaries between countries, so the management objectives of individual countries need to coincide with the wider management objectives of the region.
Many countries are developing the capacity to monitor their own tuna fisheries. However, there are limited resources, both human and financial, within most fisheries departments of the region.
Many countries rely on considerable input from regional organizations, principally the SPC and Forum Fisheries Agency, for advice concerning management of the tuna resource. There have also been specific aid programs (AusAID) to develop and manage the tuna fishery in individual countries. However, as the local tuna industries mature, the resources available within country will also need to evolve to match the requirements for management of the fishery.
Longline fishing is hard work, with domestic vessels in these countries undertaking trips of about one to two weeks in duration. Each morning 300 to 3000 hooks are set along on a horizontal line spanning 10 - 60 km (6.2 - 37.2 miles). The gear is then left to soak and recovered during the afternoon and evening.
The catch is typically dominated by albacore tuna, with the remainder of the catch comprised of other tuna species (yellowfin and bigeye), billfish species (marlins and swordfish), sharks and other commercial species (mahi mahi, opah and wahoo). Catches will vary between areas and seasons and depending on the skill of the fisherman and crew.
Like any new business, many new entrants are attracted with the prospect of making a quick return. However, fishing is a risky business with high fixed (boat and insurance) and operating costs (fuel, bait and freight)-and variable returns. Catch rates are often high during the initial development of a fishery, although in most cases these are not sustained over the longer term. Fish prices are also sensitive to global trends in supply and demand and beyond the control of the domestic industry.
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Inevitably, many of the new entrants to the fishery will struggle and there is a high attrition rate, particularly among the smaller operators. These are the growing pains typical of a new industry, but they are exacerbated in the tuna industry by the variability in catch. Tuna are sensitive to the prevailing ocean conditions and catch rates normally vary considerably between seasons.
Over the last year, many of the domestic fisheries have experienced very low catch rates, particularly for albacore. There has been growing concern among fishermen about the state of the fishery and the possible impact of increased longline fishing in the region.
This has been in contrast with the relatively optimistic assessments of the tuna stocks undertaken by the Oceanic Fisheries Program of SPC. A recent meeting of the Standing Committee on Tuna and Billfish, a forum established to review scientific advice from the tuna fisheries, concluded that the current level of regional catch from the albacore fishery was sustainable. However, in some areas, the level of fishing may have reached a level that is depressing local catch rates and impacting on the economic viability of the fishery.
Further analysis of catch rates from the longline fishery has also revealed a strong link with prevailing oceanographic conditions. Catch rates of albacore are generally higher in areas of high primary productivity (green water) and related to broad scale oceanic features (fronts) where there is a marked difference in sea temperature and productivity between two masses of water. These features tend to concentrate tuna, resulting in increased catch rates. The strength of these ocean features varies between seasons and location, explaining some of the variations observed in longline catch rates through the region.
The recent low catch rates of albacore appear related to weaker oceanic conditions throughout the subequatorial region where these fisheries operate. On a broader scale, these effects are likely to be influenced by the La Niña-El Niño cycle, so the recent low catches may represent the lower extreme of the normal longer-term fluctuations in fishing performance.
On a more positive note, it appears that catch rates in many areas have been recovering over the last few months as more normal oceanographic conditions return to the region.
