TUNA PURSE-SEINING

Primarily due to expanding Japanese tuna catches in the 1950s, the California-based pole-and-line fishery (almost 300 vessels) experienced severe financial difficulties. The fleet survived largely through technical innovations that led to the feasibility of using purse seine gear for capturing tuna. In the subsequent years nearly 100 California bait boats were converted to purse seiners and new tuna purse seiners were constructed. The technique later was taken up by Japanese tuna fishermen for use in temperate waters off Japan. By the late 1960s between 60 and 70 small Japanese tuna purse seine vessels (50 to 200 GRT) were fishing seasonally (Gillett, McCoy and Itano, 2002; Gillett and Lewis, 2003).

Tuna purse-seining in tropical waters was another matter. The characteristically clear water and deep thermocline in the equatorial Pacific create conditions unfavourable for purse-seining � the tuna schools tended to be smaller, faster-moving, and dive deeper than in the eastern Pacific or off Japan. The government of Japan and subsequently that of the United States of America sponsored many experimental purse-seining expeditions to the equatorial Pacific area. The Japanese persisted and were the first to have success. The main innovation was the pre-dawn setting of deep nets around logs in the area between Micronesia and Papua New Guinea. By the late 1970s there were several fully commercial Japanese and American purse seine operations in the western equatorial area of the Pacific Islands.

The number of purse seine vessels operating in the Pacific Islands increased rapidly during the early 1980s. The USA purse seine fleet moved in quickly from the eastern Pacific due to the very strong El Niño event of 1982�83 and pressure to reduce dolphin mortality in their traditional fishing grounds. In 1983, 62 USA seiners caught 179 000 tonnes of tuna in the Pacific Islands area. During the period from the mid-1980s to 2003 the regional purse seine fleet expanded, albeit at a slower rate, and the national composition of the fleet became more diverse (Table 1).

Table 1: Number of active purse seine vessels in the Pacific Islands

Source: Gillett and Lewis (2003); DW = distant water, as opposed to domestic fishing.

One of the major purse seine operational patterns concerns disposal of the catch. The Republic of Korea, Taiwan (Province of China) and China transship their catch onto to large carrier vessels, and do so mostly in ports of the Pacific Island countries. The Japanese return all catch to Japan. The USA fleet and most vessels from the Philippines that operate in the Pacific Islands offload the bulk of their catch directly to canneries.

The region�s first conservation-oriented management move in the tuna fisheries was the Palau Agreement for the Management of the Western Pacific Purse Seine Fishery. The Palau Arrangement was signed in October 1992 by Federated States of Micronesia, Marshall Islands, Nauru, Palau and Tuvalu. Kiribati and Papua New Guinea signed the following year. The arrangement places a ceiling on the number of purse seine licenses that can be issued by the seven Pacific Island countries party to the agreement. The limit was originally set at 164 vessels and progressively increased to the present 205. For several years there has been discussion of modifying the Palau Arrangement so that purse seine vessel fishing days (rather than vessel numbers) are used as the basis for management.

Major events affecting purse-seining in the Pacific Islands region during the last two decades have been:

• Strong El Niño events, especially that of 1982�83, resulted in good purse seine fishing in the Pacific Islands and the opposite in the eastern Pacific. In general, during El Niño year the purse seine fishery moves to the east of its normal location between Papua New Guinea and the Federated States of Micronesia (Figure 3).


Figure 3: The shift in the purse seine fishing activity
A: regular year (2001) B: El Niño year (2002)

• The USA Multilateral Tuna Treaty was signed in 1987 and came into force in 1988. Since that time, the USA purse seine fleet has enjoyed access to most of the region except closed areas in some EEZs.
• In 1999 the price of skipjack on the world market dipped below US$400 per tonne for the first time since purse seining in the Pacific Islands area began, causing many seiners to cease operation and some to go into bankruptcy.
• There has been a general increase in the proportion of tuna caught by purse-seining relative to that by longline or pole-and-line. About 80 percent of the tuna in the region is presently caught by this gear.

Figure 3: The shift in the purse seine fishing activity
A: regular year (2001)	B: El Niño year (2002)

• The USA Multilateral Tuna Treaty was signed in 1987 and came into force in 1988. Since that time, the USA purse seine fleet has enjoyed access to most of the region except closed areas in some EEZs.
• In 1999 the price of skipjack on the world market dipped below US$400 per tonne for the first time since purse seining in the Pacific Islands area began, causing many seiners to cease operation and some to go into bankruptcy.
• There has been a general increase in the proportion of tuna caught by purse-seining relative to that by longline or pole-and-line. About 80 percent of the tuna in the region is presently caught by this gear.