Tuna Purse-Seining

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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

  1988 1995 2002 2003
Japan 39 33 35 34
USA 32 43 29 20
Korea, Republic of 23 30 28 27
Taiwan (Province of China) 1 42 41 38
China 0 0 3 4
Solomons 4 3 2 1
PNG 0 3 6 7
FSM 0 5 7 9
Marshalls 0 0 5 6
Kiribati 0 1 1 1
Vanuatu 0 2 11 15
NZ DW 0 0 4 4
Australia DW 3 0 0 0
Spain 0 0 1 1
Neth. Antilles 0 0 1 1
Panama 0 0 0 1
USSR 5 0 0 0
Philippines DW 9 13 23 22
Indonesia DW 3 0 0 0
TOTAL 119 175 197 191

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:

Figure 3: The shift in the purse seine fishing activity

  A: regular year (2001)  B: El Niño year (2002)

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