marine fisheries in Southeast Asia

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V. Purse seining

Although simple purse seining for pelagic species had been carried out in the region since the nineteenth century, the impetus for the development of an industrial-scale purse seine industry was, perversely, often the serial declines in a number of areas of demersal fish species which were taken by trawl fishing, which has been discussed above. In many cases, which will be further elaborated below, declining demersal fish stocks stimulated the search for new fisheries and, with mechanized vessels available, purse seining of pelagic fisheries was an obvious choice.

In the nineteenth century, various surrounding nets came to be used like purse seines, with the ability to close the lower end of the net by pulling a rope that passed through lead rings hanging from the lower edge of the net. Such nets were used, for example, in the Mollucas to catch a variety of pelagic fish and were often used in conjunction with fish aggregating devices, locally known as rumpon. In Cebu, fishers modified traditional floating nets to act as purse seines and these were extensively used by the 1930s to take flying fish. In the Philippines, a traditional purse-shaped net known as sapyaw was used prior to the 1920s to take large quantities of Sardinella although this net did not have a closing mechanism and needed to be positioned beneath the fish school, rather than surrounding them. After the 1920s, some operators in the Philippines adopted a net locally known as a kubkuban which was a small purse seine net (240 m long, 20 to 40 m deep and with a very large mesh) operated from a single large double-outrigger vessel. Because of the large mesh, larger pelagics such as mackerel were targeted.

By the early 1900s, sail-powered Chinese junks based on Hainan Island and on the Chinese mainland were operating purse seine nets (as well as trawl nets) in the Gulf of Tonkin. In 1910, between 600 and 700 such junks paid for a fishing permit at Cac Ba Island and many others were apparently fishing illegally. Butcher (2004) estimates that these vessels took 20000–25000 tonnes of prepared fish back to their home ports annually . Similar vessels (operated by Chinese from Hainan and each supported by three smaller tenders) were later used to develop purse seining in the Gulf of Thailand and also for Indian mackerel in Malayan waters in the Straits of Malacca during the 1930s, using nets that were about 310 m long, 50 m deep and with a 1.27 cm. Contemporary records show that catches varied enormously, and ranged from about 300 kg to 12 tonnes in a single haul.

A dramatic development occurred in the Straits of Malacca fishery in 1937 with the introduction of motorized vessels in place of the sail-powered junks. As a result of this development, landings of Indian mackerel at Pangkor increased dramatically, rising from 860 tonnes in 1931 to 5700 tonnes in 1938. The success of the venture stimulated local Malays to also begin purse seining, although the nets they used had larger mesh sizes than those of the Chinese purse seiners to enable them to be handled from their existing vessels. This resulted in landings of larger size mackerel, including, it is presumed, of Spanish mackerel.

Although developments of these traditional fishing methods resulted in increased landings, the increases were modest when compared with the dramatic increase in demand for fish and fish products, the increase in production from both aquaculture and from the developing trawling industry, and the increase in imports of fish products.

By the late 1960s, however, there were emerging problems with the large number of trawlers that were operating in areas such as the Gulf of Thailand and vessels were looking for new trawl grounds in the region. Drastic declines in trawl catch rates in the Gulf of Thailand and soaring oil prices prompted fishers to either modify existing vessels or have new vessels built for taking pelagic species, instead of trawl species. There were large stocks of pelagic species in the Gulf (particularly Indian mackerel) and methods such as purse seining required much less fuel than trawling. The total pelagic catch in the Gulf of Thailand therefore increased dramatically from 63000 tonnes in 1971 to 480000 tonnes in 1977, a result not only of an increasing number of purse seine vessels but also because of the use of light lures and the move to new fishing areas within the Gulf. This latter factor resulted in the landing of species such as scads and sardines that previously had not been a significant part of the pelagic catch.

Also, during the 1970s and early 1980s, the Government of Thailand promoted the development of a canning industry by encouraging foreign investment. The first tuna cannery was established in 1972 as a joint venture between an Australian company (Safcol Holdings) and Thai and Hong Kong investors and by 1983 there were 30–35 canneries in operation. This demand for tuna from the canneries led to purse seine vessels targeting the abundant stock of small tuna such as longtail (Thunnus tongil), kawakawa (Euthynnus affinis) and frigate (Auxis thazard) tuna. However, the fleet by 1991 had to rely on tuna catches from foreign waters (including Malaysia and the Natuna Islands) since the stocks in the Gulf of Thailand had diminished significantly. The development of the canning, particularly tuna canning, industry in Thailand during the 1980s (which made Thailand the world’s largest exporter of fish products by 1989, with 51 percent of global exports) was so rapid that canning capacity outstripped the ability of the fleet to supply raw product. This resulted not only in the Thai purse seine fleet seeking additional supplies in other waters of Southeast Asia, but, perhaps more importantly, also led to a rapid rise in the imports of frozen raw tuna, and other fish, for their canneries. By 1991, 79 percent of the 630000 tonnes of tuna that was canned in Thailand was derived from imported raw product. This demand for raw tuna for the Thai canneries therefore helped, in large part, to drive the development of tuna industries in other countries of the region, particularly the Philippines. The vast majority of this imported tuna originated from purse seine operations throughout the region, and, although a small quantity of tuna from pole-and-line and longline vessels was supplied to the Thai canneries, much of the tuna from these fisheries increasingly went to the Japanese sashimi market (see Section VI below).

As the fishery in the Gulf of Thailand developed without significant regulation, overexploitation of some pelagic fish species in the Gulf became evident and total landings in the Gulf fell steadily to 290000 tonnes in 1980.

In Indonesia, the development of the purse seine fishery was also influenced by the development, and subsequent problems with, the industrial trawl fishery. Although landings of pelagic species had been increasing substantially since the early 1900s (reaching 154000 tonnes by 1950 and 620000 tonnes by 1978 as both Chinese and Indonesian-owned purse seine vessels supplied newly built canneries and became the dominant fishing gear in Indonesia), the ban on trawl fishing in the 1980s accelerated the development of the purse seine fishery, particularly in the Java Sea. The Government, when banning trawling in the western part of the country, provided financial incentives for vessels to convert to purse seining, with the result that the number of purse seiners increased from an average of 810 during the period 1975–79 to 2100 in 1984–87. At this time, the larger purse seiners extended their operations into the eastern part of the Java Sea, with the result that landings by the Java Sea purse seine fleet increased from 49000 tonnes in 1975–79 to 140000 tonnes in 1984–87. After 1985, total landings (as well as annual landings per vessel) fell significantly, a result of overexploitation of the major species, particularly the small pelagics. Fortunately, the price of these fish increased at this time which enabled the purse seine fleet not only to survive economically but also expand to new areas in the southern part of the Makassar Strait and the waters between the Malay Peninsula and Borneo. The purse seiners also improved their technology, using light to attract fish and hence increase their efficiency. However, by 1995, total catches of pelagic species in the Java Sea had stagnated at around 150000 tonnes, roughly the same level as the early 1980s.

The catch by industrial purse seine vessels accelerated again after 1995, reaching 8 percent of the total marine catch of Indonesia by 1997 (FAO, 2000) as the vessels continued the expansion of their area of operations into the eastern areas of Indonesia, a process that had begun in the 1980s. In total, small-scale purse seine operations and industrial purse seine vessels together contributed approximately 17.6 percent of total marine production in Indonesia in 1997 (FAO, 2000) with the majority of this still coming from the small-scale sector, which continues to dominate the industry. However, the larger industrial purse seine vessels contribute much more in terms of value of the catch than the small-scale sector because they focus on high-value species such as tuna and other large pelagics whereas the small-scale fishers concentrate on inshore small pelagics in the western part of the country.

This expansion of industrial purse seiners into eastern Indonesian waters has been supported by the increased development of infrastructure such as tuna canneries and ports which also provide services to foreign fishing vessels. Purse seine vessels in the west of Indonesia fish for small pelagic species and are concentrated primarily in the Java Sea, South China Sea, Malacca Strait and Mollucas Sea. In general, these seiners range from 10 to 30Gross Registered Tonnage (GRT)2 , although in the last decade larger ones have been built, exceeding 100GR T. Purse seine vessels operating in the east of the country tend to be larger vessels, in excess of 100 GRT.

During the late 1970s, Japanese purse seiners were also expanding their operations in Southeast Asia and, in 1980, at least 14 vessels were operating off the north coast of Irian Jaya and Papua New Guinea, each taking about 15 tonnes of fish per day. As part of this operation, the Japanese vessels also captured large quantities of tuna in and around Indonesian waters.

In the Philippines, the traditional kubkuban purse seine net, in use since the 1920s, has continued to be used by small-scale, inshore fishers to take mackerel. In addition, in the 1950s, large-scale purse seining was introduced to the Philippines, probably by American tuna seiners operating in the eastern Pacific. The introduction included the use of nylon nets and power blocks for hauling the net. As the new fishing method was taken up enthusiastically, with trawlers being converted to seiners and secondhand Japanese purse seine vessels being imported, the move to purse seining was further supported by government incentives and assistance from a United Nations Special Fund project in importing nylon nets and other equipment.

At first, the increasing number of purse seine vessels (there were already 48 operating by 1966) targeted small pelagic species but, because of the large quantities of fish being landed and the lack of onshore processing facilities to handle the catch, prices collapsed in the late 1960s. With this price collapse, together with warnings that increasing fishing on small pelagic species may lead to a reduction in the quantity of fish available, vessels began to turn their attention to tuna. By 1975, purse seining for tuna in the Philippines had increased dramatically, aided by the development of fish aggregating devices, locally called payaw, around which the purse seiners as well as handline fishers operated. The payaw is particularly effective for aggregating skipjack and yellowfin tuna. Recorded tuna landings in the Philippines exploded from about 23 000 tonnes in 1973 to 220000 tonnes in 1977 although statistics are imprecise because of factors such as unrecorded foreign catches and the practice of Filipino vessels selling their catch to foreign vessels at sea.

Since the late 1970s, catches from tuna purse seining in the waters of the Philippines have increased only slowly, with recorded landings reaching about 300000 tonnes by 1997 and 400000 tonnes by 2002. However , during this time, Filipino operators of tuna purse seiners have expanded their operations considerably to other areas in the Indian and Pacific Oceans and these increases in recorded landings partly reflect this expanded fishing area as well as the targeting of other, smaller tuna species. Purse seining remains, however, the most common form of commercial fishing gear in the Philippines with 61 percent of operators using this gear, 15.7 percent using ring-nets and 12.4 percent using bag nets (FAO, 2005a). By contrast, only 3.7 percent of small-scale fishers use the small traditional purse seine or kubkuban. The purse seines, ringnets and handlines usually account for over 80 percent of the annual tuna catch, with nearly half the commercial tuna catch in 1995 taken by purse seine.

In addition to tuna, commercial purse seiners target small pelagic species, particularly roundscad, sardines and Indian mackerel. Together, these small pelagic species accounted for 47 percent by weight of overall commercial landings in 2003 (FAO, 2005a) from all gear types with tunas comprising the remainder. However, the proportion derived only from purse seine operations has not been reported. Because of their lower value, the small pelagic species comprise a much smaller proportion by value of the total commercial catch.

The shift in emphasis in a number of countries such as Indonesia and the Philippines in the 1960s and 1970s from demersal trawling to purse seining of small pelagics and, later, tuna, has also prompted other countries of the region to examine purse seining. In Viet Nam, some purse seining was undertaken early in the twentieth century by Chinese junks operating in the Gulf of Tonkin, as noted above. However, Viet Nam has not developed its own offshore purse seine fleet to any great extent although small purse seine vessels have, for some decades, taken small pelagic species in inshore waters. Although the inshore fishery is dominated by small trawlers, the offshore fleet of some 20000 vessels includes only about 100 vessels (with engines of 400–500 horsepower) which have the capacity for deep-sea fishing. This fleet comprises either trawlers or purse seiners. Trawlers are used in waters 35–80 m deep in southeastern waters, whereas purse seiners fish pelagic species in deep waters, mainly off the central region. The estimated percentage of the total catch from major types of fishing gear (FAO, 2005b) are; trawling 30 percent, purse seine 26 percent, gillnet 18 percent, lift net 5 percent, longline 6 percent and others (fixed net, push-net etc.) 15 percent. However, the development of offshore fisheries (including purse seining for tuna) has been vigorously promoted by the Government and has been included in a recent long-term strategic plan for the fisheries sector (FAO/Fishcode, 2004).

The expansion of purse seining by Thai vessels in particular also impacted the waters of Cambodia. Although Cambodia has a traditional, small-scale purse seine fishery, which operates in inshore waters to take Indian mackerel and anchovies (FAO, 2005c) together with small quantities of tuna, it has not developed a national industrial-scale purse seine fleet. Foreign purse seine operations in the waters of Cambodia, using industrial scale vessels, has, however, long taken place, often by Thai and Japanese vessels and this currently includes illegal operations. No data are available on the number of vessels involved or their catches.

While small-scale purse seine fisheries have a long tradition in many countries of the region, the development of industrialized purse seine fisheries in Southeast Asia accelerated following the initial decline in demersal fish stocks in the late 1960s. This development led to a search for new fisheries and, most importantly, for employment for the vessels and crew that were engaged in demersal trawling. Subsequent support of the boatbuilding industry in several countries and the increase in oil price in the 1970s also added to the attractiveness of vessels moving into the purse seine fishery.

With the decline in small pelagic stocks and reduced prices, the purse seine vessels turned their attention to tuna fishing in the early 1970s, particularly in the Philippines where this development was assisted by the use of fish aggregating devices. In addition, most of the purse seine fleets expanded out of their national waters in search of tuna (and also, to a lesser extent, small pelagic species) and it was this expansion and the move to tuna fishing that supported continued expansion both of the purse seine fleet and their catches. However, since the purse seine fleets were operating both inside and outside their national waters (both legally and illegally) and landing their catch in various places, the statistics on landings, the place of capture and the number of vessels operating are notoriously unreliable.

While the expansion of the tuna fisheries (and, to a lesser extent, small pelagics) is still occurring in some areas, and countries such as Viet Nam are still looking to expand their industrial purse seine fleet, most stocks of small and large pelagic species within the national waters of countries of the region are considered to have reached their peak production. Examining the region’s large-scale marine ecosystems (LMEs), Sugiyama et al. (2004) concluded that small pelagic stocks in the region had either peaked or were fluctuating in all areas except within the Sulu-Celebes Sea, the Indonesian Sea and the South China Sea LMEs where they were still increasing while large pelagics had either peaked or were fluctuating in all areas except the South China Sea LME. They also noted that the small and large pelagic resources in all areas generally had peaked after the demersal stocks, which is consistent with the known development of the trawl and purse seine fisheries in the region.

In the Philippines, recent studies on pelagic fisheries indicate overfishing and declining catch per unit effort (CPUE). Exceptions are in lightly fished areas in waters off Palawan, parts of the country’s Pacific coast and some parts of Mindanao. Such findings are supported by an observed change in species composition, i.e. anchovies have partially replaced sardines, scads and mackerels in the catch, an indication of gradual stock collapse (Green et al., 2003).

Like the demersal resources, the potential for expanding landings of small and large pelagic species by purse seining in the region therefore appears limited and the challenge for national governments is to move to long-term control and management of their existing fishing fleets. There are some encouraging signs that this is happening. Several countries (e.g. Viet Nam and the Philippines) have recently introduced new fisheries laws and, in the Philippines, the Government has made a significant policy shift by introducing joint management mechanisms of the fisheries sector, involving both the central government and the municipalities, and the fishers, through Fisheries and Aquatic Resources Management Councils.

However, much remains to be done in bringing long-term, sustainable management to purse seine operations in the region.

2 GRT is a measure of the capacity of the vessel below the main deck and differs from weight measures of vessels, such as displacement tonnage. See footnote 3 for details of the units of measurement for vessels.

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