marine fisheries in Southeast Asia
Trolling was a well established fishing method in many areas of Southeast Asia (particularly the Straits of Malacca, the Philippines and the western islands of Indonesia) by the nineteenth century with unbaited hooks, and a lure made from chicken feathers being towed behind sail-powered vessels to take small tunas and Spanish mackerel.
Like driftnetting (see Section VII), the Japanese that who were based in Singapore from the 1920s transformed the way in which trolling was conducted in the region and, in the 1930s, were taking both skipjack tuna (Katsuwonus pelamis) and bigeye tuna (Thunnus obesus) by trolling. Although the catches of these species were not large when compared with the driftnet fishery discussed in Section VII (about 100 tonnes were landed by trolling in 1932), the development is significant in that it appears that it introduced deepwater trolling for these species to the region. Skipjack inhabit deep coastal and oceanic water while bigeye tuna seldom appear at the surface, but are abundant at thermocline depths and therefore the landing of quantities of these species would indicate that the Japanese trollers had developed techniques to fish in deep offshore waters. In 1932, it was reported that these fishers, using motorized vessels, were working in areas remote from Singapore as far as the Anambas and Natuna Islands, the northern entrance to the Straits of Malacca, the Mergui Archipelago and the coasts of Borneo.
With the cessation of the activities of the Japanese troll fishers after the Second World War, trolling in the Straits of Malacca and other areas reverted to the operations of small, local, sail-powered vessels and further development of this sector was intimately tied to the rate of mechanization of the small-scale fishing fleet. As discussed in Section VII, in Malaysia and also in Singapore, this mechanization occurred rapidly during the 1950s and 1960s whereas in Indonesia and the Philippines, it occurred more slowly. As a result, a return to the use of mechanized vessels for trolling, and the exploitation of waters remote from the vessel’s home base, pioneered by the Japanese, occurred more quickly in Malaysia and Singapore than in other countries. Malaysia and Singapore, therefore, were able to sustain a small dedicated troll fishery, mainly for tuna, whereas in other areas trolling was often undertaken by small-scale fishers as an additional activity (often as they made their way to and from fishing grounds) to demersal hand-lining, gillnetting and other methods. In no area, however, was trolling a dominant activity.
In the Philippines, the development in 1975 of a fish aggregating device, locally known as a payaw, impacted significantly not only on the purse seine industry (see Section IV) but also on fishers who were taking tuna by hand-trolling. The tuna payaw (see Section IV) was a larger version of a similar lure that inshore fishers had traditionally used for small pelagic species, except the tuna payaw was placed between 35 and 110 km offshore, about 11 km apart from each other and in waters up to 3000 m deep. The rafts were “harvested” every 5 or 6 days. The cooperation between the two groups of fishers was significant with trollers and hand-line fishers targeting the larger tuna species that were attracted by the smaller prey fish but which swam at depths out of reach of the purse seine net. The hand-line and troll fishers watched over the payaw in return for the privilege of fishing there. This combination of purse seine and hand-line catches brought about a spectacular increase in tuna catches in the Philippines, which rose from 23000 tonnes in 1973 to 220000 tonnes in 1977.
Apart from this positive interaction between purse seine and troll fishers, the development of the tuna purse seine industry in the region (and, to a lesser extent, the pole-and-line fishery) also impacted negatively on vessels that were using trolling to take tunas. As the appetite of Thailand’s tuna canneries grew through the 1980s and the Thai purse seine fleet moved into new waters to meet the demand of the canneries, the total catch by the Thai fleet of small tuna species suitable for canning jumped from 20000 tonnes in 1981 to 170000 tonnes in 1992, but then, as they ran out of new areas to exploit, the catch began to decline. One of the impacts of this intensified fishing on small tunas by the Thai trawlers was that catches by Malaysian trollers operating off the east coast of the Malaysian Peninsula collapsed.
Trolling, like driftnetting, remains primarily an activity of the small-scale fisheries sector in Southeast Asia, particularly in Indonesia, Malaysia and the Philippines. However, unlike driftnetting, trolling for tuna and other pelagic species is generally undertaken as an adjunct, and often opportunistic, activity to other fishing operations. Because of this, and because of its relative small importance in most areas, statistics specific to this fishery are usually not available.