インドネシアにおけるノコギリガザミ漁業の現状と資源保全 : 南スラウェシ州とマルク州のノコギリガザミ漁を事例に

Abstract

With the increasing demand for mud crabs (Scylla spp.) in international markets, these crustaceans have emerged as important fishery resources in Indonesia since the early 1980s. As part of the effort to increase the production of mud crabs, the Indonesian government established a department to conduct research into various aspects of mud crab aquaculture techniques. However, mud crab aquaculture in the field is still dependent on natural seedlings collected from mangrove areas, because until recently cultured larval production from mud crabs was difficult, yielding low and inconsistent quantities. Mud crabs have a life cycle that depends on the mangrove ecosystem, and their resources are limited by the mangrove area. Decreases in mangrove area caused by the expansion of aquaculture ponds for increased mud crab production, and overfishing driven by increased market demand, are expected to have significant direct impacts on mud crab natural resources. However, in comparison with information on mud crab aquaculture techniques, there is a paucity of data on the actual state of mud crab fishing activities in response to the growing demands of the market. This study, carried out between 2009 and 2011, focuses on the state of mud crab fishing activities in three regions of Indonesia: Sinjai and Palopo in South Sulawesi Province, and Walirou Island in Maluku Province; Indonesia is one of the countries with a high production of mud crabs. The results show that it is difficult to apply intensive fishing methods to mud crab fisheries due to the physical structure of mangroves - and thus traditional fishing gear is still used, despite the increase in catch production since around 2000. Mud crab fishing can be easily done even with no special techniques, which provides a good opportunity as an income source for local people in coastal areas. However, mud crab fishery production showed a decreasing trend in Palopo and Sinjai between 2000 and 2010. This was due to increased fishing pressure, especially as immature mud crabs, which were not previously valuable to the market, came to be the targets of fishing efforts. Therefore, the imposition of size limits on crab purchases made by middlemen would be an effective management strategy for the conservation of mud crab resources.