“Low-Salt” Shrimp Aquaculture in Thailand: Goodbye Coastline, Hello Khon Kaen!

/ Intensive shrimp culture has been confined to relatively narrow bands of land along the seashores of tropical developing nations due to the need for large volumes of saltwater for water exchange during the culture period. Recent developments in Thailand suggest, however, that this close association could soon be a thing of the past. Large numbers of Thai farmers are adopting low-salinity culture systems that rely upon sea or salt pan water that is trucked inland. This development greatly increases the potential for establishing shrimp cultivation much further from the coast than previously believed possible. The migration of intensive shrimp farming into freshwater environments, however, raises serious concerns over the disposal of pond effluents and the impact of saltwater intrusion on surrounding agricultural activities. In the absence of effective government regulation of the expansion and operation of the shrimp culture industry, supporting local nongovernmental organizations (NGOs) and community initiatives may be the only means of minimizing the negative impacts of shrimp farming on rural communities.KEY WORDS: Aquaculture; Shrimp; Salinity; Thailand     

Toward Improved Environmental and Social Management of Indian Shrimp Farming*

In the last decade, Indian shrimp aquaculture production tripled from 30,000 tons (1990) to 102,000 tons (1999). This fast development, combined with a lack of adequate planning and regulation, caused a number of environmental problems and social conflicts, including conversion of mangroves, water pollution, and salinization of drinking water wells. Because of the significant investments made in shrimp culture and the size of the environmental and social impacts, the formulation of a regulatory framework for shrimp aquaculture has been subject to an intensive debate between the aquaculture and the environmental lobbies. Following an order from the Supreme Court (1996), the Aquaculture Authority was established and a regulatory and institutional framework for the shrimp aquaculture sector has been set up. However, implementation of the system is still defective, and there is an urgent need for improvement. Farmers are increasingly able to prevent the devastating white spot disease in shrimps, and in the absence of proper planning and regulation, further expansion of shrimp production could result in significant additional environmental and social costs. The environmental and social management of Indian shrimp farming can be improved through a mix of policy measures, including strengthening of the license system, more effective enforcement of regulations, the use of economic incentives, and increased monitoring of environmental and social impacts.     

Economic Valuation of a Mangrove Ecosystem Threatened by Shrimp Aquaculture in Sri Lanka

Mangrove ecosystems in Sri Lanka are increasingly under threat from development projects, especially aquaculture. An economic assessment is presented for a relatively large (42 ha) shrimp culture development proposed for the Rekawa Lagoon system in the south of Sri Lanka, which involved an extended cost–benefit analysis of the proposal and an estimate of the “total economic value” (TEV) of a mangrove ecosystem. The analysis revealed that the internal benefits of developing the shrimp farm are higher than the internal costs in the ratio of 1.5:1. However, when the wider environmental impacts are more comprehensively evaluated, the external benefits are much lower than the external costs in a ratio that ranges between 1:6 and 1:11. In areas like Rekawa, where agriculture and fisheries are widely practiced at subsistence levels, shrimp aquaculture developments have disproportionately large impacts on traditional livelihoods and social welfare. Thus, although the analysis retains considerable uncertainties, more explicit costing of the environmental services provided by mangrove ecosystems demonstrates that low intensity, but sustainable, harvesting has far greater long-term value to local stakeholders and the wider community than large shrimp aquaculture developments.     

Environmental Issues in Brackish Water Shrimp Aquaculture in Sri Lanka

Shrimp exports are one of Sri Lanka's major foreign exchange earners and account for 40%–50% of total aquaculture exports. There has been a recent and rapid expansion of the industry in the Northwestern Province (NWP) of Sri Lanka but the industry has suffered from disease outbreaks and environmental problems. Currently, shrimp farms cover nearly 3000 ha of the coastal area of the NWP. The environmental impacts of shrimp cultivation in general are well known and numerous research studies have been done. However, little work has been carried out in Sri Lanka. This study provides some necessary background to brackish water shrimp aquaculture in Sri Lanka. It focuses briefly on the development of shrimp aquaculture and the current status of the industry. Emphasis is placed on two broader aspects—impacts on the existing wetland ecosystem and on the environment. These impacts are presumed to be the main causes hindering the growth of the industry and raising widespread public protest. Current ecosystem and environmental management practices are discussed. Finally, strategic issues for management and sustainable growth are discussed.