The Environmental Impact of Shrimp Aquaculture: Causes, Effects, and Mitigating Alternatives

Attracted by the demand for shrimp in the developed countries, shrimp aquaculture has expanded rapidly, mainly in the subtropical and tropical lowlands of America and Asia. This work provides a global review and viewpoint on the environmental impacts of shrimp aquaculture, considering the causes and effects of the siting and operation of shrimp ponds and abandonment of farm facilities. Additionally, mitigating alternatives are discussed. To date, approximately 1–1.5 million ha of coastal lowlands have been converted into shrimp ponds, comprising mainly salt flats, mangrove areas, marshes, and agricultural lands. The impact of shrimp farming of most concern is the destruction of mangroves and salt marshes for pond construction. Compatibility with other users, the presence of buffer zones, maintaining an acceptable balance between mangroves and shrimp pond area, improved pond design, reduction of water exchange, and an improved residence time of water, size and capacity to assimilate effluents of the water body, are examples of ways to mitigate the adverse effects. The use of mangroves and halophytes as biofilters of shrimp pond effluents offers an attractive tool for reducing the impact in those regions where mangrove wetlands and appropriate conditions for halophyte plantations exist. Healthy seed supply, good feed with the use of prophylactic agents (including probiotics), good water quality, and lower stocking densities are examples of actions suggested to control disease in shrimp farming. Finally, in the context of integrated management, research priorities are suggested.     

The Importance of Supratidal Habitats for Wintering Shorebirds and the Potential Impacts of Shrimp Aquaculture

Intensive black tiger shrimp (Penaeus monodon) aquaculture ponds have replaced significant areas of coastal wetlands throughout tropical Asia. Few studies have assessed potential impacts on avian foraging habitats. At Khao Sam Roi Yod National Park, Thailand, seminatural wetlands have been converted to either shrimp ponds or to salinization ponds that provide saline water for shrimp aquaculture. Although shorebirds cannot feed in aquaculture ponds, hypersaline ponds can provide productive foraging areas. Thus, the overall impact of the shrimp industry on shorebirds depends partly on the relative quality of the salt ponds compared to seminatural wetlands. In this study, we examined wintering shorebird use of tidal (N = 5 sites) and supratidal areas (four wetland sites, four salt pond sites) and compared the shorebird community (14 species), prey availability, profitability, and disturbance rates between wetlands and salt ponds. Two shorebird species fed in higher densities in wetlands, whereas seven species were more abundant in salt ponds. Large juvenile fish and dragonfly larvae were more abundant in wetlands, whereas there were more small Chironomid midge and fly larvae in salt ponds. We conclude that salt ponds might provide higher-quality foraging habitats compared to wetlands for small shorebirds species because of the abundance of small larvae. However, the shrimp aquaculture industry reduces habitat availability for shorebirds feeding on larger prey. This study demonstrates a comprehensive, multispecies approach to assess the impacts of a large-scale change in coastal habitats for wintering shorebirds.     

Marine shrimp aquaculture and natural resource degradation in Thailand

Rising demand for shrimp in the developed nations has helped to foster a dramatic growth in marine shrimp aquaculture, particularly in South America and South Asia. In Thailand, Marine shrimp aquaculture is now an important earmer of foreign exchange. The growth in Production has been achieved through the expansion of the culture area and the adoption of intensive production methods. The conversion of near-shore areas to shrimp culture, however, is proving to have many consequences that impinge on the environmental integrity of coastal areas. This paper reviews the development of Thailand's marine shrimp culture industry and examines the nature of the environmental impacts that are emerging. It then discusses the implications these have for rural poor and the long-term viability of the culture industry.     

“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     

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.     

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.     

Mangrove mapping in Ecuador: The impact of shrimp pond construction

A cooperative mangrove mapping project between the Ecuadorian Center for Remote Sensing (CLIRSEN) and the University of Delaware was begun in August 1982. The objectives of the project were to create historical maps of mangrove ecosystem extent and change, while transferring aerial photographic interpretation techniques to Ecuadorian personnel. The result of this cooperation was a series of three 125,000 scale maps of historical mangrove extent and change from 1966 to 1982 in the southern Gulf of Guayaquil. This multitemporal study showed a 16% decrease in mangrove extent and a 27% increase in shrimp pond development. If these rates of change prevail into the future, mangroves in Ecuador will reach parity with shrimp ponds in 1984 and completely disappear by mid-1990. Recognizing the significance of this loss to shellfish and fish production along the coast, Ecuadorian scientists at CLIRSEN have subsequently initiated a nationwide mangrove mapping program to create a historical base for future mangrove management strategies.     

Cumulative environmental impacts and integrated coastal management: the case of Xiamen, China

This paper examines the assessment of cumulative environmental impacts and the implementation of integrated coastal management within the harbour of Xiamen, China, an urban region in which the coastal zone is under increasing pressure as a result of very rapid economic growth. The first stage of analysis incorporates components of a cumulative effects assessment, including (a) identification of sources of environmental impacts, notably industrial expansion, port development, shipping, waste disposal, aquaculture and coastal construction, (b) selection of a set of valued ecosystem components, focusing on circulation and siltation, water quality, sediment, the benthic community, and mangrove forests, and (c) use of a set of key indicators to examine cumulative impacts arising from the aggregate of human activities. In the second stage of analysis, the paper describes and assesses the development of an institutional framework for integrated coastal management in Xiamen, one that combines policy and planning (including legislative and enforcement mechanisms) with scientific and monitoring mechanisms (including an innovative 'marine functional zoning' system). The paper concludes that the integrated coastal management framework in Xiamen has met all relevant requirements for 'integration' as laid out in the literature, and has explicitly incorporated consideration of cumulative impacts within its management and monitoring processes.     

Sustainability and Local People’s Participation in Coastal Aquaculture: Regional Differences and Historical Experiences in Sri Lanka and the Philippines

This article discusses environmental sustainability in aquaculture and its contribution to poverty alleviation, based on field studies in Sri Lanka and the Philippines. The aquaculture practices studied are the monoculture of the black tiger prawn (Penneaus monodon) and milkfish (Chanos chanos) and the polyculture of the two species together with the mud crab (Scylla serrata). Factors affecting economic viability, social equity and environmental impacts in aquaculture are discussed and used to illuminate local and regional differences between aquaculture in Sri Lanka and the Philippines. Findings indicate that the most significant difference is the level of participation by local people (i.e., people originating ≤10 km away from the farm location). In the Philippines, 84 % of the people involved in aquaculture are locals, whereas in Sri Lanka, 55% are outsiders. Whether differences between the two areas can be explained by analyzing regional conditions, which might have resulted in different aquaculture practices, is discussed. In Sri Lanka, semi-intensive shrimp monoculture is currently the most common practice, whereas in the Philippines, extensive shrimp/fish polyculture is more common. Previous studies, as well as fieldwork, indicate that extensive culture practices reduce environmental impacts and benefit local people more. Sustainability in aquaculture is, however, also dependent on the extent of mangrove conversion into ponds. As such, extensive and locally owned farms do not necessarily result in an all but sustainable situation. Keeping this in mind, it is discussed if extensive polyculture practices might result in a more sustainable aquaculture, both environmentally and socioeconomically.     

How is Shrimp Aquaculture Transforming Coastal Livelihoods and Lagoons in Estero Real,Nicaragua?: The Need to Integrate Social–Ecological Research and Ecosystem-Based Approaches

Ecosystem-based approaches to aquaculture integrate environmental concerns into planning. Social–ecological systems research can improve this approach by explicitly relating ecological and social dynamics of change at multiple scales. Doing so requires not only addressing direct effects of aquaculture but also considering indirect factors such as changes in livelihood strategies, governance dynamics, and power relations. We selected the community of Puerto Morazán, Nicaragua as a case study to demonstrate how the introduction of small-scale aquaculture radically transformed another key livelihood activity, lagoon shrimp fishing, and the effects that these changes have had on lagoons and the people that depend on them. We find that shrimp aquaculture played a key role in the collapse, in the 1990s, of an existing lagoon common-property management. Shrimp aquaculture-related capital enabled the adoption of a new fishing technique that not only degraded lagoons but also led to their gradual privatization. The existence of social ties between small-scale shrimp farmers and other community members mitigated the impacts of privatization, illustrating the importance of social capital. Since 2008, community members are seeking to communally manage the lagoons once again, in response to degraded environmental conditions and a consolidation of the shrimp industry at the expense of smaller actors. This research shows that shrimp aquaculture intersects with a complex set of drivers, affecting not only how ecosystems are managed but also how they are perceived and valued. Understanding these social–ecological dynamics is essential to implement realistic policies and management of mangrove ecosystems and address the needs of resource-dependent people.