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

Environmental Science Department, Lancaster University, Lancaster, LA1 4YQ, United Kingdom.
Environmental Management (Impact Factor: 1.72). 11/2005; 36(4):535-50. DOI: 10.1007/s00267-003-0286-9
Source: PubMed

ABSTRACT 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.

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    • "Many small-scale farmers took on farming, leading to an expansion of shrimp aquaculture. Small-scale farmers continued to farm within their community areas, while large and medium-scale farmers shifted from place to place by converting mangrove [26] and coconut cultivating lands into shrimp farms [27]. Low stocking densities of shrimp postlarvae (PL) in small-scale farms (7–12 PL/m 2 ) compared to that of large-and medium-scale farms (12–25 PL/m 2 ) cause less disease incidences in small-scale farms and also lower operation cost in small-scale farms than in other farms bring about high profit margins per unit area in small-scale farms [28]. "
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    ABSTRACT: Shrimp aquaculture in northwestern Sri Lanka shows co-management like features. To understand the reasons behind co-management and to identify the mechanisms by which co-management is carried out, the paper examines shrimp aquaculture operations in three coastal communities using a case study approach. Water from an interconnected lagoon system is the key input for shrimp ponds, but it is also the potential source of shrimp disease outbreaks that threaten all shrimp farms. Farmers try to prevent the spread of disease by co-operating to adjust the timing of water intake and wastewater release. This is done through a zonal crop calendar system which is developed and implemented by a vertically integrated institutional structure with three levels: sub-zonal/community, zonal, and national. Partnerships, overall sharing of power and authority, and learning-by-doing are key features of this collaborative management system. The case shows that adaptive co-management can develop through collaborative problem-solving over time, even in the absence of legal arrangements.
    Marine Policy 10/2015; 60. DOI:10.1016/j.marpol.2015.05.009 · 2.62 Impact Factor
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    • "c o m / l o c a t e / e c o l i n d negative environmental outcomes (Rosenberry, 1998; Páez-Osuna, 2001; EJF, 2003). However, the economic benefits of shrimp aquaculture should not be disregarded as added capital can boost the national economy, improve local livelihoods, and aid in rural development (Frankic and Hershner, 2003; Gunawardena and Rowan, 2005). Vietnam's aquaculture is poised to intensify as declared by Government Decision No. 21, 1998 and Government Decision No. 67, 1999 (EJF, 2003), encouraging aquaculture expansion at the private level, exposing mangrove wetlands to future pressures. "
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    ABSTRACT: Wetland valuation methods often apply monetary driven approaches that may undermine intrinsic ecosystem values. Utilizing a stated preference method, the study identified and mapped local stakeholder ecosystem service values between subsistence wetland and shrimp farmer groups in Can Gio, Vietnam. Through focus group choice experiments, ecosystem services correlating to unique price increments and cost/benefit tradeoffs between hypothetical intensive aquaculture developments and mangrove conservation scenarios were investigated. Selection outcomes exhibited strong values for ecosystem services maintained at the hypothetical natural state (core area pre-intervention 45%, post-intervention 55%; buffer zone pre-intervention 65%, post-intervention 73%). Few respondents selected the hypothetical intensive aquaculture development scenario (core area pre-intervention 18%, post-intervention 9%; buffer zone pre-intervention 12%, post-intervention 5%), and instead, most respondents avoided the costs and benefits of intensive aquaculture development in preference for maintaining natural ecosystem services. Group deliberations drew out a higher sense of altruism and responsiveness to intrinsic wetland values that superseded the potential economic gains of aquaculture developments, whereby certain ecosystem services were deemed economically unassociable and irreplaceable for both study groups. The qualitative results expose the difficulties in monetarily measuring ecosystem services, highlighting the need to incorporate approaches that integrate the intrinsic values attached to ecosystem services.
    Ecological Indicators 07/2014; 46. DOI:10.1016/j.ecolind.2014.06.012 · 3.44 Impact Factor
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    • "As a result, farming area expanded over the northwestern part of the country. Small-scale farmers conducted their operations within their community areas, while large and medium-scale farmers shifted from place to place by converting mangrove forests (Gunawardena and Rowan 2005) and coconut plantations into shrimp farms (Cattermoul and Devendra 2002). However, the expansion of aquaculture into the eastern part of the country was restricted due to the civil war that was taking place. "
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