Cost-Benefit Analysis of Mangrove Conservation Versus Shrimp Aquaculture in Bintuni Bay and Mimika, Indonesia

This cost-benefit analysis (CBA) focused on two mangrove areas in the Papua and West Papua regions of eastern Indonesia: Bintuni Bay and Mimika. These sites were selected because of their global importance as large contiguous areas of mangroves with high productivity and biodiversity (Alongi 2007). The Bintuni site had a mangrove wood harvesting concession that has operated since 1988. The Mimika site was adjacent to a large mangrove area in the Asmat Regency.

The CBA considered two scenarios. The Business-as-usual (BAU) scenario assumed that the low, existing mangrove conversion rate of 0.05 percent per year would continue at both sites, leading to a 2.8 percent reduction in mangrove area over 50 years. Most of this mangrove conversion has been for human settlements and infrastructure, not aquaculture. The Alternative scenario assumed that an additional 0.75 percent of the mangrove area would be converted to shrimp aquaculture each year resulting in a 54 percent net reduction in the mangrove area over 100 years, after regrowth of abandoned aquaculture areas.

Information on the costs and benefits of activities supported by the mangroves (near-shore fishing, farming, hunting and gathering, wood harvesting, and collecting mangrove palm products for roofing materials, food, and beverages) was collected through a survey of 120 households in three villages at each of the two sites. Although mangroves are also important spawning and nursery areas for off-shore fisheries, no data were available to quantify these benefits.

The economic analysis also included the value of mangroves for carbon storage and reducing damage from cyclones and tsunamis. Carbon sequestration estimates were available for Bintuni Bay and Mimika. Since there was no history of cyclones or tsunamis in either of the study sites, the base case analysis assumed that that these events would not occur during the study period.