A little bit of shrimp farming is OK, environment economists say
Journal Watch Online 17 Jan 08;
The choice between total devastation and total conservation of mangroves is a false one, according to analysis published today in Science.
With a team of colleagues, Edward Barbier, a professor of economics at the University of Wyoming, studied the effects of conversion to shrimp aquaculture on a 10 km stretch of Thailand’s mangrove.
Because mangroves play such a pivotal role in coastal protection from storms, hurricanes and tsunamis, their economic value is high (compared to the potential cost of disaster recovery in their absence).
However, these benefits are only felt locally, whereas the profits from shrimp farms line pockets around the world.
Barbier’s group found that a small amount – no more than 20 percent – of farming makes little difference to the protective powers of the mangrove: it’s only at higher levels of degradation that things start to bite.
Understanding the impact of shrimp farming properly could help conservation managers achieve a delicate balance between ecosystem protection and keeping the fat cats happy.
Source: Barbier EB, Koch EW, Silliman BR, Hacker SD, Wolanski E, Primavera J, Granek EF, Polasky S, Aswani S, Cramer LA, Stoms DM, Kennedy CJ, Bael D, Kappel CV, Perillo GME & Reed DJ (2008) Coastal ecosystem-based management with nonlinear ecological functions and values. Science DOI:
Ecosystem Based Management Not Enough to Reverse Coastal Habitat Decline
Newswise.com 17 Jan 08;
Newswise — Worldwide coastal ecosystems and habitats will continue to decline unless economists and ecologists work together to improve current methods to assess coastal ecosystem benefits, according to an article today in the global scientific journal, Science.
Edward B. Barbier, the John S. Bugas Professor of Economics at the University of Wyoming, is the lead author among 15 others on the subject (“Coastal ecosystem-based management with non-linear ecological functions and values.”)
Recent research indicates that global coastal population densities are nearly three times those of inland areas and are rapidly rising, Barbier says. As coastal and marine habitats come under more pressure from human exploitation, economists, ecologists and other scientists need to collaborate to improve the understanding of the myriad “benefits” lost through such overuse to better inform coastal and marine management decisions, he says.
“The long-term sustainability of these populations depends upon coastal ecosystems and the services they provide, such as storm buffering, fisheries production and enhanced water quality,” he adds. “To arrest coastal habitat decline, concerned international organizations and scientists are calling for a new approach.”
He says ecosystem-based management (EBM) is a way to reconcile the decline in vital coastal ecosystem services with continuing human development pressures. Barbier and his colleagues endorse the general need for coastal EBM, but their research indicates that strategy is “likely to fail” unless others, such as economists and ecologists, work together.
“Too often, poor ecological data lead to inaccurate valuation of these benefits, resulting frequently in an ‘all or none’ choice of either preserving or converting all coastal habitats to human use,” Barbier says. “This ‘all or none’ outcome is at odds with EBM strategies, which are trying to find acceptable compromises between conservation and development.”
To illustrate the importance of this dilemma, Barbier and his team focus on the key ecosystem service of coastal wetlands acting as “natural barriers” to the economic damages caused by frequent coastal storm events. In recent years, this critical “storm prevention” service of coastal habits -- such as mangroves and marshlands -- has received considerable attention caused through massive damages. Those were inflicted by the December 2004 Indian Ocean tsunami, the August 2005 Hurricane Katrina along the Gulf Coast and the November 2007 Cyclone Sidr in coastal Bangladesh.
From field studies of mangroves, salt marshes, seagrass beds, near shore coral reefs, and sand dunes, the study shows that the ability of these critical habitat to “attenuate” or break up, incoming storm surges and waves declines considerably as more habitat is lost.
Barbier’s research in Thailand demonstrates how mangroves successfully protect coastal regions.
“We show that by valuing correctly this ‘natural barrier’ service, the best land use is neither complete conversion of the mangroves to an alternative use, such as commercial shrimp aquaculture, nor preservation of all the mangrove forest,” he says. “Instead, the best coastal management policy is a mix of these development and conservation options. In fact, the outcome from our Thailand mangrove valuation example corresponds to ‘best practice’ guidelines for mangrove management in Asia, which recommend that ideal mangrove-pond ratios should not exceed 20 percent of the habitat area converted to ponds.”
