Shrimp's Success Hurts Asian Environment, Group Says
Scientists say that, in addition to supporting a huge diversity of plant and animal life, mangroves perform many vital functions:
Mangroves guard against coastal erosion;
act as bulwarks to tropical storms;
regulate levels of soil salinity; and
act as refuges and nursery areas for many different fish, crustaceans, and shellfish traditionally harvested by local communities.
Shrimp farm development can damage other coastal habitats, including salt marshes and freshwater wetlands, according to the foundation report.
The environmental nonprofit says organic waste from shrimp farms is blamed for smothering coral reefs and sea grass beds. In Thailand alone, shrimp farms discharge up to 1.3 billion cubic meters (340 billion gallons) of effluent annually, according to past studies.
The nonprofit's report also highlights concerns over the levels of antibiotics, disinfectants, fertilizers, pesticides, and other chemicals used by shrimp farmers to maximize profits and combat disease.
Annabelle Aish, a marine researcher with the Environmental Justice Foundation, said: "Fertilizers can cause nutrient enrichment and eutrophication [aquatic plant blooms that deplete oxygen levels] of fresh and coastal waters, while pesticides are often highly toxic to aquatic wildlife which can lead to bioaccumulation in the food chain."
"Antibiotics, which are often heavily and inappropriately used due to fears of disease, affect natural bacterial activity and can cause development of antibiotic-resistant pathogens," Aish added. "These impacts are exacerbated by the removal of mangroves and other wetlands, which act as filters of pollutants."
In the case of the widely used antibiotic oxytetracycline, scientists say around 95 percent of this nonbiodegradable chemical finds its way into the wider environment.
A report by the American Society of Microbiology in 1995 singled out the use of antibiotics in aquaculture as potentially a leading cause of the evolution of antibiotic-resistant bacteria in humans.
A recent study in Thailand by Swedish-based scientists found that 77 percent of bacteria in farmed shrimp were resistant to one or more antibiotics.
The Environmental Justice Foundation report also noted that increased demand for warm-water shrimp species in the West has prompted a shift toward a "slash and burn" style of aquaculture, because the networks of large, human-made ponds have to be abandoned after five or six years due to disease and poor water quality.
In the upper Gulf of Thailand alone, 40,000 hectares (99,000 acres) of farms were abandoned by 2000, with 90 percent of shrimp farmers left out of business, according to a Thailand Development Research Institute report.
Instead of intensive production systems, the Environmental Justice Foundation says other, more sustainable forms of shrimp farming, such as polyculture, should be encouraged.
"Polyculture" refers to a traditional farming method in Asia where several species are farmed together in the same water, helping to insure against the risk of disease and changing market conditions. In the Philippines, for example, fish, shrimp, and shellfish are farmed among mangroves in a system known as tumpang sari.
Another option, says Aish, are certified organic farms which "are obliged to use nontoxic inorganic compounds, rather than chemical pesticides, fertilizers, and antibiotics," she said. "[Organic farms] also make an effort to reduce their reliance on fish meal [for fertilizer or animal food]."
Yet there may be financial reasons why less intensive forms of shrimp farming are not practical, said Rohana Subasinghe, a senior fisheries officer with the UN Food and Agriculture Organization's Inland Water and Aquaculture Service.
"Certification is not necessarily a silver bullet," said Subasinghe. "It means costsand for small fish and shrimp farmers, those costs may be prohibitive," Subasinghe said. "Without doing something to address that [added expense], you could see thousands of small-scale families pushed right out of business in the developing world."
"Another challenge is coming up with a coherent set of standards that make sense on a global scale," Subasinghe said, noting that this is no easy task. "Especially when standards are set in rich importing countries and must be met by poor exporting countries with very limited technical and financial resources."
Aish, the Environmental Justice Foundation marine researcher, advises consumers to "cut down on eating shrimp, or cut it out altogetherunless you can be assured it comes from sustainable sources."
"Consumers have considerable power and responsibility," she said. "With their help, unsustainable methods of shrimp farming can begin to be eradicated."
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