SUNS 4313 Friday 30 October 1998
ENVIRONMENT: FISH FARMS CRITICISED
Washington Oct. 30 (IPS/Danielle Knight) -- Fish farming, once heralded as an ecologically-sound alternative to ocean fishing, actually increases pressure on wild fisheries, pollutes ecosystems and may reduce the world's overall supply of fish, according to Science magazine.
"The boom in shrimp and salmon farming is hurting our oceans," said Rebecca Goldburg, a senior scientist with the Washington-based Environmental Defence Fund and co-author of a report published Friday in Science.
"While many fish stocks around the world have declined alarmingly, shrimp and salmon farming continues to expand - literally eating into wild fish populations."
The Science report, "Nature's Subsidies to Shrimp and Salmon Farming", said that fish farming - or aquaculture - destroys and pollutes coastal ecosystems that provide habitat for fish and other marine animals.
"Shrimp and salmon farms discharge untreated effluents laden with polluting nutrients, pesticides, and other chemicals directly into ecologically fragile coastal waters," said Goldburg.
"Creation of coastal shrimp ponds destroys mangrove forests and other wetlands that are crucial to the health of ocean fisheries."
As recently as the early 1980s, almost all fish - including shrimp and salmon - were caught in the ocean or other natural ecosystems, like lakes or streams.
Now, fish farms supply almost half of the salmon and about a quarter of the shrimp consumed worldwide, said the scientific researchers who wrote the Science report. In the United States, such farms supply about a third of the salmon and half the shrimp consumed.
Most farmed shrimp is produced in developing countries is Asia and Latin America and is exported to industrialised countries, said the report. Salmon, on the other hand, is grown and consumed primarily in industrialised countries - led by the United States, Canada and Norway.
As the world's oceans fisheries become degraded and severely threatened by overfishing and poor management, it has been commonly assumed that fish farming would relieve pressure on these wild stocks.
For fish species raised as carnivores, such as the popular shrimp and salmon, the opposite may be true, said Goldberg. Since shrimp and salmon are raised on fish caught from the wild, such aquaculture actually ends up depleting rather than augmenting fishery resources.
"On the farm, shrimp and salmon are fed a diet containing large quantities of wild-caught fish," said Goldburg. "For example, 2.8 pounds of wild-caught fish are required to produce one pound of farmed salmon."
"Farm-raising salmon is like farm-raising tigers," she said. "They will always eat more flesh that they produce."
The European salmon farming industry, for example, required a marine support area for feed estimated at 40,000 to 50,000 times the area of cultivation and equivalent to about 90 percent of the primary production of the fishing areas of the North Sea.
The increasingly large scale of fish farming industries, combined with other human activities, also placed demands on coastal ecosystems, said the report.
"Conversion of coastal ecosystems to aquaculture ponds destroys nursery areas that support ocean fisheries," it said. "Fish farming degrades coastal waters through discharge of nutrients and chemicals, and it disrupts coastal ecosystems by the introduction of exotic or non-native species."
Chemical and biological pollution from large shrimp farms in Asia have often resulted in the death of the shrimp population of a particular farm. The expansion of such farms has seriously threatened the already endangered mangrove ecosystems, it says.
Environmental degradation from these shrimp farms has also resulted in the dislocation of poor coastal communities who depend on this habitat for food and livelihood.
The ocean's capacity to cope with these wastes and maintain its fish populations is being challenged by this growth in aquaculture, it said. The Nordic salmon farming industry discharges huge quantities of nitrogen and other chemicals into coastal that equals the amounts in untreated sewage from a population of several million people, said the researchers.
"Poor water quality and high stocking densities have facilitated outbreaks of salmon diseases and parasites that have caused large losses to salmon farms," said Science. "They problems have led salmon farmers to use antibiotics and pesticides, which also end up in coastal water."
But the ecological costs of fish farming remained hidden from consumers because the prices of such fish did not reflect environmental impacts. "Most consumers are not aware of the ecological costs of their shrimp cocktails and salmon steaks, and producers do not pay these costs," said Goldburg.
As long as the full environmental costs of feed and stock inputs, pollution, and coastal land degradation are not recognized on the market, said the report, ocean resources and fisheries will deteriorate further.
"Incentives provided through regulation, reduced financial subsidies, and altered trade policies are urgently needed to end environmental degradation by shrimp and salmon farming," Goldburg said.
Besides developing strong and enforceable fish-farming regulations in both developing and industrialised countries, the Science report also said countries should encourage production of fish other that shrimp and salmon that are fed diets containing little or no fishmeal.
The report also advocated changing world trade rules to allow countries to restrict the import of fish or shrimp raised in an ecologically harmful manner. Recently, a U.S. law that prohibits the import of
shrimp caught without using devices that protect endangered sea turtles was ruled by the Geneva-based World Trade Organisation as being contrary to international trade law.
"Changing the global trading system is a tall order, at least in the short run," the report acknowledged. "But, reorienting national policies immediately toward an ecologically, socially, and economically sustainable view of aquaculture is both feasible and necessary."