Salmon And Shrimp Farming Said Harmful To World's Fish Supply
By Michael Kahn
WASHINGTON (Reuters) - Salmon and shrimp farming does not protect the world's lessening fish supply, as once thought, but actually reduces it because of feeding requirements and environmental damage, researchers said Thursday.
Scientists had thought fish farming, or aquaculture, could provide a valuable resource management tool and a steady food supply. But a new report indicates the booming shrimp and salmon industries actually damage the delicate balance of the seas.
"(The report) challenges the very common assumption that fish farming produces more fish for the world to eat," said Rebecca Goldburg, a biologist for the Environmental Defense Fund who worked on a special report published in the journal Science.
She and a team of international researchers, including experts in aquaculture, ecology, and resource economics and policy, said the rapid growth of shrimp and salmon farming endangered the environment.
"The increasingly large scale of these industries, combined with other human activities, now places substantial demands on ocean ecosystems, which in turn result in the demise of fisheries and biological diversity," they wrote.
They said global aquaculture production more than doubled in weight and value between 1986 and 1996 to account for more than one-quarter of all fish consumed by humans.
But farmed shrimp and salmon are fed other fish in the form of fish meal and fish oil. And it is an inefficient process.
For instance, said Jane Lubchenco, a marine ecologist at Oregon State University who worked on the study, it takes 3 pounds of wild-caught fish to produce enough protein for 1 pound of salmon.
Million of tons of fish are already caught on the open seas to supply the fish farms, and these numbers will only increase, the experts say.
"So it's a losing proposition if what you are trying to do is decrease the pressure on wild-caught fish," Lubchenco said.
The discharge of waste and pesticides from farm ponds into the open ocean is another problem, because it depletes natural fisheries by destroying nursery areas supporting wild fish and other marine species, Lubchenco said.
Shrimp and salmon are farmed in coastal areas where building ponds can damage the natural environment. Shrimp farms are often built in fragile mangrove forests -- a practice that, combined with coastal development, has already caused 50 percent of mangrove habitat to disappear, Lubchenco said.
Mangrove forests are important sources of the tiny particles of plant material that form the base of the food chain. "What you are doing is depleting the ocean of natural food for other fishes, sea birds and marine mammals," she said.
And, she said, much of the world's shrimp production comes from Latin American and Asian countries that do not all strictly regulate the industry.
The researchers pointed out that some types of fish farming were sustainable and could offer viable alternatives to wild-caught fish and act as a valuable food source.
"Good" farms produce carp, oysters and mussels, they said.
But there is a pressing need to consider the serious problems created in the growing $8 billion shrimp and salmon industries, the experts said.
"We are not damning all aquaculture," Lubchenco said. "Some types of fish farming will be an essential component of food for the future. We are saying these two are growing explosively, and these are ones where we need lots of improvements."
By Michael Kahn, Reuters News Service