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Sierra Magazine
Food for Thought: Old MacDonald Had a Fish

But salmon farming is nothing to sing about

For 25 years fish farming has been touted as "the next great leap" in food production. The World Bank and many others promised that rearing fish in ponds or coastal-water "netpens" would yield cheap, high-quality protein while relieving pressure on overfished wild populations. Aquaculture now accounts for a quarter of the world's fish supply, and farms for freshwater species such as catfish and tilapia do indeed seem to be sustainable.

The same cannot be said for two of aquaculture's most rapidly expanding sectors, shrimp (see "The Hidden Life of Shrimp," July/August 1998) and salmon. "Salmon farming probably causes more problems per pound of fish than any other form of aquaculture," says Jim Fulton, executive director of the David Suzuki Foundation, a Canadian nonprofit that supports environmental education and research.

Salmon farming began in Norway in the 1960s and spread to North America in the 1980s and Chile in the 1990s. The farms float open-topped netpens in coastal bays to raise fingerlings to maturity. Most operations, even in the Pacific, raise Atlantic salmon because they are adaptable, mature quickly, and spawn over a long time. Aquaculture produces over 710,000 tons of salmon a year, roughly half the world's supply.

To "grow" one pound of carnivorous salmon, however, takes almost three pounds of other fish, thus increasing fishing pressure. (In contrast, sustainably farmed freshwater species are raised on a largely vegetarian diet.) Open-water salmon pens also leak tons of feces and surplus food, polluting shoreline ecosystems; Norway's farms emit as much nitrogen as would the untreated waste of 4 million people.

Worse, the millions of salmon that escape from netpens each year may be disrupting wild salmon populations by introducing diseases and parasites, competing for habitat, and interbreeding. On the West Coast, fugitive Atlantic salmon have been caught in waters from the Pacific Northwest to the Bering Sea. Successful spawning by farm fugitives has been confirmed in at least two cases in Alaska, suggesting that populations are infiltrating the hundreds of streams that don't get closely studied. "Probably ninety-five percent of our streams aren't accessible by road, so they're generally only monitored by airplane surveys-and it's hard to spot a few Atlantic salmon from a plane," explains Glen

In 1990, Alaska banned not just salmon but virtually all aquaculture from state waters. "What we've seen since then in British Columbia has only confirmed our doubts," says Brian Paust, a professor of fisheries at the University of Alaska in Fairbanks. Calls for tougher regulations are also coming from Washington State, where 100,000 Atlantic salmon escaped from their netpens into Puget Sound last June.

Even on the East Coast, escaped Atlantic salmon vie directly with their wild cousins. Faster-maturing and more aggressive farm salmon may initially outcompete smaller, more cautious wild fish, but ultimately fail to survive. Breeding escapees may also alter the genetic makeup of wild fish, robbing offspring of the instincts needed to migrate and spawn.

And last year, federal biologists captured dozens of wild Maine salmon that carried a deadly virus detected only once before, 20 years ago in Scottish farm salmon. Some biologists worry that the virus may have contributed to the decline of Maine's wild Atlantics since then, despite improvements in their spawning habitat.

"Salmon farming as it's done now is simply unacceptable," says the Suzuki Foundation's Fulton. "It needs a complete overhaul." Fulton and many other environmentalists and wildlife managers call on the industry to abandon saltwater netpens in favor of more costly land-based closed ponds or tanks.

What can you do? Lobby your legislators (particularly in Canada, Maine, and Washington State) for industry reform, and buy only wild salmon. Other well-managed and abundant wild species include striped bass, Pacific halibut, squid, and crabs (except Alaskan kings). Among farmed varieties, try catfish, tilapia, or crawfish, or mollusks such as clams, oysters, and mussels. The ocean's bounty can be safety harvested, but it takes caring farmers and informed consumers.


David Dobbs, coauthor of The Northern Forest, writes on the environment from his home in Montpelier, Vermont.

(C) 2000 Sierra Club. Reproduction of this article is not permitted without permission. Contact sierra.magazine@sierraclub.org for more information.


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