Fish Farms Get Fried For Fouling

And since farmed salmon and shrimp (normally a scavenger) are fed meals and oils made from small, edible schooling fish like mackerel, caplin, sardines, and anchovies, opponents point out that the farms are net consumers rather than producers of fish protein.

"By taking these fish out of the ocean to feed to farmed fish, we're undermining the integrity of the marine food web," says Rebecca Goldburg, staff scientist at the Environmental Defense Fund (EDF) in New York.

"On land we grow herbivores like chicken and cattle because it's an efficient way to make protein. It makes no more sense to grow carnivores in fish farms than it does to grow tigers on land."

According to a recent EDF report, US aquaculture operators have been authorized by the US Fish and Wildlife Service (USFWS) to kill a wide variety of birds that prey on farmed fish - particularly catfish, the most-farmed species here.

Nearly 52,000 birds were legally killed at US aquaculture facilities under legal permits in the four years between 1989 and 1993, according to USFWS data. Double-breasted cormorants represented half of the total, which included 9,443 great blue herons, 4,243 great egrets, and about 1,200 kingfishers.

Conservationists are also concerned about the shooting of seals and sea lions by salmon farmers trying to protect their teeming sea cages. Many Canadian farmers have installed underwater sound devices intended to drive away seals, but they may also be scaring humpback and minke whales feeding in these areas.

"Acoustic devices are keeping away the whales and possibly even the schools of herring that many other creatures rely on away from whole areas of the coast," says Inka Milewski of the Conservation Council of New Brunswick, which opposes further expansion of the province's large salmon industry.

Proper context needed

Aquaculture proponents admit that salmon farms have had negative impacts, particularly when overcrowding is allowed. But they say these problems must be understood in proper context.

"It's in the industry's own best interests to maintain the best possible environmental quality - the fish depend on that," says Jay Parsons, a researcher at the Memorial University of Newfoundland and former president of the Aquaculture Association of Canada. Proponents point out that the environmental impact of salmon or shrimp is far less than that of other industries that pollute the marine environment.

"Paper mills, oil spills, and municipal sewage all pollute the environment," Mr. Parsons says. "I'm not saying there aren't problems, but there are a lot of other things we should be concerned about that have a far greater impact than salmon aquaculture ever will."

Under pressure from regulators and sport fishermen, the industry is reportedly working on plant-based feed products and improved husbandry practices that reduce the risk of disease and pollution. Switching to closed-loop farms on land is an option that would reduce the impact of salmon farms by monitoring and treating waste water before it is released.

"Most people involved in aquaculture have a strong commitment to creating a responsible, sustainable industry," says aquacultural scientist Creswell. "But we can't do things with zero impact any more than you can drive a car to work or raise poultry without affecting the environment. Aquaculture is agriculture, it just happens to be done in the water. Terrestrial agriculture got thousands of years to perfect itself; in the sea we're having to do it in a few decades."

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