Fish Farms Get Fried For Fouling

On land, strewn across the pebbly beaches of this quiet island, the sea cages look like a fleet of alien spacecraft. Their ring-shaped plastic floats, some 20 feet in diameter, await repair.

After their nets are attached, they'll join hundreds of other sea cages anchored off the foggy Fundy coast, whose waters teem with salmon being fattened for US dinner tables.

Such cages are at the center of a debate over the environmental impact of a rapidly expanding industry known as aquaculture.

New Brunswick salmon are part of this global industry - one that has doubled in size over the past decade and now accounts for a quarter of the world's food-fish supply, according to the UN Food and Agriculture Organization.

Proponents say aquaculture can reduce pressure on wild stocks of fish and provide new jobs, while helping to feed Earth's rapidly growing population.

Yet critics fear that intensive aquaculture operations are stressing seas, estuaries, and coastal ecologies often already damaged by overfishing, coastal development, and pollution.

"Aquaculture is going to grow because there simply will not be a supply of [wild] seafood products based on capture fisheries," says Leroy Creswell, an aquaculture research scientist in Fort Pierce, Fla., and a former president of the World Aquaculture Society.

"Many species are tapped out and in may cases have crashed or are in rapid decline. Aquaculture is needed to bridge the gap."

Asian shrimp farms are blamed for the poisoning and destruction of mangrove forests, key nursery habitats for many marine creatures. United States and Canadian salmon farms are blamed by many for contributing to declines in water quality, wild salmon populations, and deep-sea schooling fish that are caught and ground to feed penned salmon.

Salmon farms: Clean up your act

"It's an enormous industry and it's not just going to go away," says Frederick Whoriskey of the Atlantic Salmon Federation, a conservation group based in St. Andrews, New Brunswick. "We need to find solutions so that salmon farms clean up their act and function sustainably."

Freshwater aquaculture has been around for a long time. It is thought to have started in China about 5,000 years ago with the advent of carp farming. Then, as now, the closed carp ponds were fertilized with animal manure, producing the algae, plankton, and plants eaten by the fish. China still rules the roost today, accounting for nearly two-thirds of world production, much of it carp.

Today aquaculture is becoming as diverse as conventional agriculture. Seaweeds are harvested from Japan to California for industry, fertilizer, and food.

In some parts of the US, clam diggers plant sprats on their mud flats and collect them when they've grown, while oyster and scallop banks are often enhanced by planting hatchery-grown sprats. Cod, halibut, and sturgeon may soon join salmon growing in coastal sea cages.

The vast majority of the world aquaculture industry farms with little impact on the environment.

Freshwater carp, catfish, and tilapia are plant-eaters usually raised in special ponds where they help convert potentially harmful organic wastes into edible fish meat.

Shellfish like mussels, scallops, and oysters filter algae and plankton from seawater, so farmers don't add feed or medicine to the environment.

But the farming of other species - particularly shrimp and carnivorous fish like salmon - can be extremely destructive. Salmon are fed processed fish meal made from other fish.

Uneaten feed, fish wastes, and antibiotics fall from their crowded cages and are blamed for deterioration of water quality, bottom habitat, and disease outbreaks in wild fish populations.

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