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It has been several decades since there were enough fish in the sea to meet, on a sustainable basis, the growing worldwide demand for seafood--which accounts for 16% of global animal-protein intake, up from 14% in the early 1960s. About half the world's wild fisheries have been exhausted by overfishing. In the North Atlantic, one of the most depleted oceans, populations of popular fish (cod, flounder, haddock, hake and tuna) are just one-sixth of what they were a century ago. A European Union panel last week backed calls for a total ban on the fishing of cod in the North Atlantic and a moratorium on the fishing of haddock and whiting there.
Aquaculture was supposed to pick up the slack. It's already the world's fastest-growing food industry, with production increasing more than 10% a year. Farmed fish and shellfish supply 30% of all the seafood consumed worldwide today, up from 10% two decades ago.
But while the principles of aquaculture are generally accepted, experts fiercely debate which types of fish farming are safe to pursue. Says Andrew Fisk, 37, aquaculture coordinator for Maine's department of marine resources: "Aquaculturists used to be the good guys, and now they aren't, and there is a lot of anger on both sides."
On an eco-friendly scale, bivalves generally rate highest among the more than 220 species of fish and shellfish that are cultivated commercially. Mussels and oysters are filter-feeders that make the surrounding water cleaner, so small-scale farming of them is not usually harmful to the ecosystem. Farming of crayfish in China--the largest supplier to the U.S.--is a relatively low-maintenance, drug-free business carried out in rice paddies. Next come the vegetarian freshwater species that do not need large quantities of fish meal--carp, catfish and tilapia. At the bottom are salmon and shrimp, onetime luxury foods that, thanks to aquaculture, can be purchased around the world in any season at supermarket prices. Both species eat several pounds of fish meal to gain a pound of weight. And both create lots of waste.
To see fish farming at its worst, travel to Chile, where salmon farming has boomed in the past decade and generates $1 billion a year in export revenue. "A film of feed leftover made of fish oil, animal fat and transgenic soybean oil floats on the water around the salmon farms," says Ronald Pfeil, 67, a cattle farmer in Chile's remote Aysen region. "When the tide is low, the beaches stink."