The flesh of farmed salmon is a pale color, so farmers add the dyes canthaxanthin or astaxanthin or both to the feed salmon eat to give it a more orange color. If the fish is labeled "artificially colored" or "color added," it's a farmed salmon. If the restaurant menu calls it "Atlantic salmon" or doesn't mention that it's wild, it's most likely farmed. Wild Atlantic salmon is an endangered species and no longer fished commercially in North America.

Hatchery salmon are hatched, grown to a certain size and then released into the wild. If they survive, they go to sea and return to the place where they were released. Hatchery-originated salmon on the West Coast are fin-clipped so that fishermen can easily identify them from the depleted wild salmon that they must try to avoid catching.

Environmental groups complain that fish farmers use antibiotics, vaccines and other chemicals to counter the spread of disease within densely packed net cages. They advise consumers to reject farmed salmon, for flavor, health and environmental reasons.

But farmed salmon is cheaper and available year-round. Lauded for its heart-healthy omega-3 fatty acids, salmon is ranked by the National Fisheries Institute as the third most-consumed fish in America, behind canned tuna and shrimp.

Currently, farmed salmon supplies about two-thirds of the worldwide salmon demand. According to Salmon of the Americas, the aquaculture members' Web site at www.salmonoftheamericas.com, most American farmed salmon comes from the Pacific coast of Canada and Chile. The farmers maintain that the pens are safe for the fish and the environment and that the colorings used in the fish food are natural and approved by the FDA.

The Aquarius Fish Co. in Salt Lake City sells both farmed and wild salmon, but owner Dan Sheldon said he personally prefers eating the wild seafood.

"Farmed salmon is a good-quality product, although it has some problems with it," he said. "The wild stuff has more flavor, and it doesn't have the propensity for the diseases that farmed fish get. More of the restaurants will buy the farmed stuff because of the price, unless it's a high-end restaurant. They will have to charge more for the wild, because it costs more."

More retail customers are asking for wild salmon due to the negative publicity farmed salmon has received, said Sheldon.

"I think there's definitely a place for farmed fish, and the consumer wants the low price, but there's always a trade-off," he said. "It's good that all this information comes out, so the public can get the farms to change their techniques. Those practices were never really challenged before."