When Dan Wasil plucks a white package of "Fresh Atlantic Salmon" from the grocery store cooler, he hardly glances at its label.

"I assume that it comes from the Atlantic," says Wasil, a fundraiser who has lived in Portland for over 30 years. While he says he’s careful to check labels to see if chicken has been produced without hormones, "as long as fish isn’t $800 a pound and it looks fresh, where it originates from doesn’t really matter."

It should.

Atlantic salmon don’t live in the wild and haven’t for decades. Rather, those boneless pink fillets were cut from fish raised in giant net pens in the Pacific Ocean along the Washington coast, and in Canada, Chile and Norway. Like feedlots, these pens are big business, producing 1.2 million tons of Atlantic salmon annually. In British Columbia alone, farmed fish have become the province’s largest agricultural export, bringing $603 million in to Canada.

Feedlot salmon grow fast, thanks to fish-feed pellets that look a lot like brown Tart ‘n’ Tinys. The pellets are an amalgam of fish oils, grain and fishmeal from herring, mackerel and sardines. In the process of making pellet food, producers also inadvertently intensify the concentration of dioxins and Polychlorinated biphenyls that get fed to the fish.

PCBs and dioxins are known to cause cancer, high blood pressure and strokes, and farmed salmon have more than 10 times the amount of PCBs than their wild counterparts. At these elevated levels, women and children are advised not to eat more than one serving of farmed salmon a week, according to the UN’s World Health Organization.

But that’s not all. The food pellets contain antibiotics to stave off diseases easily spread in the close quarters of farm pens. While the industry has decreased the use of antibiotics by over 90 percent in the past decade, an internal audit by the Canadian Food Inspection Agency that a small percentage of farmed salmon tested positive for antibiotics. The agency chose not to recall the meat because of the rapid nature of processing and exportation.

There’s more. Atlantic salmon don’t look like wild salmon, so some aquaculture companies fold in a color additive called canthaxanthin to the food pellets. They lend the gray fish a sunset color that the J. Crew catalog likes to call "salmon."

They do this because farm salmon don’t eat the krill that makes their wild cousins a riotous pink. But anthaxanthin may brighten the meat at the cost of damaging consumers’ eyesight. After studies showed increased vision problems among people who eat farmed fish, the European Union slashed the use of the pigment by a factor of three. Here in the United States, there are no restraints on using the colorant.

Perhaps most disturbing is that consumers don’t know much about Atlantic salmon, and few grocery stores bother to set us straight. That may be about to change. Eight consumers filed a class action suit in Seattle in late April against three of the nation’s largest grocery chains for not making public how their Atlantic salmon was raised and what colorants were added to it.

Now, after a spate of bad press, two of the companies -- Kroger Co. and Albertsons Inc., though not Safeway Inc.-- have pledged to label the fish as "artificially colored." While people who monitor food issues call this a "great victory," we consumers better keep asking our retailers questions.

Several organizations are working to help us make better seafood choices. The Marine Stewardship Council, an international nonprofit with U.S. headquarters in Seattle, Wash., has created a certification process that designates seafood as healthy for both the environment and people.

Along the same lines, California’s Monterey Bay Aquarium offers a free, wallet-sized guide that tells consumers which fisheries produce salmon and other fish in a sustainable manner. Farmed fish don’t make the list.

Those of us who congratulated ourselves for switching from red meat to Atlantic salmon need to get smarter, for it seems what we’ve done is substitute one feedlot for another. It reminds me of the time Americans were told to switch from butter to margerine, only to be advised later that butter really was better for our health.

Fortunately, some fish is still a healthy choice for dinner. That choice is wild and hatchery-raised salmon, and it’s available at most grocery stores. It will certainly be there if consumers who have informed themselves ask for it. While wild salmon may cost more per pound, you’ll know you’re getting the real thing.

Rebecca Clarren is a contributor to Writers on the Range, a service of High Country News (hcn.org). She lives in Portland, Oregon, and has written extensively about farmed fish along the Pacific Coast. This is the first of two columns on the subject.