America's fish: fair or foul?(Buyers Guide)

Fish is among the most perishable of foods, which is why Bud Knowles, director of quality control for the Stop & Shop Supermarket Co., which owns 270 stores in the Northeast, calls it "the most unforgiving item we sell."

Unlike beef and poultry, finfish typically arrive at the processing plant dead--sometimes dead for days. To make matters worse, they can decompose much faster than beef or poultry. That's due to the kind of enzymes and bacteria found on fish and the effects of oxygen, which can cause the "fishy smell" that is one sign of spoilage.

According to the most recent government figures, covering 1993 through 1997, seafood was to blame for 4.4 percent of all known cases of food-borne illness with an identifiable cause. Shellfish caused nearly three-quarters of the seafood-related cases--almost all of them gastrointestinal ailments in people who ate raw shellfish harvested from polluted waters. But there can be additional concerns with other types of seafood: contamination with natural toxins, mercury, and fecal matter, among them.

To assess the state of the nation's fish, we sent professional shoppers to Boston, Miami, Houston, San Francisco, Los Angeles, and Bettendorf, Iowa. Over the course of a week, each shopper visited four supermarkets (the kind of store at which most people buy fish) and one specialty shop. They bought fresh and previously frozen samples of five of the most popular types of seafood--salmon, tuna, catfish, shrimp, and cod--as well as red snapper and swordfish. To eliminate the possibility of bias, shoppers asked for a specific quantity of each type, then let the counter clerks choose the pieces.

Shoppers kept the seafood in its as bought condition by storing it in ice chests for the drive home. They then immediately transferred it to insulated boxes filled with frozen gel packs and shipped it overnight to a laboratory.

There, we tested for freshness, bacteria, and potentially harmful chemicals. At a second lab, we checked whether fish labeled as red snapper--a desirable species--was really red snapper or a different fish entirely. We determined whether the per-pound count of shrimp matched the count on the label. We also visited fishing boats, warehouses, processing plants, and stores to see where problems might arise. Finally, we examined the causes of the widespread depletion of fish, a serious issue since the early 1990s (see "Are We Running Out of Fish?" on page 30).

RESULTS, IN A SEASHELL