There's something fishy about seafood, an international ocean advocacy group contends in Bait and Switch, a seafood fraud report released Wednesday. According to Oceana, in Washington, D.C., seafood is often mislabeled in restaurants and at stores. Packaging and processing may also underestimate the amount of breading and ice in frozen fish products.

Citing DNA tests of 1,000 fish filet samples from dozens of U.S. cities over the past four years, the report said that only 50% of the fish tested were the species listed on the label. Fish labeled as red snapper, wild salmon and Atlantic cod are actually other fish 25% to 70% of the time, the report said, with rockfish and tilapia often substituted for snapper, farmed salmon for wild, and pollock for Atlantic cod.

"Species substitution is a way illegal fish can be laundered into the seafood market," said Michael Hirshfield, Oceana's chief scientist. "Species substitution not only undermines legal fishermen and legal fishing by allowing illegal fishing to flourish, it also undermines consumer-driven efforts to do the right thing and ask for species that are responsibly managed."

Eighty-four percent of seafood eaten in the U.S. is imported, but only 2% is inspected, the report said. Hirshfield said the best way to ensure fish is legal and accurately labeled is with a national tracking database using bar codes, similar to the way Amazon tracks its packages.

"There should be no problem in tracking fish back to a particular vessel that caught the fish at a particular time in a particular place in a particular way," Hirshfield said.

A spokesman for the U.S. Food and Drug Administration said the agency is unsure how often fish substitution occurs. "When we find it, we act on it," said the FDA's Douglas Karas, citing cases in 2010 and 2009 in which companies had been caught mislabeling perch as red snapper and northern rock sole as grouper fish.

Karas said the FDA has been working with academic and regulatory researchers to validate a DNA-based method to identify seafood, but it does not currently have a seafood tracking database. The agency has been developing a library that can be used to identify seafood species with DNA barcoding and is currently using DNA sequencing equipment at some field labs to combat "misbranding that results in both seafood safety and economic adulteration violations," Karas said.

"Our plans are to conduct an international collaborative trial of the [DNA barcoding] method in hopes of receiving international accreditation," he said. The FDA is working with U.S. Customs and Border Protection labs to screen imported fish and, on almost 50% of seafood imports, is using a risk-based computer system that can better target misbranded fish, he added. The FDA started using the computer system last year.

The FDA urges consumers to beware of unusually low prices for fish they know generally cost more.

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-- Susan Carpenter

Photo: Seafood and fish at Pike Place Fish Market in Seattle. Credit: Mark Ralston / AFP / Getty Images