While this puts restaurants at risk—unwittingly selling a fraudulent product is never good publicity—the harms of seafood fraud fall disproportionately on consumers. Besides spending more for a lower-value product, they may be paying for the health risks that come with unchecked fish. Federal officials at the National Oceanic and Atmospheric Administration (NOAA) have discovered FDA-banned antimicrobial agents and high levels of mercury in imported grouper. The Oceana report also found that 84 percent of white tuna samples were actually escolar—a fish that causes digestive problems—in disguise.

Short of building a home laboratory, there’s not much consumers can do to make sure that they’re buying the fish they’re paying for. They can try to stay sensitive to prices that are too good to be true, or they can buy seafood from a member of the Better Seafood Bureau, a trade organization that documents and reports fraud along the seafood supply chain.

They might also seek out the 10 percent of fish that isn’t imported—as it turns out, our domestic fisheries tend to follow the rules for seafood labeling. “We have some of the better managed fish and show evidence that some species are being rebuilt after getting overfished,” says Warner.

In his 18 years as a forensic scientist at NOAA, Trey Knotts has seen more than 2,000 catfish filets in disguise. Recently he has been seeing more mislabeled species coming in at up to half a million pounds per shipment. “There are individual companies importing millions of pounds of mislabeled fish,” he says.

Meanwhile, less than 1 percent of imported seafood is inspected for mislabeling. This is not for lack of trying. Knotts says NOAA has fewer than 100 agents who do inspections. “If you consider the coastline of the U.S., it’s a massive amount of territory to be covered by 90 agents,” he says. (Thanks to diminished federal funding, this number is growing smaller still.)

So what’s being done about our leaky seafood system? Warner’s study exposed the magnitude of the problem, and now the Obama administration is taking steps to combat fraud. One of the most ambitious proposals this year will be for federal agencies, such as NOAA and the FDA, to work together more closely on seafood-fraud investigations. And with a new set of tools on the way—including Grouperchek, a tested device soon to be available for commercial use later this year—the government and the industry appear closer than ever to fighting seafood mislabeling.

Researchers unanimously blame foreign fisheries for seafood fraud. Ninety percent of our fish is imported from countries with loose aquaculture laws, such as Thailand, Indonesia, Canada, China, Ecuador, and Vietnam. Some seafood from these countries may come mislabeled from unregulated fish farms. The most notorious offenders are Thailand and Vietnam, a country with polluted fish farms along the Mekong River teeming with Asian catfish ripe for export.