It’s hard to find a largetooth sawfish in some tropical waters in the Pacific and Atlantic. This long-snouted ray is critically endangered, its numbers dropping fast.

But that hasn’t stopped fishermen from catching them illegally in Brazil, and it hasn’t stopped vendors from mislabeling them as shark, which is legal to sell. In fact, it’s not uncommon for threatened and endangered fish to end up at markets all over the world labeled as another species, according to a new report from the marine conservation group Oceana.

That means that when it comes to fish, going green may be no easy feat. You might think you’re buying a sustainable species for dinner when in reality that fish may be swimming toward extinction.

“That endangered seafood item is one fewer individual from that population that is struggling,” says Kimberly Warner, a senior scientist at Oceana one of the authors of the report, released on September 7.

Beth Lowell, senior campaign director at Oceana, says fishermen often mislabel species either caught as bycatch or purposely caught in violation of the law. “They’re going to label it whatever they want to label it to make sure they can sell it in the open market,” she says. “There are few controls right now in the seafood supply chain so it’s really easy to pull a bait and switch.”

Swapping Seafood

Oceana, which has long looked into seafood mislabeling, reviewed more than 200 studies, media reports, and documents from governments and NGOs examining seafood fraud in 55 countries for its paper. The results don’t bode well for fish lovers—or for fish themselves.

The authors found fraud at every level of the seafood supply chain, from distribution to retail. One in five of the more than 25,000 samples tested was found to be mislabeled, on average, and researchers discovered fraud in every area studied except one. Studies released in the past two years focusing on the United States, for instance, showed that on average 28 percent of fish are labeled as another fish, according to the Oceana report.

In the U.S. fish labeled snapper, grouper, and salmon were least likely to actually be those types of fish. In Europe, hake and sole were mislabeled the most. In many cases, fish labeled as one type of species were actually cheaper, less desirable fish.

And sometimes vulnerable ones. Sixteen percent of the fish mislabeled as other species were found to have some level of conservation risk, the report notes, and the population numbers for more than half of the fish identified as substitutes are unknown.

View Images An endangered sei whale surfaces off the coast of Portugal. A California sushi restaurant passed off sei whale meat as tuna, marking one of many instances of threatened species being substituted for other types of fish. Photograph by Alamy

Among the findings: Critically endangered speckled hind gets passed off as grouper in the U.S.; the regulated Patagonian toothfish, also known as Chilean sea bass, is labeled as sablefish in China; and 20 percent of assessed snapper species in the U.S. are actually species that face a high risk of extinction in the wild.

In one instance, a sushi restaurant in California labeled the meat from the endangered sei whale as fatty tuna to hide its identity. (Also see “More Than One-Third of U.S. Shrimp May Be Mislabeled, Study Says".)

Aside from conservation concerns, the report notes that this rampant fraud has serious health implications. According to the paper, more than half the samples identified as a substitute species carried a health risk, including parasites, chemicals, and toxins such as ciguatera, which can cause neurological problems.

But not everyone is convinced that the group’s conclusions bear weight. According to Gavin Gibbons, a spokesperson for the National Fisheries Institute—the leading trade group for the U.S. seafood industry—the report is misleading.

“The study suggests that 20 percent of all seafood globally is mislabeled, and that isn’t accurate,” he says. “The studies they looked at focused on commonly mislabeled species. The report distorts the findings by design.”

Mislabeling in the Spotlight

After earlier reports revealed instances of widespread seafood fraud in the U.S., in 2014 President Barack Obama commissioned a task force to combat illegal fishing and seafood fraud. The task force proposed a rule that would require better tracking of 13 types of seafood particularly at risk for fraud, monitoring that seafood only as far as the U.S. border.

Oceana wants the report's results to push the U.S. to extend the requirements to all seafood and expand the regulations so that they track species after they’ve crossed into the country. The group holds up as an example laws enacted by the European Union that may have made a difference. There, fraud dropped from an average of 18 percent in 2012 to 8 percent last year, Oceana found.

Meanwhile the National Fisheries Institute says that more regulations are not what’s needed. “If they were lobbying for more enforcement, we would be in lockstep,” Gibbons says. “But they’re saying drivers are running a stop sign—and it doesn’t make sense to put up another stop sign. They’re asking for more bureaucracy.”

The final rule should be issued by the end of the year, Warner says. In the meantime, a number of innovators have taken matters into their own hands by developing software that tracks fish, shrimp, and other types of seafood.