FYI.

This story is over 5 years old.

Tech

Your Tuna Might Not Really Be Tuna

A new study found mislabeling isn’t always a bad thing from a sustainability standpoint, but when it is, it’s really bad.

I've been mildly paranoid about mislabeled seafood every since I heard a This American Life episode episode about pig buttholes being passed off as calamari. While that turned out to be folklore, studies have shown seafood is often mislabeled, and new research found that this has a big impact on its sustainability.

Conscientious seafood lovers take overfishing into consideration when selecting their fish, opting for sustainable species that are plentiful. But with pervasive mislabeling, they don't always know what they're getting. A new study has found that, most of the time, the difference between the fish you think you're buying and the fish you actually get isn't a problem, but when it is, it's serious and may make you think twice about which options are really sustainable.

Advertisement

A group of PhD students at the University of Washington pulled data from 43 papers that used DNA testing to compare the seafood in a package to what its label read. They found that 23 percent of seafood samples were labelled incorrectly—though it's much more common in some seafood species, so their estimate of mislabeling across the whole seafood market is closer to 13 percent. Products labeled as snapper, for example, are often really rockfish or Nile catfish—a species the authors pointed out doesn't even look like a snapper.

"But once you filet it, it's pretty hard to tell the difference," said Margaret Siple, a PhD student in UW's School of Aquatic and Fishery Sciences and co-author of the paper.

A red snapper should be hard to mix up, but when it's cut into a filet it's harder to distinguish. Image: WikiMedia Commons

They then compared the labeled species with the actual fish in the package to see what kind of impact this issue has on sustainability: are more endangered fish hidden by being repackaged as sustainable alternatives? Most of the time, especially in the more popular types of seafood, they found this wasn't the case. The actual fish in the package was more often just as sustainable or even more sustainable than the fish on the label.

This was true of some of the most popular fish. Tuna was often mislabeled—about 20 percent of tuna is labelled incorrectly, according to the authors—but it was usually just swapped with another kind of tuna, or a similar species, and not a less sustainable fish. Salmon was rarely mislabelled, most likely because of its distinct pink color that makes it tricky to substitute, Siple said.

Advertisement

The problem is that in the less common instances where the fish in the package is actually more threatened than its label, it's usually a big gulf between the two. Hake, for example, is listed as a good, sustainable seafood option by the Marine Stewardship Council (as long as it's caught from inshore waters). But, according to Siple, hake is often substituted with Atlantic cod, which is listed as vulnerable by the International Union for the Conservation of Nature.

"Basically, if you get something that's less sustainable than what's on the label, it can be really bad," Siple said.

They also found that mislabeling can lead to a difference in price, but surprisingly, it often worked in the consumer's favor with higher-cost fish mislabelled as cheaper varieties. This indicates that mislabeling probably isn't happening intentionally, but is a result of lack of oversight throughout the supply chain, the authors wrote.

The findings shouldn't be taken as a green light to continue letting mislabeling run amok, said Christine Stawitz, a PhD student in UW's Quantitative Ecology and Resource Management program and co-author. Instead, this kind of research can help regulators identify problem zones—the fish most likely to be swapped for a less sustainable option—to target.

As for consumers, Stawitz said you can look for specific certifications such as the Marine Stewardship Council to make sure your seafood is truly as sustainable as the label suggests, and maybe take a little extra caution when it comes to trouble species such as hake, eel, and snapper.

"We're not saying mislabeling is a good thing," Stawitz told me. "We're saying there's a lot of heterogeneity, and there are definitely types of fish where the repercussions are bad and it's a huge issue and maybe those are the ones that should be targeted first."