Buyer beware: your salmon might be lying to you. In a study released today, researchers found that these products are routinely mislabeled as wild salmon when they are actually farmed salmon, which can be particularly costly for restaurant customers of sushi.

Mislabeling of salmon and seafood has been a known problem for some time, so much so that Washington State, where the salmon industry is particularly importantpassed a law in 2013 intended to reduce this and other types of fish-related fraud. Lead researcher Tracie Delgado, a biology professor at Seattle Pacific University, had read previous studies on the topic and was familiar with the 2013 law, so she decided to have students in her genetics lab class do their own investigating. themselves to find out if things had improved since then. .

“We had no idea of ​​the results when we started this project and we were very surprised by the results,” Delgado told Gizmodo. “Despite Washington state legislation that makes salmon mislabeling illegal, salmon mislabeling fraud remains a problem in Seattle.”

Delgado and his students collected and analyzed DNA from salmon samples from 67 grocery stores and 52 sushi restaurants in the Seattle area between fall 2022 and fall 2023. In total, 18% of these samples were mislabeled. The team’s conclusions were published Wednesday in the newspaper PLOS-One.

Although labeling errors were relatively common in grocery stores and restaurants, they were a more serious problem in the latter. For example, about a third of samples from restaurants were mislabeled wild salmon rather than farmed salmon, compared to zero mislabeled samples from grocery stores. And sometimes sushi samples marketed as a specific species of wild salmon were instead another wild species, although this also happened in grocery stores (the combined ratio of wild to farmed salmon and wild to wild salmon was 38% in restaurants and 11% in restaurants). stores).

On the bright side, researchers found no cases of farmed salmon being mislabeled as wild in grocery stores. This suggests that Washington’s seafood identification laws have helped mitigate fraud at least a little. But the overall rate of salmon mislabeling found in this study is consistent with some past estimates of Washington’s mislabeled rate before the 2013 law, while later studies found even higher prices in other states. And the costs of mislabeling salmon at sushi restaurants are almost certainly passed on to customers, since some people will end up paying more for “wild” salmon that should actually be cheaper farmed salmon (this said, this potential effect turned out to be insignificant). in grocery stores).

According to Delgado, improper labeling of salmon is also likely to have a negative impact on the environment.

“Dishonest reporting of catch data and mislabeling of seafood complicate fisheries conservation efforts because they prevent accurate tracking of supply chains and complicate efforts to effectively manage fisheries,” a- she declared. “As a result, fisheries managers may incorrectly conclude that wild salmon stocks that are actually depleted persist at sustainably exploitable densities. »

Researchers say more needs to be done to stop fraud in salmon and other types of seafood, including encouraging restaurants to periodically verify that the fish they buy is the real deal. There is a existing inspection program set up by the National Oceanic and Atmospheric Administration for fishing boats, processing plants and retailers to test their fish, Delgado notes, although participation is voluntary. And while sushi customers may not be able to physically detect mislabeled fish, they too can take steps to at least reduce their chances of being defrauded.

“Customers can ask sushi restaurants if they have a quality control process that confirms salmon identification and if they have reliable suppliers that sushi restaurants source from,” Delgado said . “Customers can also ask sushi restaurants if they buy the salmon whole and then fillet it at the restaurant,” or if the original salmon is already processed. “If the salmon is filleted fresh at the restaurant, then a good sushi chef will know the difference between wild salmon and farmed salmon by looking at it,” she explained.

Ultimately, however, it will likely take the adoption and enforcement of stricter seafood fraud laws to effectively curb the practice.