Salmon is part of the Pacific Northwest’s culture and diet. Wild-caught salmon are prized, and they cost more. It’s one reason Washington lawmakers passed legislation in 2013 making it unlawful to knowingly mislabel seafood. The law also requires sellers to provide information whether salmon being sold is wild-caught or farm-raised.

Dr. Tracie Delgado, biology professor at Seattle Pacific University, wanted to know whether the law has made any impacts.

Delgado and her students collected samples from 67 grocery stores and 52 sushi restaurants in Seattle. After genetically testing the samples, Delgado said overall, grocery stores were generally compliant.

“Grocery stores had about a 13.5% salmon mislabeling rate and sushi restaurants 23.1%,” Delgado said.

Delgado says the most common grocery store mislabeling was the salmon species. But sushi restaurants had a different issue. Turns out, more mislabeling happens in sushi restaurants. Delgado says one in three times, the salmon being served is farmed.

“I cant say exactly where the mislabeling is happening—it could be at the restaurant, it could be the distributors are not as reliable who are giving it to them,” Delgado said.

Her takeaway: if you really want to be sure you’re getting wild salmon, get it at the grocery store.

Delgado says in 2010 more than 1.6 million people in Washington ate salmon. Consumption is expected to nearly double (to 2.9 million) by 2030.

Delgado’s study is published in the journal PLOS ONE.