April 25 (UPI) -- A recent survey of seafood offerings from six restaurants in Washington, D.C., found a third of the offerings were mislabeled. However, the George Washington University researchers found no evidence of outright fraud.
Previous studies have shown rates of mislabeling and fraud vary between 26 to 87 percent at seafood and sushi restaurants, as well grocery stores, across the United States. Scientists at GW wanted to find out how District eateries stacked up in the honesty and accuracy department.
Of the 12 tested seafood samples, scientists found four were mislabeled. However, the four samples featured closely related species or acceptable substitutes for the listed fish.
"Diners that ordered tuna got tuna -- although maybe a slightly different type of tuna," Keith Crandall, director of GW's Computational Biology Institute, said in a news release. "We didn't see the kind of outright seafood fraud that has been reported in other cities."
Researchers collected their samples while dining at local establishments. Small samples were stored in a test tube and take back to the lab where researchers employed a DNA barcoding technique. A specific snippet of DNA coding is compared to a database of sequenced genomes to identify the species.
Scientists determined one order of "Chilean sea bass," two "tuna" dishes and one "rock shrimp" plate were mislabeled.
"For the most part, our study found that D.C. diners with a craving for seafood are getting what they paid for," Crandall said.
Crandall and his colleagues published the results of their study in the journal PeerJ.
Previous studies have found more egregious instances of seafood mislabeling, whereby cheaper species are passed off as more expensive, coveted types of fish. But it's not always the final seller who is doing the duping. Instances of fraud and mislabeling can occur at any point along the supply chain, from fisherman to distributor to fish monger to chef.
Scientists in Florida are currently working on fish identification technology that could make it easier for regulators to ensure honest, accuracy and quality at local fish markets.