Is Your Sushi What you Think it is?

Two teenage girls used DNA bar coding to determine that some sushi on New York dinner plates was mislabeled with cheaper fish being passed off as a more expensive species. Kate Stoeckle and Louisa Strauss took 60 samples of seafood and use a genetic fingerprinting technique to see whether the fish were labeled correctly.

The graduates of Manhattan's Trinity School in New York were inspired by Kate Stoeckle's father, Mark, a scientist and proponent of the use of DNA bar coding, a technique that greatly simplifies the process of identifying a species.

"Growing up, bar coding was dinner conversation, so I was familiar with it," Stoeckle said. "And then one night, while out to dinner, I asked, could we barcode sushi? Louisa and I love sushi, and we thought, why not apply the bar coding technology to see what food we're eating?"

After collecting samples from four restaurants and 10 grocery stores, spending about $300, the teens sent them to the University of Guelph in Ontario, Canada, where the Barcode of Life project began and where a graduate student had agreed to conduct the genetic analysis.

The girls' samples were compared with the global library of 30,562 bar codes representing nearly 5,500 fish species.

The results showed that 25 percent of the girls' samples were mislabeled: half of the restaurant samples and six out of 10 grocery store samples. In every case, less desirable or cheaper fish was substituted for its more expensive counterpart, Stoeckle said. She and her father would not divulge the names of vendors, citing a fear of lawsuits.

"It's not the fishermen, and it might not even be the restaurants," she said. "Most likely, the mislabeling is occurring somewhere at the distribution level."

For example, fish sold as white tuna turned out to be cheaper Mozambique tilapia, flying roe fish was replaced with smelt, and red snapper was mislabeled as Atlantic cod and Acadian redfish, an endangered species.