When Kate Stoeckle, 18, and Louisa Strauss, 17, collected samples of fish from New York fish stores and restaurants on Upper Manhattan and tested them using the new genetic barcoding method, an astonishingly large portion of the samples turned out to be mislabelled and sold under the wrong name. A sushi restaurant claiming to offer white tuna was for instance serving their guests Mozambique tilapia instead, while another restaurant sold Spotted goatfish from the Caribbean Sea under the name Mediterranean red mullet.

Red Snappers

All in all, Stoeckle and Strauss collected 60 different samples of fish and had them tested at the University of Guelph in Canada. Four samples could not be identified by the genetic barcoding identification technique, but of the remaining 56 samples no less than 14 turned out to be mislabelled. This means that out of 56 samples, a whooping 25 percent were sold under false pretences.

All 14 cases of mislabelled fish consisted of comparatively cheap fish being sold as a more expensive species. It is therefore hard to see how the mislabelling could be the result of honest mistakes by fishermen or middlemen.

Not getting what you pay for as a consumer is however not the only problem with mislabelled fish; a false identity can also be used to sell endangered species to unsuspecting dinner guests. In the Stoeckle and Strauss study, two samples of alleged red snapper did for instance turn out to be endangered Acadian redfish (Sebastes fasciatus). The Acadian redfish has been listed as Endangered (EN) on the IUCN Red List of Threatened Species since 1996.

The study did not unveil the names of the restaurants and fish shops since it could not be determined if they were intentionally misleading their customers or if they had purchased the mislabelled fish in good faith.

Stoeckle and Strauss are both students at New York’s Trinity school.