Almost half of sushi served at 26 restaurants over four years in Los Angeles was found to be mislabelled, according to a study.
Researchers from UCLA and Loyola Marymount University checked the DNA of fish ordered at 26 sushi restaurants between 2012 and 2015 and found 47% was not what it was claimed to be.
Out of 43 orders of halibut and 32 orders of red snapper, all the servings were a different kind of fish. However, tuna was almost always tuna, while salmon was mislabelled on around one in 10 occasions.
Sampling of high-end grocery stores found similar mislabelling rates, suggesting any switching was taking place in the supply chain rather than at point of sale.
Paul Barber, UCLA professor of ecology and evolutionary biology and senior author of the study, said: “Half of what we’re buying isn’t what we think it is.
“Fish fraud could be accidental, but I suspect that in some cases the mislabelling is very much intentional, though it’s hard to know where in the supply chain it begins.”
Over four years researchers tested 364 samples of 10 popular varieties of fish used for sushi. The study, which appeared in the journal Conservation Biology, noted the global fish trade was worth $135bn.
The study found that only bluefin tuna was always as advertised, and while only one of 48 samples of tuna was not tuna, sometimes different types of tuna were swapped. Two samples turned out to be Atlantic bluefin tuna, classified as endangered, and southern bluefin tuna, which is critically endangered.
All halibut and red snapper orders failed the DNA test and in nine out of 10 cases diners ordering halibut were given flounder.
Meanwhile, the US federal government introduced new regulations on 9 January this year as part of efforts to trace catches back to harvest to protect endangered species and cut fraud.
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