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Los Angeles is, in all likelihood, the original home of sushi in the United States. The first mention of the raw fish dish in America dates back to 1904 in the Los Angeles Herald. And you might think that with over a century of tradition and history on its side LA wouldn't be screwing up its sushi. You’d be wrong, at least according to four years of research from UCLA and Loyola Marymount University. A study published yesterday in the journal Conservation Biology found that almost half of the fish from more than two dozen different sushi restaurants was mislabeled.

Paul Barber, a UCLA professor of ecology and evolutionary biology, and his team went to 26 restaurants with high customer ratings on Yelp. In an email Barber told me they hit a broad cross section of LA restaurants that “ran the gamut from some very high end establishments (both large and small) as well as low and middle of the road places.” Researchers ordered nine different types of fish and tested the DNA from each of them. The findings are, at best, disappointing for those of us who don’t just order California and spicy tuna rolls.

47 percent of the sushi turned out not be what the restaurant claimed. Some species, though, fared much worse than others. Exactly zero samples of halibut and red snapper ended up being halibut or red snapper. In the case of halibut, the actual fish was found to be flounder and in the case of snapper the sushi was usually made from red seabream or tilapia. The halibut swap is particularly problematic because some of the fish served was, in reality, raw olive flounder, a species that caused an outbreak of gastroenteritis several years ago.

According to the researchers, if you want to actually get what you ordered, the safest sushi is salmon or mackerel. Salmon, which on occasion was substituted with trout, turned out to be mislabeled just 13 percent of the time while mackerel was mislabeled only 8 percent of the time. Before you start hurling wasabi at your local sushi chef for lying to you, I’ll note that while Barber and his team carefully documented all the misinformation, they did not, make any firm conclusions about whether the problem stemmed from individual restaurants deceiving customers or suppliers deceiving restaurants.

There is though, amongst all this fish fraud, one somewhat positive finding: By serving customers things like tilapia rather than red snapper, restaurants are forcing customers into more environmentally-friendly behavior. As Barber pointed out, if someone is looking to make more sustainable fish choices, “tilapia should be at the top of their list and red snapper should be at the bottom.” He thinks this could open the door for a shift in our sushi consumption, at least with the right sales pitch. “What [the research] indicates is that done right, fish like tilapia can be made into sushi that customers are happy with. There is so much tradition in this industry that it might be difficult to have a wholesale switch away from traditionally served fishes…but I suspect an innovative chef could make some real inroads into the market here with such an approach.”

So Angelenos, while you’d certainly be justified in some outrage over mislabeled fish, the next time you go out to get sushi try ordering tilapia and see what happens. You might confuse the waiter, but at least you’ll get what you asked for and you’ll be able to feel good about it to boot.