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Sushi Roulette: Is the Fish You Ordered the One You Got?

Image of sushi rolls on display.
Did you get the fish you ordered? In some sushi restaurants, it’s a flip of the coin. (Photograph: Wikimedia Commons/Tomek Strabski)

Have plans this summer to visit your favorite sushi restaurant? You might order spicy tuna roll. Or maybe salmon or halibut.

But is the fish you selected the one you got?

If you’re in Los Angeles or many other cities around the globe, it’s a flip of the coin.

Scientists at Loyola Marymount University, the University of California, Los Angeles (UCLA) and the University of California, Santa Barbara (UCSB) tested fish dinners at 26 L.A. sushi restaurants. The result: 47 percent of the meals were not as advertised.

The researchers used DNA barcoding to accurately identify the fish. “DNA barcoding is an increasingly popular tool for finding mislabeled products,” says Demian Willette of Loyola Marymount University, lead author of a paper reporting the findings in the journal Conservation Biology. “Our results should encourage consumers to demand strong truth-in-menu laws.”

Incorrect attribution of species names in seafood products is called species substitution. It often goes unnoticed “because it’s difficult to authenticate the identity of a fish once it’s in the supply chain,” says Willette. He and colleagues are working to change that.

Image of salmon sushi at unnamed restaurant.
In a recent study, salmon sushi was largely as listed on restaurant menus. (Photograph: Wikimedia Commons/Think Draw)

Truth in advertising?

Willette and other scientists tested 364 samples of 10 popular varieties of fish used for sushi.

The researchers visited L.A. sushi restaurants popular on the reviewing site Yelp and selected specific fish from the menus. When the orders arrived, the biologists asked the servers to confirm each fish’s name. The scientists then pulled out forceps and scissors, snipped off a piece of the fish, and placed it in a vial for DNA testing.

“Time and again, we found species labeled as different fish than what the DNA results showed,” says Samantha Cheng, a scientist at UCSB and co-author of the Conservation Biology paper.

Tuna sushi, pictured in an unnamed restaurant.
Sushi represented on menus as tuna is usually correctly labeled, researchers found. (Photograph: Wikimedia Commons/Peterjhpark)

Fish research in a restaurant

In 43 orders of halibut, the researchers were always served fish other than that species. But salmon was mislabeled only one in 10 times.

Spicy tuna roll-lovers can rejoice; sushi represented as tuna was usually exactly that. Some samples, however, turned out to be endangered Atlantic bluefin tuna or southern bluefin tuna.

The fraud undermines regulations limiting overfishing, interferes with consumers’ decisions and introduces health risks, the researchers say.

“Fish fraud could be accidental,” says Paul Barber, an ecologist and evolutionary biologist at UCLA and senior author of the Conservation Biology paper, “but I suspect that in some cases the mislabeling is intentional, though it’s hard to know where in the supply chain it begins.”

Mislabeling can harm people avoiding mercury-containing fish, such as pregnant women and young children. In other notable health cases, pufferfish sold as monkfish landed consumers in three U.S. states in hospitals. And almost one-third of halibut sushi examined in one study was olive flounder, a species that has caused parasitic infections in Japan.

Grocery store sushi selection.
Sushi display at a grocery store. How often are grocery selections mislabeled? Scientists hope to find out. (Photograph: Wikimedia Commons/Dllu)

Seafood fraud: On the rise?

Opportunities for seafood fraud are increasing, the researchers report. Almost 40 percent of the world’s captured seafood is internationally traded. The global fish trade is currently valued at more than $135 billion, so the stakes are high.

The Conservation Biology research took place in L.A., but other studies have uncovered similar problems, suggesting that the findings are widely applicable.

Indeed they are, according to a report by the marine conservation organization Oceana: Deceptive Dishes: Seafood Swaps Found Worldwide. One in five of more than 25,000 seafood samples was mislabeled, states the document. Seafood fraud was investigated in 55 countries, and found on nearly every continent.

In Brazil, 55 percent of “shark” samples were actually largetooth sawfish, considered critically endangered by the IUCN (International Union for Conservation of Nature). In Italy, 82 percent of 200 grouper, perch and swordfish selections were mislabeled. Almost half were species the IUCN lists as threatened.

“Consumers need to know whether their choices are adding pressure to already overharvested fisheries,” says Cheng.

On the U.S. East Coast, scientists at George Washington University in Washington, D.C., tested seafood meals at six D.C. restaurants. The researchers found that 33 percent of the selections were mislabeled. The swaps, they reported in the journal PeerJ, mostly involved closely related species.

One restaurant, for example, listed wild rock shrimp on the menu, but DNA barcoding showed that the item was in fact whiteleg shrimp. Whiteleg shrimp are usually products of aquaculture, and often are not as tasty as deep-water rock shrimp.

Red snapper, or tilapia? In sushi, tilapia is often substituted for snapper.
Are you eating red snapper – or tilapia? Tilapia is often substituted for red snapper, pictured here at a seafood market. (Photograph: Wikimedia Commons)

Finding the culprits

Despite all the switching, it appears that no one really knows where the blame belongs.

Logan Kock, chief sustainability officer of Santa Monica Seafood near L.A., has the job of educating the company’s suppliers and clients about correct seafood labeling. Santa Monica Seafood is a fresh and frozen seafood processor and distributor that delivers its products throughout the U.S. Southwest.

“We take a zero tolerance approach to seafood fraud, and only work with reputable purveyors who have passed a rigorous inspection process,” says Kock. “Periodic DNA testing also ensures that we’re always delivering exactly what customers ordered.”

He acknowledges that for the industry in general, however, “there are technical issues with transferring seafood across the supply chain accurately and credibly.”

Some businesses are responding by shortening that chain. Kyle Bowling, Chef de Cuisine at the Sushi Lounge at South Carolina’s Kiawah Island Golf Resort, says that the restaurant obtains all its seafood from in-state purveyors who limit sales to that region. “They use as much local product as possible,” says Bowling, “and bring in their fish whole then butcher them onsite, which eliminates the risk of misidentification.”

Display of various sushi choices.
Sushi roulette? It may depend on your choices. (Photograph: Wikimedia Commons)

Piscine bait-and-switch

Beyond the truth-in-sushi efforts of some restaurants and suppliers, organizations that offer sustainable seafood guides and certifications – such as the Monterey Bay Aquarium’s Seafood Watch Program, the Seafood Choices Alliance and the Marine Stewardship Council – are anti-fish fraud consumer resources.

The U.S. Food and Drug Administration’s Seafood List also registers acceptable market names for seafood sold in interstate commerce, including information on regulations and food safety hazards for each species.

“The success of these programs, however, relies on accurate labeling of seafood products throughout the supply chain,” says Willette. As fish move from harvesters to processors, adds Cheng, “reliable labels are supposed to stay with the fish all the way to the point of final sale.”

Next up: The California researchers hope to test incoming restaurant shipments to find out how fish such as halibut – and those who buy them – first get entangled in piscine bait-and-switch schemes.

“Business owners, consumers, scientists – all of us – have a shared goal of fisheries sustainability, and job and food security,” says Barber. “Otherwise, seafood industries, and the fisheries they depend upon, will ultimately disappear.”

Fisheries need to be sustainable, scientists say.
Fisheries sustainability, and job and food security, scientists say, should matter to all of us. (Photograph: Wikimedia Commons)

A version of this article appeared in Oceanography magazine.