14 Things You Should Know About Sustainable Sushi

Since the 1960s, our global seafood consumption has increased by 228%. Growing concerns over the future of our oceans are pushing chefs and consumers to reconsider their relationships with seafood. Though sushi is a rice-based dish, it's synonymous with fish, and the number of sushi restaurants in the United States has increased an average of 4% each year since 2018. Many of these restaurants rely on the same few varieties of seafood to satisfy their clientele and sustain their businesses, but some chefs are pushing back on the norm.

At Sozai, a sustainable sushi restaurant in Metro Detroit, Chef and Owner Hajime Sato only works with a select few varieties of seafood. This past year, Sato was one of five chefs nominated for the James Beard Award for "Outstanding Chef" for his work in sustainable sushi, though he thinks this distinction is silly. ("There should be no 'sustainable sushi chef,'" says Sato. "It should all be sustainable.") We sat down with Sato to discuss what he thinks diners should know about the sustainable sushi trend and whether or not he believes it's possible to operate more restaurants like his. (Spoiler alert: Sato knows it's not only possible but necessary, though he's candid about the hard road ahead for aspiring proprietors.)

According to Sato, his sustainable sushi restaurant contemporaries are in decline, largely because their chefs have thrown in the towel. "Fifteen years ago, there were more sustainable sushi bars. It's less now, much less. Because it's really hard," says Sato. According to Casson Trenor, the author of the book "Sustainable Sushi: A Guide to Saving the Oceans One Bite at a Time," as reported in the The Seattle Times, the movement has died down since sushi restaurants began operating in this way in the late 2000s. A lack of consensus around a unifying philosophy is partially to blame for the movement's diffusion: Some thought sustainable meant "vegan," like NYC's Beyond Sushi, while others relied on seafood supplier certifications to bolster their claims of sustainability. Yet all chefs endure continuous, painstaking education and re-education. "There were some legit people. It was so small. They gave up. It's too hard," says Sato.

Sato was personally disappointed with the film Seaspiracy, which claims that sustainable fishing doesn't exist despite organizations actively supporting such ends. Though the film may have highlighted the dire circumstances of the ocean's fish populations, it also breeds confusion and mistrust in anyone or anything working to create and promote sustainable fishing practices. This runs the risk of disengaging consumers from the movement and disenchanting consumers from believing more sustainable seafood dining options — like Sato's — exist.

From chef to supplier, no agent in the seafood supply chain is more important in determining which kinds of seafood, sustainable or otherwise, end up on the diner's geta than the diners themselves. You've probably grown to expect the same few varieties of fish appearing on a sushi menu, like hamachi (yellowtail), ahi (bluefin tuna), and unagi (eel), without giving their sourcing much thought. Consumer demand for the same few fish species puts pressure on chefs and suppliers to deliver at any cost. "Everybody wants to consume the same fish — that's the problem. [Consumers] expect me to have yellowtail and bluefin tuna and the six or seven fish that they know," says Sato.

Of course, suppliers can limit what they supply, and some, like those who are a part of Sea Pact, have agreed to do just that. Ultimately, though, distributors and restaurants alike need to meet a certain public demand, which requires servicing an appetite that hasn't caught up with the reality that sushi can no longer be excluded from the sustainability zeitgeist.

You might think that the easiest way for chefs to ensure the sustainability of the seafood is simply by sourcing what's local. (Sato, who relocated from Seattle, now knows his way around the Great Lakes.) However, having a full picture of sustainability requires thinking both locally and globally. Fisheries in the United States are well-managed compared to many across the globe. However, current estimates put the United States at around 60% of exported fish to meet our total seafood consumption. Some estimates predict that it's even higher — around 90%. (The difference in estimates is due to several factors, namely unreported catches, and fish that are re-imported after overseas processing.)

While keeping things local could cut back on carbon emissions, globalization is critical to our economy — and it would be difficult to be successful in the Midwest as a sushi restaurant by offering local varieties of fish only. "How local can I go? Of course, I think about it ... you have to think big and small at the same time," says Sato. Though sustainable sushi chefs will utilize local fish — especially lake and river fish — these are generally not the only species on their menu, and most others require thinking about sustainability globally. "You have to think about how fish are caught between Holland and England because that fish might go around [the world] and come back over here."

If you're trying to determine the ethics of a sushi restaurant, simply take a peek at their sushi list. Though some fish with poor reputations can still be harvested sustainably, other species are notoriously overfished. Sato disavows the much-lauded bluefin tuna, going so far as not putting it on his menu. So, is tuna a sustainable seafood or not? That depends. Many of the most popular tuna species are at risk of becoming endangered, and those that are not threatened are fished using methods that result in excessive amounts of by-catch.

Then other species of fish are just plain bad for your health. Take escolar, a fish that's on sushi menus under the pseudonym "Super White Tuna." Escolar contains a toxic fat that can cause severe gastric distress if ingested in even moderate amounts. "It's banned in Japan and most European countries because it contains a waxy substance called [gempylotoxin] and we cannot digest it. It's legal [in the United States] because fisheries push it and it's cheap," says Sato. While it may be legal in the U.S., the U.S. Food and Drug Administration still warns proprietors against putting the fish on their menus, though not all comply. In 2009, a study conducted by Columbia University and the American Museum of Natural History analyzed nine dishes billing themselves as "white tuna" at sushi restaurants across Denver and New York City and found that five of these were escolar.

"Everybody thinks that fresh fish is better, but freezing technology is really good," says Sato. Today, much of the seafood sold in sushi restaurants has been flash-frozen, which means the fish's temperature is immediately reduced to -40 to -60 C after the fish has been caught. This rapid freezing technology ensures the integrity of the protein post-thaw, avoiding the mushiness generally associated with common frozen products such as vegetables. Not only are flash-frozen fish delectable, but they're economical and sustainable, too. Fresh fish requires the fish to be shipped as quickly as possible — by plane — while frozen fish can take a more leisurely and less carbon-heavy journey by boat, train, or truck to get to your plate.

Consumer research echoes Sato's sentiments — that the term "freshness" is the highest-ranking consideration for people buying fish, despite much of the fish sold in grocery having been previously frozen and labeled as such. "I always say: What if the fisherman caught this fish in the boat [and didn't freeze it]? It might take two weeks to get here, and it's not frozen. Or there is a processing plant that's right by the fisherman, and they freeze it at -60˚C right by the fishery. Which one do you think is fresher?" Doing away with frozen fish's bad reputation can also expand the possibility of offering sustainable sushi menus across seasons. "There's a lot of seasonality in the fish. So there's kind of a balance on using frozen fish that's more sustainable and caught in a certain way so that it can kind of give you a more steady supply," says Sato.

We've seen it happen with beef. Now seafood is going "plant-based" too, with products made from legumes and vegetables calling themselves "fish". Ocean Hugger Foods has keyed in on two of the most at-risk sushi fish — Atlantic bluefin tuna and eel, creating plant-based "texture-driven" alternatives that sub in for the real thing. "Ahimi" is a tomato-based alternative to raw ahi tuna made from tomatoes, gluten-free soy sauce, sugar, and sesame oil, while "Unami" is a similarly soy-flavored but made from eggplant instead of tomato. Sato is dubious of plant-based alternatives like these, questioning their role in overthrowing an unsustainable market if they potentially replace it for another: "Plant-based is heavily processed ... and all of the nutrition is not there. You might as well eat Doritos and call it a day." The unagi this plant-based brand emulates closely mimics nasu nigiri: eggplant sushi that's been a part of the dish's history much longer than Ocean Hugger has. 

There are traditional types of sushi rolls that don't contain any raw fish: Kappa (cucumber), shinko (pickled radish), and kampyo (made with dried gourd) nigiri are inherently vegetarian. "I love vegetable sushi. If you go back to my grandma's cooking ... it was all [made with] vegetables because we couldn't afford to buy fish." Sato's philosophy on eating sustainability remains simple: Reduce protein consumption and eat more vegetables. "Don't do fake tuna, fake this, fake that. ... What's the point?"

Another sustainable source of protein for sushi is invasive species. These non-native fish, like lionfish, zebra mussels, and periwinkles, cause environmental and economic harm to their habitats — a boon for chefs looking to create dishes with more than one bottom line. However, sourcing these species can be difficult, as supply chains are not set up for them. "To source them, you need [many] restaurants that want to buy them so that they're economically viable for the fisherman to catch. ... Again, it fails at a supply chain [level]," says Sato. Instead, chefs have to forage for these species themselves. "People talk about it all the time – we should be eating [invasive species]. Okay, great. But I don't have time to go the Great Lakes to catch all of the goldfish and come back."

On Sato's wishlist are the blue catfish and jumbo feral goldfish that invade the Great Lakes and the aforementioned lionfish, which is difficult to catch because it lives in reefs. When asked if there are trade-offs to flavor, Sato says, yes, these species can be more difficult to work with, but ultimately, he won't know until he gives them a taste: "Can I at least get them so that I can say that they're horrible?"