The science of sustainable seafood, explained

Sustainable sushi: evaluating the 9 most popular species in the U.S.

“Sushi As We Know It Will Not Survive. Can the restaurant industry reinvent it?” asks an April 2022 headline in Bon Appetit Magazine. It follows Vice’s “Sushi as we know it will be wiped out by 2050” and the Chicago Tribune’s “The end of sushi as we know it” in a long line of sushi-as-we-know-it alarmism. Perhaps more than any other seafood category, sushi is associated with severe overfishing and is something we must avoid or “reinvent” to sustain ocean health.

This message is not totally incorrect.

Though stocks of cornerstone sushi species like bigeye and yellowfin tuna are generally healthy, they often come from fisheries that constantly challenge fishery management systems and traceability. Others, like hamachi and eel, have few sustainable sources and are almost exclusively imported with little information.

Finding sustainable options for all the top sushi species commonly seen in the US is not always easy, but sustainable sushi is widely available. This fact may not be as compelling as a call for industry-wide reinvention, but for International Sushi Day, we wanted to more accurately summarize the sustainability landscape of your favorite sushi items to supplement our Buying Guide.

To start, we collected seafood ratings and certifications and totaled “unsustainable” and “sustainable” sources for popular sushi species categories in the US (see figure 1 below). “Unsustainable” was defined as any source rated “Avoid” by Monterey Bay Aquarium’s Seafood Watch program. “Sustainable” was defined as any sources rated “Best Choice” or “Good Alternative” by Seafood Watch and any MSC certified, ASC certified, or BAP certified 2, 3, or 4-star sources. We also included Fishery Improvement Projects (FIPs) that qualified as “comprehensive” according to Fishery Progress. These definitions are consistent with most grocery store sourcing policies in North America, however, we did not include labor and human rights considerations in these definitions.

Figure showing potential sustainable sushi sources. The number of source ratings for popular sushi species categories in the United States. “Avoid” applies to red-rated fisheries by Seafood Watch. Total “Sustainable” combines: Seafood Watch green and yellow ratings; MSC certifications; ASC certifications; BAP 2-star or higher certifications; and comprehensive FIPs. BAP farmed salmon sources were not included in accordance with Seafood Watch benchmarking.
Figure 1. The number of source ratings for popular sushi species categories in the United States. “Avoid” applies to red-rated fisheries by Seafood Watch. Total “Sustainable” combines: Seafood Watch green and yellow ratings; MSC certifications; ASC certifications; BAP 2-star or higher certifications; and comprehensive FIPs. BAP farmed salmon sources were not included in accordance with Seafood Watch benchmarking.

Figure 1 shows that there are sustainable and unsustainable sources for each of the top sushi species categories, but it doesn’t properly represent the proportion of sustainable sushi products because it does not measure volume, only individual sources. To better contextualize these results, we dive into additional analysis for each species category below:

Ahi (Thunnus albacares and Thunnus obesus)

The “Ahi” category is defined as both yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus) fisheries combined. All purse seine sources were removed from Figure 1 because net-caught tuna can be damaged during harvest and sushi buyers usually steer clear of these landings. Longline and handline gear types are preferable for quality.

Within this category are major sustainability risks, both environmental and social. High seas longline fisheries can lack managerial oversight, increasing the possibility of overfishing, unreported bycatch of sensitive species, and human rights abuses.

But, there is an enormous variety of ahi sources on the market—many of which are environmentally sustainable. One example is the “Good Alternative” rated Hawaii pelagic longline fishery that primarily targets bigeye with deep-set longlines in the Hawaiian archipelago and the Eastern Pacific Ocean between California and Hawaii. In 2020, this fishery landed 16.7 million pounds of bigeye tuna (about 90% of all U.S.-caught bigeye), and nearly all of it fit the quality criteria for sushi buyers. A few vessels will land in southern California too, and sustainable bigeye can be delivered directly to your door in the San Diego area.

A unique consideration for ahi is the specter of oxidation. Red tuna loins turn brown from oxidation shortly after being cut. Since nobody wants a brown piece of tuna sashimi, the meat must be frozen quickly at very low temperatures to preserve color. Unlike Japan, the US does not have the “cold chain” (cold meaning at least -34 degrees C) to mitigate oxidation all the way to the end-user. Carbon monoxide (CO) treated tuna is therefore very common in the US sushi industry. The majority of these CO-treated tuna products are cheap and imported with minimal traceability. Many lower-priced sushi restaurants in the US rely on these tuna products.

Ahi is the most popular sushi species globally and, unfortunately, also the trickiest category to assess for environmental sustainability at the point of sale. Traceable, sustainable ahi is almost always more expensive, so we view this category as a special treat worth the extra money to avoid dubious cheap imports.

Atlantic Salmon (Salmo salar)

Farmed Atlantic salmon is the preferred salmon species for most raw preparations because it is fattier than most wild salmon, it is available year-round with consistent quality and price, and unlike wild salmon, which typically must be frozen before serving to kill any parasites, farmed salmon does not.

Figure 1 combines all Aquaculture Stewardship Council (ASC) certified Atlantic salmon production worldwide in one single source. ASC production of Atlantic salmon was measured at 1,516,489 tons annually (May 2022) across 508 farm sites globally. That total grew 50% since January 2021. ASC certified products now account for over 50% of global Atlantic salmon production, and more farms continue to seek ASC certification as more retailers in North America and Canada make environmental sustainability commitments linked to eco-certifications.

Within the subset of uncertified farmed Atlantic salmon on the market, there are 22 “Best Choice” or “Good Alternative” sources according to Seafood Watch and other environmental certifications that Seafood Watch does not recognize, like Best Aquaculture Practices (BAP).

It can be tricky to assess the source without a certification, however, since Seafood Watch ratings for Atlantic salmon are associated with obscure regions within countries like Norway and Chile that aren’t consistent with geographical information used in the salmon industry (most seafood vendors don’t refer to “Area 12: West Finnmark” when they discuss farmed salmon from northern Norway). This means a conscientious sushi diner might not have the information to make the most informed decision. But this category has come a long way in the last 15 years. Today, most global production meets a high environmental standard.

Surimi (Gadus chalcogrammus)

Surimi is the name for whitefish processed into imitation crabmeat and other seafood products. It is the main ingredient in California rolls and lower-price “seafood salads.” Surimi in North America is mostly walleye pollock (Gadus chalcogrammus) from Alaska or Russia (Russian imports accounted for 40% of all pollock sold in the US in 2017).

Over 80% of the total walleye pollock catch in Russia is from MSC certified fisheries, and 100% of the Alaskan walleye pollock fishery is MSC certified. Altogether, that’s almost 2.5 million metric tons of MSC certified walleye pollock on the global market. This sushi category is very sustainable, more so than Figure 1 suggests, and does not need to be reinvented.

Shrimp

India, Ecuador, Indonesia, Vietnam, and Thailand are the top 5 exporters of shrimp to the US and account for the vast majority of shrimp consumed in the US overall, most of which is whiteleg shrimp (Litopenaeus vannamei). Of those five countries, Ecuador and Thailand received a “Good Alternative” rating from Seafood Watch, while the other three countries received “Avoid” ratings.

However, these ratings do not include ASC or BAP certified shrimp production (whiteleg or other shrimp species), meaning certified shrimp from any country is okay. These two eco-certifications account for over 1 million tons of shrimp production globally, with more farms and supply chain entities seeking certification each year.

Domestic shrimp production should not be overlooked either. The US accounts for 27 Best Choice and Good Alternative sources (almost entirely wild), 1 MSC certified fishery, and only 4 “Avoid” sources. These US shrimp products are a little more expensive, but so is good sushi. 72.8 million pounds were landed in the Gulf of Mexico in 2021.

Similar to farmed salmon, there are some inherent environmental challenges for farmed and wild shrimp sources, but the trajectory for this category is positive. If you’re willing to pay more, you are often rewarded with a sustainable product.

Yellowtail Amberjack / Hamachi (Seriola lalandi)

This category is mostly unsustainable and is not represented accurately by Figure 1. The vast majority of yellowtail sushi comes from operations in Japan, where fish are “ranched.” In fish ranching, juvenile fish (usually males) are captured from the wild, then held in captivity until they reach market size and specifications. This process robs important breeding adults from wild stocks and requires inefficient amounts of wild fish feed to fatten the product to market size (the feed conversion ratio is six to ten times worse than farmed salmon). Seafood Watch also gives low scores to this industry for chemical use and effluent impacts on surrounding habitats. Recent import data for yellowtail is hard to find, but in 2014 the FAO estimated that Japan produced 99% of commercially reported yellowtail.

Sustainable alternatives are available but struggle to compete with the consistency of ranched Japanese yellowtail. These alternatives include wild yellowtail from California or Mexico (rated “Good Alternative” depending on fishing method). Wild yellowtail is delicious and revered for raw preparations, but availability and quality are inconsistent. Sophisticated open net pen farms in Hawaii produce “kampachi,” a similar fish also in the amberjack family. A few companies based on the Big Island have earned market traction with high-end buyers. Unfortunately, the consistency, product form (Japanese ranched yellowtail comes flash-frozen in vacuum-packed sides for easy use), and price are all in favor of Japan’s yellowtail ranching industry.

Albacore (Thunnus alalunga)

The albacore tuna sushi category is similar to ahi but with fewer environmental concerns. The smaller size of albacore allows it to be caught with “pole-and-line,” which encompasses many slightly different fishing methods that all rank better in environmental sustainability than drifting longlines (the more common fishing method for ahi tuna). Albacore carries some market advantages as well – it’s cheaper than red tuna and has a pale color that can withstand some oxidization.

This does not absolve albacore from all concerns, however. Like all tuna fisheries, albacore fisheries suffer from transparency challenges that heighten environmental and human risks. About 16 million pounds of Pacific albacore was landed domestically in 2020, mainly from Washington and Oregon, amounting to less than 5% of global albacore landings.

Evaluating albacore for the sushi market is tricky because the species is often canned regardless of catch method. We can rule out purse seine landings for the ahi category because those don’t lend well to raw preparations, but all shelf-stable brands also offer “pole-caught” options for albacore options these days. You can’t definitely look at the sources for albacore on Seafood Watch’s guide and say one is definitely going to the sushi industry. Luckily, albacore caught by US fleets is a safe choice, and there are many sustainably rated and certified sources from around the world.

Eel (Anguilla japonica)

Eel sushi offerings like unagi should be avoided until further notice. Bon Appetit was correct to focus on this challenge and Chef Jay Huang is not the first chef to attempt to recreate unagi with catfish (e.g. Chef Hajime Sato of Sozai Restaurant successfully created this substitute years ago).

Wild populations of Japanese eel (Anguilla japonica) and European eel (Anguilla Anguilla) are critically endangered. From stocks, eel farms take valuable juveniles and continue to cripple recovery efforts. Seafood Watch rates American eel farmed in indoor recirculating systems and wild American eel caught in North Carolina as a “Good Alternative,” but these sources are not readily available on the market today. Much of the low-end unagi is produced abroad – sauce and all – and exported to the US fully prepared. For this reason, it is nearly impossible to find a sustainable domestic eel offering at a sushi restaurant.  

Unagi is delicious, but so are most things covered in eel sauce. Avoid eel at sushi restaurants until further notice.

Octopus (Octopus vulgaris or Octopus cyanea)

Octopus is the fastest-growing seafood species category in the United States and has been a fixture on poke and sushi menus for many years. Most sushi offerings will be common octopus (Octopus vulgaris) or big blue octopus (Octopus cyanea) and will almost always be served cooked. In 2017, the top 4 countries in octopus exports to the US were: Spain, China, Indonesia, and the Philippines. Common octopus caught by pots or traps in Spain and Portugal is the first choice for many restaurants in North America due to the quality, size, and flavor. There is an emerging market for giant pacific octopus, the most sustainable octopus species (by Seafood Watch ratings), caught predominantly in Alaska. The flavor and texture of giant pacific octopus is boosted by the higher body fat it requires to survive in cold waters, but the sheer size of them makes the creatures cumbersome to handle for smaller restaurants.

Common octopus from Spain, Portugal, and Senegal caught by pot or jig, is rated as a “Good Alternative.” While it is tough to fully assess them because of incomplete catch data from Southeast Asia for big blue octopus, these eastern Atlantic common octopus fisheries are probably most relevant to North American sushi suppliers. Choose octopus from Europe if possible, and avoid the mysterious “baby octopus” on some sushi menus (we have no idea what species that is).

Scallops

None of the scallop fisheries rated by Seafood Watch received an Avoid rating. MSC certified sources account for a significant market share. The US Atlantic sea scallop fishery (Placopecten magellanicus) landed 19,731 metric tons in 2020. Those “Hokkaido sea scallops” (Mizuhopecten yessoensis) on your local sushi menu are from their own MSC certified fishery that reported an impressive 372,481 metric tons in 2018. Farmed “bay” scallops are considered at least “Good Alternative” worldwide.

Wild-caught scallops prove that bottom trawling can be a highly sustainable fishing method, and their farmed counterparts are one the most environmentally considerate foods on earth. Enjoy your scallop nigiri with a clean conscious.

This review and buying guide addendum is anecdotal; some readers may have other opinions on the relative representation of certain species on sushi menus. Our review is simply to demonstrate that there are ample environmentally sustainable options for almost all kinds of sushi.

If you’re skeptical about putting sustainable sourcing adjustments into action, look to Albertsons Companies, the fourth largest grocery store chain in North America, for an encouraging case study. Their “Top 5 by 2022” commitment aimed to source all tuna, salmon, shrimp, and imitation crab meat sushi products within “policy” by year-end 2022. The commitment included the removal of all eel products from the sushi department. In June 2021 (18 months ahead of schedule), Albertsons Companies announced it met this commitment.

We should applaud chefs who are rethinking their sushi menus and innovating new derivatives for delicious sushi flavors. Unfortunately, that model is not realistic for most sushi restaurants and, frankly, not necessary. There are many unsustainable land mines on a typical sushi menu, but damning the entire industry altogether is not fair or helpful.

Sushi in America does not need reinvention, but would benefit from informed sourcing, increased consumer transparency, and articles that guide diners to the right choices instead of scaring them away from sushi entirely. Sushi as we know it will be just fine.

Jack Cheney

Jack Cheney

Jack has sourced, sold, cooked, and sustainably certified seafood over the past 10 years. In addition to his contributions to Sustainable Fisheries UW, he is working to increase traceability into supply chains and educate consumers, chefs and retailers on the value of environmentally sustainable seafood. He earned a Master's in Marine Affairs from the University of Washington in 2015.

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