When it comes to sushi and seafood prestige, no fish commands more attention than bluefin tuna. We took our most pressing questions to Vancouver Aquarium Ocean Wise® research analyst Laurenne Schiller to get her insights on this iconic fish.
What is bluefin tuna?
‘Bluefin tuna’ is a generic term given to three distinct species of tuna: Pacific bluefin (Thunnus orientalis), Atlantic bluefin (Thunnus thynnus), and southern bluefin (Thunnus maccoyii). These are some of the largest fish in the ocean and sportfishing catches suggest all three species can grow to be over two metres in length and weigh several hundred kilograms.
Where does bluefin come from?
As suggested by their names, the three bluefin species inhabit different oceans and their individual distributions do not overlap. Since all three species migrate across their respective habitat ranges, they may be caught by fishing vessels in a country’s domestic coastal waters or far offshore in the High Seas.
How is bluefin caught?
The gear used to catch these tuna will vary depending on what country is fishing and where they are fishing. Generally speaking, most adult bluefin landed in the High Seas are caught with longlines, and bluefin landed closer to shore may be caught with purse seines, handlines, or harpoons.
Is it true that a bluefin sold for over $1 million?
Yes, but that isn’t typical. While all three bluefin species fetch a high price in Japan, in 2015, domestic Pacific bluefin sold for an average of $33 per kilogram and imported bluefin sold for $27 per kilogram — but the first Pacific bluefin of the year is especially important. This fish is auctioned off at Tsukiji Fish Market in Tokyo and is believed to bring the buyer prestige and good fortune for the year. In recent years, a bidding war between competing sushi restaurants resulted in abnormally high prices (the highest being $1.96 million for a 222 kg fish in 2013). In recent years, one of the restaurant owners did not participate in the bidding war and thus the winning bids have been much lower.
I’ve heard bluefin is endangered—is this true?
All three bluefin species have had their populations significantly depleted as a result of commercial fishing. Pacific and southern bluefin are in the worst shape with populations depleted by over 95 percent. Pacific bluefin has been listed as ‘Vulnerable’ on the International Union for the Conservation of Nature (IUCN) Red List, southern bluefin is listed as ‘Critically Endangered’, and Atlantic bluefin is ‘Endangered’. At present, the United States Endangered Species Act (ESA) is conducting a review for the inclusion of Pacific bluefin but none of the bluefin species are on the Canadian Species at Risk Act (SARA).
So if it’s not listed on SARA, is bluefin caught in Canada sustainable?
The only bluefin species caught in Canadian waters is Atlantic bluefin and Canada has very conservative catch limits; each bluefin license holder is allowed only one fish per season. However, all of these fish are part of the western Atlantic stock, which is under fishing pressure from multiple nations, each with their own quota.
In Canada, the process to get a species listed under SARA is complex and involves many stages. All species that get listed on SARA must first be assessed and designated ‘At Risk’ by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Once listed under SARA as ‘Endangered’, a species must be federally protected. Atlantic bluefin was assessed by COSEWIC in 2011 and designated ‘Endangered’, but has not yet been federally recognized by SARA. Since there are many stakeholders involved in the determination of a SARA listing, commercial interests often conflict with conservation goals when it comes to marine fish. In addition, it typically takes around five years between the COEWIC assessment and the decisions to list a species under SARA, during which time they receive no additional protection.
How do fishers in Canada make a living off bluefin tuna?
Most fishers in the Maritimes have licenses for multiple species and thus make money from the other species they catch, such as lobster. Also, a bluefin fisher may hold multiple licenses and each license allows the catch of one fish. DFO regulates the number of total licenses available each year and the total allowable catch of bluefin. Many fishers are allowed to operate catch-and-release tours for Atlantic bluefin, and can make money through this type of business venture as well.
Can bluefin tuna be farmed?
Farming exists for all three bluefin species, but not in the same way as other species. Rather than being farmed from eggs, most bluefin aquaculture is in the form of ranching. This process involves catching small, young bluefin in nets and bringing them alive to open net sea pens. From there they get fattened up over a four to 12 month period before being killed and exported.
This type of farming is largely unsustainable and part of the reason why the southern bluefin stock has been so heavily depleted. In catching small, young bluefin, ranching inhibits the population to recover since these fish never get a chance to reproduce and contribute to rebuilding the stock.
Does bluefin come in a can?
No. Due to its value and scarcity, bluefin is sold flash frozen or fresh. The most commonly canned tuna species available in Canada are skipjack, albacore, and sometimes yellowfin.
How do I make sure the tuna I’m ordering at a restaurant is not bluefin?
The Japanese word for bluefin is maguro and often it is listed this way on Japanese restaurant menus. The term ‘Red tuna’ may refer to bluefin but it may also be a different tuna such as bigeye. If you are in doubt, ask your server or look for the Ocean Wise symbol.
What are some sustainable alternatives to bluefin?
In general, it’s best to avoid eating fish higher on the food web as much as possible. That said, there are a variety of Ocean Wise recommended tuna alternatives. If you are looking to support Canadian fisheries, the BC troll albacore fishery is an excellent choice. Other responsibly managed tuna fisheries with low bycatch and limited impacts on the target stock include fish aggregation device (FAD)-free skipjack tuna from any ocean, or handline-caught yellowfin from the Pacific.
How can I learn more?
Want to read more about bluefin? Check out Tuna: A Love Story by Richard Ellis, Song for the Blue Ocean by Carl Safina, or Sushi Economy by Sasha Issenberg. To learn more about seafood and fisheries issues in general, Paul Greenberg’s Four Fish and American Catch are great reads, as is The Story of Sushi by Trevor Corson. As always, feel free to leave a comment with your thoughts or questions here or contact Ocean Wise staff at firstname.lastname@example.org and we will get back to you.
Overfishing is the single biggest threat our oceans face today. With more than 675 partners across Canada, Ocean Wise makes it easy for consumers to make sustainable seafood choices that ensure the health of our oceans for generations to come. The Ocean Wise symbol next to a seafood item is the Vancouver Aquarium’s assurance of an ocean-friendly seafood choice. www.oceanwise.ca.