Bluefin Tuna: Tasty Meal or Endangered Species?

You may have heard of bluefin tuna as a premium sushi ingredient. It's also at risk of extinction due to overfishing.

Learn more about the three bluefin tuna species.

What Is Bluefin Tuna?

Bluefin tuna is any of three large tuna (Thunnus) species: Pacific bluefin tuna, Southern bluefin tuna and Atlantic bluefin tuna. All three species are used in sushi and sashimi.

Pacific Bluefin Tuna

Pacific bluefin tuna (Thunnus orientalis) is the most expensive fish in the world. In 2019, a single fish sold for $3 million. At 612 pounds, the Pacific bluefin tuna cost over $5,000 per pound.

Some conservationists think the price wasn't high enough; Pacific bluefin tunas were declared "near threatened" by the IUCN Red List in 2021. Since the 1950s, the species has declined by almost a quarter.

Pacific bluefin tuna inhabit the eastern Pacific Ocean from the Gulf of Alaska to Baja California, Mexico, and the western Pacific Ocean from the southern Sea of Okhotsk to the northern Philippines.

Southern Bluefin Tuna

Southern bluefin tuna (Thunnus maccoyii) is the rarest of the three bluefin tuna species. It was declared critically endangered by the IUCN Red List in 1996, but has moved down to endangered status as of 2021.

Southern bluefin tuna live in the southern parts of the Atlantic, Indian and Pacific Oceans. One conservation issue may be that fishing limits are set by weight of the catch, but a common practice is catching wild juveniles and fattening them up in captivity.

Atlantic Bluefin Tuna

Atlantic bluefin tuna (Thunnus thynnus), also known as the northern bluefin tuna or giant bluefin tuna, is the most abundant and largest of the three bluefin tuna species. A 1,496-pound (678.58 kg) adult Atlantic bluefin caught in Nova Scotia, Canada, in 1979 set the International Game Fish Association record for largest tuna ever caught.

Although Atlantic bluefin tuna face overfishing just like Pacific and Southern bluefins, the global population has not faced a major decline in the past three generations and therefore its IUCN Red List Status is "least concern."

There are two major populations of Atlantic bluefin tuna:

  • Eastern Atlantic stock: These fish live in the eastern Atlantic ocean and spawns in the Mediterranean Sea. The eastern Atlantic population comprises 80 percent of the global population and may be increasing.

  • Western Atlantic stock: These tunas live in the western Atlantic Ocean from eastern Canada to northern Brazil and spawns in the Gulf of Mexico. This much smaller population has experienced significant decline.

Outside of spawning season, there is significant mixing of the two stocks.

In 2022, the International Commission for the Conservation of Atlantic Tunas (ICCAT) adopted its first management procedure for both stocks of Atlantic bluefin tuna, including catch limits for Atlantic bluefin fishing.

Bluefin Tuna Conservation

The huge demand for bluefin tuna in sushi markets has led to population declines of all three species. The biggest threats to bluefin tuna are overfishing and illegal fishing.

If these highly migratory species are to survive, their conservation will require international cooperation. The International Commission for the Conservation of Atlantic Tunas (ICCAT) has 52 member nations and oversees conservation of bluefin tuna and other species.

Can I Eat Bluefin Tuna?

NOAA Fisheries recommends eating U.S. wild-caught Pacific bluefin tuna and U.S. wild-caught western Atlantic bluefin because they are "sustainably managed under a rebuilding plan that allows limited harvest."

The Monterey Bay Aquarium Seafood Watch recommends avoiding all species of bluefin tuna, regardless of where they were caught or farmed.

Other Species of Tuna

There are a total of eight species of tuna (genus Thunnus), only three of which are bluefin species. The other five species of tuna are:

  • Albacore tuna (Thunnus alalunga)

  • Bigeye tuna (Thunnus obesus)

  • Blackfin tuna (Thunnus atlanticus)

  • Longtail tuna (Thunnus tonggol)

  • Yellowfin tuna (Thunnus albacares)

Original article: Bluefin Tuna: Tasty Meal or Endangered Species?

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