American Oceans

How Long Do Bluefin Tuna Live?

How long do bluefin tuna live? One of the ocean’s most efficient swimmers, the bluefin tuna can live for many years, but exactly how many depends on the species of bluefin tuna in question.

school of bluefin tuna swimming in the ocean

There are three species: Atlantic, Pacific, and Southern, and all three are fast swimmers and deep divers. They hunt in schools and have highly acute vision.

These pelagic (saltwater-dwelling) fish are also sought to varying degrees as food for human consumption, which has tended to cut down on the lifespan of bluefin tuna.

Average Lifespan of Bluefin Tuna 

While a bluefin tuna can live up to 40 years, that’s certainly not an average, and that figure doesn’t represent an average bluefin tuna lifespan.

There are three species— Atlantic, Pacific, and Southern— each with its own distinguishing features. However, each species is readily identifiable as a bluefin tuna due to its unique blue and black coloring.

When bluefins are born, they are mere millimeters in length, and in only a few years (depending on the species), they grow to be hundreds of pounds. This growth requires a high metabolism and a lot of hunting for food to fuel it. 

All three species are carnivores and sit near the top of the food chain. Bluefins eat other fish, crustaceans, and even squids and other mollusks, and seem to prefer prey they can swallow whole.

Bluefins are torpedo-shaped and, as a result, are very fast swimmers. They are migratory creatures, and all are subject to overfishing.

So, how long do bluefin tuna live? Let’s take a look at each of the three species one by one.

Atlantic Bluefin

True to its name, the Atlantic Bluefin (Thunnus thynnus) lives in the Atlantic Ocean. That’s a lot of ground to cover, so this is a highly migratory species. Part of what contributes to that is that Atlantic bluefin tuna must constantly swim, like a shark, to breathe.

While they swim in all parts of the Atlantic, heavy fishing occurs in the Mediterranean. However, that is not the only place people fish for them since, as mentioned, they are quite popular as food. Business figures in, as well.

One Atlantic bluefin tuna can fetch more than $1 million. Many fishermen can willingly overlook endangered species regulations in the face of a payoff that size.

Atlantic bluefin tuna live an average of 15 years, reaching full maturity after five years. Once they reach adulthood, they spawn in the Gulf of Mexico and the Mediterranean in the spring months.

Scientists have documented the Atlantic bluefin’s homing abilities, tracking specific fish which returned to spawn in the exact same location every year. They live in Atlantic waters as far north as off the coast of Newfoundland.

They grow to about 10 feet long and can weigh up to 2,000 lbs, though an average weight is closer to approximately 500 lbs. These dimensions make them the biggest of the bluefin, and their size makes them prized as prey for sport fishermen in addition to those fishing for food. 

They are primarily blue and black with two dorsal fins, the second one reddish-brown in color. Atlantic bluefin tuna occupy a spot on the endangered species list.

Pacific Bluefin

Scientists didn’t differentiate between Atlantic and Pacific bluefin tuna for many years. Pacific bluefin (Thunnus orientalis) also sport blue and black coloring, but they have silver and gray accents on their bellies and have a series of small, yellow fins on their backs in addition to their dorsal ones.

They are considerably smaller than their Atlantic counterparts, growing to about five feet long and weighing around 130 lbs. This size difference extends to their eyes, which are appreciably smaller than those of the Atlantic bluefin. 

Because they are so much smaller, Pacific bluefin do not get pursued as aggressively by fishermen. Still, they have been subject to overfishing, and while they aren’t endangered, they are considered vulnerable.

While scientists have documented some living as long as 26 years, Pacific bluefin tuna live for an average of about 15 years, like the Atlantic bluefin. 

True to their name, these bluefins live in the Pacific Ocean, spending much of their lives off the coast of California. As a result, when people fish for Pacific bluefin, that’s where they go.

Southern Bluefin

Like the other bluefin species, the Southern bluefin (Thunnus maccoyii) can regulate its body temperature in a manner unusual among fish.

Using a specialized blood vessel construction known as a countercurrent exchanger, they can change their body temperature by up to ten degrees above or below the ambient water temperature. As a result, they can withstand more extreme water temperatures than most other bony fish.

Swimming in the southern hemisphere means encountering cold waters. The Southen bluefin can flourish in waters as cold as 37° F. While they generally don’t dive as deep as the other bluefins (usually only 2,500 feet), their imperviousness to colder temperatures remains unrivaled.

They average about eight feet in length and weigh about 260 lbs. They very much resemble the Pacific bluefin tuna in appearance. The main difference between the two is the Southern bluefin’s first dorsal fin, which is yellow or blue.

Their average lifespan runs about 30 years, but they don’t reach maturity until about the age of 12. When they spawn, they do it in the Indian Ocean, off the northwest coast of Australia.

Final Thoughts

The bluefin tuna swims along as, if not the king of the ocean, at least a member of the court. Due to their size (specifically the Atlantic bluefin), speed, ability to regulate their body temperatures, and deep diving, they can do more in the water than many other fish.

So, to recap how long bluefin tuna live, while bluefin tuna can live as long as 40 years or more, such a figure stands as an outlier. Pacific and Atlantic bluefin live an average of 15 years, while the smaller southern bluefin tuna lives a slower life, maturing later than the other two but averaging about a 30-year lifespan.

WIthout continued protections afforded to them from being listed as vulnerable or endangered species, the bluefin’s lifespan will dwindle to zero, as extinction would be the inevitable result of continued overfishing.

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