# Atlantic Bluefin Tuna (*Thunnus thynnus*)

> The Atlantic bluefin tuna (Thunnus thynnus) is a powerful, warm-blooded fish built for speed, reaching about 3 m (10 ft) long and up to 450 kg (990 lb). It swims across the open Atlantic and Mediterranean at bursts of up to 70 km/h (43 mph), hunting fish and squid. Bluefin are among the longest-lived tuna, surviving 35 to 50 years. The IUCN lists the species as Least Concern.

- **Category:** Fish
- **Conservation status (IUCN):** Least Concern
- **Range:** Open waters of the Atlantic Ocean and Mediterranean Sea, migrating between cold feeding grounds and warm spawning areas.
- **Canonical page:** https://globalanimalguide.org/animals/bluefin-tuna/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Actinopterygii
- **Order:** Scombriformes
- **Family:** Scombridae
- **Genus:** Thunnus

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Thunnus thynnus |
| Diet | Carnivore (fish and squid) |
| Habitat | Open Atlantic Ocean and Mediterranean Sea |
| Lifespan | 35–50 years |
| Length | 2–3 m (6.5–10 ft) |
| Top speed | Up to 70 km/h (43 mph) |
| Conservation status | Least Concern (IUCN) |

## Size and body

The Atlantic bluefin is the largest of all tuna, typically 2 to 3 m (6.5 to 10 ft) long and weighing up to around 450 kg (990 lb). Its torpedo-shaped body is metallic blue above and silvery below, tapering to a stiff, crescent-shaped tail built for thrust. Fins fold into grooves along the body to cut drag, and a row of small finlets runs down the tail to smooth the flow of water. Every part of its shape is tuned for fast, sustained swimming.

## A warm-blooded fish

Unlike almost all other fish, bluefin tuna are partly warm-blooded, keeping their muscles, eyes, and brain warmer than the surrounding sea. A special network of blood vessels acts as a heat exchanger, trapping warmth generated by their swimming muscles. This gives them the power to hunt efficiently in cold northern waters that would slow a cold-blooded fish. It is one of the key adaptations behind their remarkable speed and endurance.

## Speed and swimming

Bluefin tuna are among the fastest fish in the ocean, capable of swimming in bursts of up to 70 km/h (43 mph). They swim almost constantly, driving themselves forward with a stiff, powerful tail while the rest of the body stays rigid. This continuous motion also pushes water over their gills, so they must keep moving to breathe. Their stamina lets them migrate thousands of kilometres across the Atlantic each year.

## Hunting and diet

Bluefin are fast, opportunistic predators that hunt schooling fish such as herring, mackerel, and anchovies, along with squid and crustaceans. They often hunt in groups, using their speed to chase down and pick off prey from tightly packed shoals. Young bluefin feed lower down the food chain, while large adults take bigger, faster fish. Their excellent eyesight helps them track prey in the open water.

## Migration and lifespan

Atlantic bluefin are long-distance travellers that cross the ocean between feeding grounds and warm spawning areas such as the Gulf of Mexico and the Mediterranean Sea. They are also long-lived for a fish, reaching ages of 35 to 50 years. Individuals may repeat the same vast migratory loops year after year, guided partly by water temperature. Tagging studies have tracked single fish swimming back and forth across the entire Atlantic.

## Fishing and conservation

The Atlantic bluefin is one of the most valuable fish in the world, prized for sushi and sashimi, and heavy fishing once pushed some populations to worrying lows. Tighter catch quotas and international management have since allowed numbers to recover, and the IUCN now lists the species as Least Concern. Careful monitoring remains important, because demand is high and the fish is slow to mature. Well-managed fisheries are central to keeping the population stable.

## Frequently asked questions

### How big do Atlantic bluefin tuna get?

Atlantic bluefin tuna typically grow 2 to 3 m (6.5 to 10 ft) long and can weigh up to around 450 kg (990 lb), making them the largest of all tuna species.

### How fast can a bluefin tuna swim?

Bluefin tuna can swim in bursts of up to 70 km/h (43 mph). Their torpedo-shaped bodies and crescent-shaped tails make them one of the fastest fish in the ocean.

### Are bluefin tuna warm-blooded?

Partly, yes. Bluefin tuna keep their muscles, eyes, and brain warmer than the surrounding water using a built-in heat exchanger, which helps them hunt in cold seas.

### What do bluefin tuna eat?

Bluefin tuna are carnivores that hunt schooling fish such as herring, mackerel, and anchovies, as well as squid and crustaceans. They often hunt cooperatively at high speed.

### How long do bluefin tuna live?

Atlantic bluefin tuna are long-lived, reaching ages of 35 to 50 years. Because they mature slowly, populations can take time to recover from heavy fishing.

### Are bluefin tuna endangered?

The IUCN currently lists the Atlantic bluefin tuna as Least Concern after populations recovered under tighter catch quotas. Continued management is still important because of high fishing demand.

## Sources

- [IUCN Red List — Thunnus thynnus.](https://www.iucnredlist.org/search?query=Thunnus%20thynnus&searchType=species)
- [Animal Diversity Web — Thunnus thynnus. University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Thunnus_thynnus/)
- [Wikipedia — Atlantic Bluefin Tuna.](https://en.wikipedia.org/wiki/Atlantic_bluefin_tuna)

---
Source: Global Animal Guide (https://globalanimalguide.org/animals/bluefin-tuna/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.