Pacific bluefin tuna

Natural History

Bluefin tuna are some of the largest and fastest fish in the ocean—they're powerful swimmers, built for endurance and speed. To help conserve energy on their long-distance journeys, tuna's bodies are almost perfectly streamlined, reducing drag around their fins. And tuna can retract or fold those fins against the body so water flows more smoothly over their bodies. This makes them super-streamlined.

Unlike most fish, tuna are warm-blooded and can heat their bodies to six degrees Celsius (11 degrees Fahrenheit) warmer than the surrounding water. This added warmth helps their muscles work faster and more efficiently. Tuna consume as much as five percent of their body weight daily and must continually swim with their mouths open to force water over their gills, supercharging their blood-rich muscles with oxygen.

Pacific bluefin tuna spawn off of Okinawa; between Taiwan and the Philippines; and in the Sea of Japan. They migrate over 6,000 nautical miles (11,112 km) to the eastern Pacific, eventually returning to their birth waters to spawn.

Conservation

Avoid eating bluefin tuna; they're severely overfished throughout the world. They're caught nearly everywhere they swim, and many young bluefins are caught before they have the chance to reproduce. Visit the Seafood Watch section on our web site to learn about choosing seafood wisely.

Creating effective fishing policies for bluefin tuna is difficult since they're highly mobile and swim through the territorial waters of many nations. Data about their movements and high levels of international cooperation are needed to ensure sustainable bluefin tuna populations.

To help provide some of this data, staff at the Tuna Research and Conservation Center have been tagging both Atlantic and Pacific bluefin tunas in the wild as well as studying them in their facility, next door to the Aquarium. This research is helping inform fishing policies for bluefin tuna worldwide.

Cool Facts

A Pacific bluefin tuna is capable of swimming at speeds of 12 to 18 miles per hour (20-30 km per hour) for brief periods. 

Magnetite, a mineral found in neural pits in the tuna's snout, may be used by the tuna to detect the earth's magnetic field for navigation.