Atlantic Bluefin Tuna

The Atlantic bluefin tuna is one of the largest, fastest, and most gorgeously colored of all the world’s fishes. Their torpedo-shaped, streamlined bodies are built for speed and endurance. Their coloring—metallic blue on top and shimmering silver-white on the bottom—helps camouflage them from above and below. And their voracious appetite and varied diet pushes their average size to a whopping 6.5 feet (2 meters) in length and 550 pounds (250 kilograms), although much larger specimens are not uncommon.

Unfortunately for the species however, bluefin meat also happens to be regarded as surpassingly delicious, particularly among sashimi eaters, and overfishing throughout their range has driven their numbers to critically low levels.

Atlantic bluefins are warm-blooded, a rare trait among fish, and are comfortable in the cold waters off Newfoundland and Iceland, as well as the tropical waters of the Gulf of Mexico and the Mediterranean Sea, where they go each year to spawn. They are among the most ambitiously migratory of all fish, and some tagged specimens have been tracked swimming from North American to European waters several times a year.

They are prized among sport fishers for their fight and speed, shooting through the water with their powerful, crescent-shaped tails up to 43 miles (70 kilometers) per hour. They can retract their dorsal and pectoral fins into slots to reduce drag. And some scientists think the series of “finlets” on their tails may even serve to reduce water turbulence.

Bluefins attain their enormous size by gorging themselves almost constantly on smaller fish, crustaceans, squid, and eels. They will also filter-feed on zooplankton and other small organisms and have even been observed eating kelp. The largest tuna ever recorded was an Atlantic bluefin caught off Nova Scotia that weighed 1,496 pounds (679 kilograms).

Bluefin tuna have been eaten by humans for centuries. However, in the 1970s, demand and prices for large bluefins soared worldwide, particularly in Japan, and commercial fishing operations found new ways to find and catch these sleek giants. As a result, bluefin stocks, especially of large, breeding-age fish, have plummeted, and international conservation efforts have led to curbs on commercial takes. Nevertheless, at least one group says illegal fishing in Europe has pushed the Atlantic bluefin populations there to the brink of extinction.