Tracking Bluefin Tuna
Electronic Tracking Devices Shed Light on Their Migration Pattern

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       by Tuna Research and Conservation Center

Aug. 17, 2001 The giant bluefin tuna is among the fastest, biggest, and most magnificent fishes on the planet. It can weigh up to 1,500 pounds. Over short distances, it can swim as fast as a horse can run. It can dive 3,000 feet in a matter of minutes, and swim across the Atlantic Ocean in 40 days.

Atlantic bluefin tuna
Atlantic bluefin tuna can reach 10 feet in length, weighing as much as 1,500 pounds.
Photo: Gilbert Ryckevorsel, Science

Barbara Block is a biologist with Stanford University, and perhaps the world's leading expert on bluefin tuna. At the Monterey Bay Aquarium in California, she has studied tuna in captivity for years.

Now, after five years of capturing tuna along the Atlantic coast and tagging them with electronic tracking devices, she has done what no one has ever done before: track the migrations of this fish across the ocean.

Her paper in this week's issue of Science magazine points out an important discovery: Tuna in the western Atlantic migrate to feeding grounds in Europe and the Mediterannean. They also travel to spawning grounds in the Gulf of Mexico and the eastern Mediterannean.

Researchers inserting an archival tag
Researchers inserting an archival tag in bluefin tuna
Photo: Gilbert Ryckevorsel, Science
View the photo gallery of Atlantic bluefin tuna


That's important because limits on tuna catches are much tighter in the western Atlantic than in Europe. What fishery managers now realize is that overfishing in Europe may be depleting the Atlantic bluefin population.

Those managers plan to use Block's findings in two weeks when experts meet to discuss lowering the allowable bluefin catch in the eastern Atlantic.

On Morning Edition, NPR's Chris Joyce takes a closer look at Dr. Block's discovery.

Other Resources

Stanford University's Tuna Research and Conservation Center

International Commission for the Conservation of Atlantic Tunas,    an intergovernmental fishery organization responsible for the    conservation of tunas

Monterey Bay Aquarium, one of the organizers for Stanford    University's tuna-tracking project