Fisherman aboard the FV Supplement cooperate with scientists to count the giant bluefin tuna.

In "Rocking the Bluefin Boat," Alan learns how Giant bluefin tuna travel vast distances every year, spawning in the Gulf of Mexico in the spring before heading up to feed off the coast of New England for the summer. Across the Atlantic, they spawn in the Mediterranean and feed off the coast of Africa.

Mediterranean countries have fished for bluefin for centuries, but in the western Atlantic, Americans rarely caught them until the 1970's, when the demand for sushi skyrocketed. Weighing in at up to 1500 pounds, a single fish may be worth thousands of dollars to a lucky fishermen. Around the same time, industrial fishing methods were adopted in the eastern Atlantic and Mediterranean. As with many other fish species, catch quotas had to be imposed. But biologists couldn't really determine just how many fish were in the sea. Were the individuals seen off New England the same globe-trotting tuna in the Mediterranean?

Molly Lutcavage used satellite data to track the migration of the giant blurfin tuna.

By tagging tuna with high-tech satellite tags, New England Aquarium biologist Molly Lutcavage is helping to sort it all out. She persuades recreational and professional fishermen to attach tags to some of their catch, and then release the fish. The tags record where the tuna go before automatically popping off the fish at a pre-determined date, then uploading their data to satellites.

Lutcavage has been studying the giant bluefin since 1993. So far, her efforts indicate that up to 65,000 giant bluefin gather in the Gulf of Maine in summer, more than three times the official estimate for the entire western Atlantic. This surprise result kept regulators from cutting the American commercial bluefin quota in half.

But the satellite tracking results -- from Stanford University and Italian groups, as well as from Lutcavage's group -- also revealed that the giant bluefin ranges across the entire north Atlantic and Mediterranean. In particular, some fish from the western Atlantic have been shown to travel several thousand miles into the eastern Atlantic and Mediterranean, where fishing quotas are probably unsustainable - more than 20 times higher than in the western Atlantic. That's a problem politics - not science - will have to resolve, but meanwhile bluefin tuna research will no doubt continue to keep the surprises coming.

For more on this topic, see the web feature:
Fishy Figures
Sea Change