Tracking the mighty, mysterious Bluefin Tuna. Living on Earth’s Jeff Young tags along on a tuna tagging expedition. Science is slowly unlocking the secrets of the Atlantic Bluefin, a highly evolved swimming machine that’s highly coveted for the sushi market. After decades of overfishing and an oil spill in its spawning grounds, there are now signs of hope that the Bluefin can bounce back.

Photo: High-tech tags let scientists follow the tuna’s wide-ranging migration. Dr. Molly Lutcavage says not all the big Bluefin go to the Gulf of Mexico. Maybe they have a secret spawning ground? (Photo: Paul Murray Courtesy of Large Pelagics Research Center)