Diver and Bluefin Tuna

Photograph by John Anderson, National Geographic

The silvery magnificence of Atlantic bluefin tuna (Thunnus thynnus) swims past a diver in Japan's Tokyo Sea Life Park. The fish's belly meat is prized as the finest sushi in the world; one fish can easily sell for tens of thousands of dollars on the world market. Its meat is in such demand that overfishing—some illegal—leaves the giant bluefin population at risk of collapse.