In Discovery's all-new two part special "Fighting Tuna", four captains vie for these high stakes fish using boats only a third the size of Bering Sea trawlers. Tossed by high waves and rough weather, they face down the world's most powerful fish, an adversary capable of highway speeds. The payoff? A single fish can sell for $10,000. It's the biggest prize in the sea - Giant Bluefin Tuna. Weighing in between 320 and 1,500 pounds, these behemoths are the most expensive fish in the world, their price driven up by Japanese demand for sushi. The largest tuna swim north to the icy waters of the Atlantic Ocean where they're caught the old-fashioned way: with rod and reel.