Ascension Island in the South Atlantic Ocean: everything that lives or stops here is either hunter or hunted. Every Easter it plays host to one of nature's greatest showdowns in its crystal-blue waters when yellow-fin tunas stop by on their migration across the Atlantic. Weighing over 800 pounds, they are a favourite meal for sharks...if they can catch them. Tunas are predators and often faster, fitter and bigger than the sharks. Who will win?