Scientist Scours Globe For Largest Freshwater Fish In Bid To Save Earth's Giants

Floating down the Mekong in his dinghy, Zeb Hogan is on the ultimate fisherman's quest: to find the world's largest freshwater fishes. The American biologist's search is to take him to 10 rivers around the globe including the Nile, Amazon and Mississippi, looking for about 20 species of hulking fish such as the goliath catfish, Chinese paddlefish and North American lake sturgeon - not to catch them, he says, but to save them.