Often referred to as "the Wagyu of salmon," Copper River king salmon can reach $120 per pound. Sought after by chefs for its rich, buttery flavor, this salmon is not easy to come by. To reach its final destination in Alaska's Copper River, it has to swim 300 miles between glaciers. It's a tiring journey in which the fish builds up its strength and muscle. The cold waters of the Copper River are challenging for fishers too, who set sail with no guarantee they will catch any fish at all. So is Copper River king salmon worth the challenge? And why is it so expensive?