ALONG THE SELWAY RIVER, Idaho — As a helicopter gunship pilot in Vietnam, Steve Pettit had no rod and reel, so he fished with grenades — a blunt technique for an angler who went on to become a biologist and a champion for Columbia River salmon and steelhead. "I dedicated my whole career to trying to save them," Pettit said. "I thought I would retire before the fish went down. ... It's pretty depressing."