Geoduck Clam Farms Spread along Coastal Northwest Geoduck farms are spreading around the coastal Northwest. The geoduck, the largest clam in North America, has a three-foot neck and can live to be more than 150 years old. Divers have long harvested the delicacies from the salt waters of Washington, Alaska and British Columbia. Now -- like oysters and other shellfish -- they're being farmed by entrepreneurs. Hear Austin Jenkins from Olympia, Wash.