White sturgeon are the largest freshwater fish in North America, reaching up to six feet (1.8 meters) in length and weighing up to a ton. White sturgeon were once widely distributed from Alaska to Central California, but populations are now severely depleted and large fish are very rare. White sturgeon caviar is considered a delicacy comparable to Beluga and Osetra caviar.
Source: http://www.edf.org/page.cfm?tagID=15743