The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the Pacific salmon (Oncorhynchus) genus. Chinook are native to the north Pacific Ocean and the river systems of western North America ranging from California to Alaska. They have been introduced to other parts of the world, including New Zealand and the Great Lakes. Historically, the native distribution of Chinook salmon ranged from as far south as the Ventura River in California and north to Alaska, as far as Kotzebue Sound. In 1967, the Michigan Department of Natural Resources planted Chinook in Lake Michigan and Lake Huron to control the alewife, an invasive species of nuisance fish from the Atlantic Ocean. The Chinook is blue-green,red or purple on the back and top of the head with silvery sides and white ventral surfaces. It has black spots on its tail and the upper half of its body. Its mouth is often dark purple to black. Adult fish range in size from 24 to 36 in (610 to 910 mm) but may be up to 58 inches (1,500 mm) in length; they average 10 to 50 pounds (4.5 to 23 kg), but may reach 130 pounds (59 kg).