Mountain whitefish are native to a wide range of cold-water rivers in western North America from the Northwest Territories through the Pacific Northwest, the Hudson Bay and Missouri River basins, into Nevada and Utah. Mountain whitefish are born and mature in freshwater rivers. These native fish spawn during late fall. Their eggs hatch after 6-10 weeks, typically in early spring. Mountain whitefish will often live 7-9 years. Mountain whitefish do not die after spawning.