The ones that live in lakes usually move into streams to spawn in the fall. Brown Trout are considered to be native to Europe and western Asia and were widely introduced to North America in 1883 and in 1889 to the Madison River, a prime trout stream flowing west out of Yellowstone National Park and then north to help form the Missouri River. The results of plant, fish or animal introductions are not always seen favorably. It is usually long after the fact that we become aware of the consequences. Today, keeping native ecosystems whole and free of invasive species is seen as the best way to keep those communities healthy.