Yellowstone has 11 fish native to its lakes and streams. Native sport fish include three subspecies of cutthroat trout, fluvial arctic grayling, and mountain whitefish. Non-native fish species that were introduced to the park in the late 19th and early 20th centuries include rainbow trout, brown trout, brook trout, and lake trout. Although non-native trout are also important to the angler experience in Yellowstone, they have contributed to a decline in the park’s native cutthroat trout and fluvial arctic grayling.