Yellowstone Cutthroat Trout (Oncorhynchus clarki bouvieri)

What is the Yellowstone cutthroat trout? Yellowstone cutthroat trout (YCT) is one of several subspecies of cutthroat trout native to the Rocky Mountain region. It often exhibits bright yellow, orange, and red colors and is generally distinguishable from other inland subspecies of cutthroat trout by the particular pattern of black spots that appear on the body.

Where are YCT found? The historic range of YCT generally consists of the waters of the Snake River drainage (Columbia River basin) upstream from Shoshone Falls, Idaho, and those of the Yellowstone River drainage (Missouri River basin) upstream from and including the Tongue River, in eastern Montana. Historic range in the Yellowstone River drainage thus includes large regions of Wyoming and Montana, whereas that of the Snake River drainage includes large regions of Wyoming and Idaho and small parts of Utah and Nevada. Today, various YCT stocks remain in each of those major river drainages in Montana, Wyoming, Idaho, Utah and Nevada.

What do YCT eat? YCT feed primarily on macroinvertebrates, particularly immature and mature forms of aquatic insects, terrestrial insects, and, in lakes, zooplankton. These preferences for macroinvertebrates occur at all ages in both streams and lakes. YCT rarely feed on other fishes.

What is the life cycle of YCT? YCT usually reach maturity at 4 or 5 years of age. Spawning occurs primarily in small tributary streams between March and July, when water temperatures reach about 50 F. Fertilized Yellowstone cutthroat eggs are deposited in stream gravels where they incubate for several weeks, the actual period of time dependent upon water temperature. Several days after hatching from the egg, when about one inch long, the fry emerge from the gravel and disperse into the stream. The fry may grow to maturity in the spawning stream or they may move downstream and mature in larger rivers or lakes. Thus three YCT life-history types are recognized: Resident fish spend their lives entirely in the tributary; fluvial fish spawn in small tributaries and their resulting young migrate downstream to larger rivers where they grow and mature; and adfluvial fish spawn in streams but grow and mature in lakes.

How big do YCT get? Growth of individual YCT, like that of fish of other species, depends largely upon the interaction of food availability and water temperature. Resident YCT usually do not grow longer than 30 cm (12 inches), presumably because they spend their entire lives in small, coldwater tributaries. In contrast, fluvial and adfluvial YCT often grow longer than 30 cm (12 inches) and attain weights of 0.9-1.4 kg (2-3 pounds). Such rapid growth results from the warmer, more-productive environments afforded by large rivers, lakes, and reservoirs.

Where do most YCT remain today? Most of the habitat for extant YCT stocks lies on lands administered by federal agencies, particularly the U.S. Forest Service and National Park Service, principally in Montana, Wyoming and Idaho. Moreover, many of the strongholds for YCT stocks occur within roadless or wilderness areas or Yellowstone National Park, all of which afford considerable protection to YCT.

What is being done to protect YCT? There are numerous federal and state regulatory mechanisms that protect YCT and their habitats throughout the range of the subspecies. In addition, the U.S. Forest Service, state game and fish departments, and National Park Service reported numerous ongoing projects directed toward the protection and restoration of YCT and their habitats.

Does the Service offer any recommendations regarding the management of YCT? The Service strongly recommends that state game and fish departments, federal land-management agencies, tribal governments, private groups, and other concerned entities continue to work individually and cooperatively to develop and implement programs to protect and restore stocks of YCT throughout the historic range of the subspecies.