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Yellowstone Cutthroat Trout (Oncorhynchus Clarkii Bouvieri)

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Yellowstone Cutthroat Trout (Oncorhynchus Clarkii Bouvieri) Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri) Data: Range-wide status assessment of Yellowstone Cutthroat Trout (2001, 2007, 2016) Memorandum of Agreement for Conservation and Management of Yellowstone Cutthroat Trout (2002) Partners: Idaho Department of Fish and Game, Montana Fish, Wildlife & Parks, Nevada Department of Wildlife, Utah Division of Wildlife, Wyoming Game and Fish Department, US Fish and Wildlife Service, US Forest Service, US Bureau of Land Management, US Na- tional Park Service, US Geological Survey, Crow Tribe of Indians, Trout Unlimited, Montana Trout Unlimited, Friends of the Teton River, Western Native Trout Initiative Photo credit: Mark Smith. ii | Western Native Trout Status Report - Updated June 2019 YELLOWSTONE CUTTHROAT TROUT (Oncorhynchus clarkii bouvieri) | III Introduction Historical and Current Compared to the historical distribution, the streambed, which Yellowstone Cutthroat Trout current distribution of Yellowstone Cutthroat require for spawning. Streams without accumu- The Yellowstone Cutthroat Trout (Oncorhyn- Distribution Trout is a substantial reduction of occupied lation of fine sediment produce more inverte- chus clarkii bouvieri) is one among a diversity of stream habitat (Figure 1), but the amount of brates, which is an important food source for trout native to the western United States. They Yellowstone Cutthroat Trout are native to the occupied lake habitat has increased markedly. Yellowstone Cutthroat Trout. Shading and occupy waters in Wyoming, Idaho, Montana, Yellowstone and Snake River watersheds, a Stream habitat decreased from about 17,800 channel maintenance reduce the surface area of Utah, and Nevada. Like all cutthroat trout, distribution that crosses the Continental Di- miles to 7,500 miles, meaning Yellowstone stream exposed to sunlight, which keeps water Yellowstone Cutthroat Trout sport a red slash vide (Figure 1) . Historically, or pre-European Cutthroat Trout occupy 43% of their historical cooler. settlement, Yellowstone Cutthroat Trout were stream habitat. Stocking mountain lakes for along their jawline. They tend to be golden Yellowstone Cutthroat Trout use a range of present in an estimated 17,800 miles of stream. recreation has expanded the number of occu- brown with relatively large, dark spots con- habitat types and need to be able to swim This distribution included large parts of Wyo- pied lakes supporting Yellowstone Cutthroat centrated towards the tail. The Fine-Spotted throughout their home range. Yellowstone Cutthroat Trout is another form of Yellowstone ming, Montana, Idaho, with a few streams sup- Trout from 61 to more than 230. Cutthroat Trout vary by population in the type Cutthroat Trout, and as the name suggests, porting Yellowstone Cutthroat Trout extending The pattern of reduction of occupied stream of habitat they need. The fish in Yellowstone a dense distribution of small spots covers its into small portions of Utah and Nevada. Yel- habitat is a general contraction towards the Lake have an adfluvial life history strategy flanks. This stunning fish lives alongside Yel- lowstone Lake, at 90,000 acres, was by far the center of its historical range (Figure 1). Much meaning they live mostly in the lake, but spawn lowstone Cutthroat Trout in the Snake River largest lake available to Yellowstone Cutthroat of this habitat is at high elevation and is in in streams feeding the lake. Yellowstone Cut- drainage. The potential for the Fine-Spotted Trout. Occupied lake habitat was otherwise areas likely to remain resilient to climate throat Trout in larger rivers, like the Yellow- Cutthroat Trout to be a separate subspecies limited, with 61 lakes providing a cumulative change. Small, isolated populations remain stone River, spawn in smaller tributary streams, has been the subject of speculation; however, 35,700 acres of lake. Many high mountain on the fringe of the historical distribution. which is the fluvial life history strategy. Their genetic analyses do not support this idea. The lakes formed by glaciers were inaccessible, with These isolated populations are at elevated risk fry drift into the Yellowstone River soon after fine-spotted form is considered a Yellowstone waterfalls forming passage barriers. Cutthroat Trout in management; however, the of disappearing. Isolation from neighbors can hatching. In smaller watersheds, the resident status of this form is monitored separately. lead to inbreeding with disruption of gene flow, Yellowstone Cutthroat Trout are less migratory, and prevent recolonization of habitat where but still need access to spawning habitat within Yellowstone Cutthroat Trout have disappeared extreme flooding or wildfire kills the occupant a watershed. In smaller watersheds, Yellow- from a substantial portion of their historical fish. stone Cutthroat Trout are less migratory but range and are less abundant in some waters still need access to a variety of habitat types for they still occupy. State and federal agencies as- Habitat Requirements spawning, rearing, summer and fall residence, sign Yellowstone Cutthroat Trout special status and surviving the winter. as “species of concern” or “sensitive species”. The In streams and rivers, Yellowstone Cutthroat state and federal agencies in states supporting Trout have habitat similar requirements to Except for Yellowstone Lake, which provides Yellowstone Cutthroat Trout formed the In- most trout, but they are more sensitive to substantial habitat to adfluvial Yellowstone terstate Yellowstone Cutthroat Trout Steering habitat damage, warmer water temperatures, Cutthroat Trout, lake habitat was historically Committee in 2000. Among the committee’s and sedimentation than nonnative trout. A limited. Expansion of the distribution of Yel- responsibilities are to continually update a cen- healthy, functioning riparian area is an essential lowstone Cutthroat Trout into high mountain tralized database containing data on distribu- component of stream health. Trees, shrubs, and lakes for recreation has provided more lake tion, genetic status, and threats to Yellowstone herbaceous plants along the bank maintain the habitat, as has creation of reservoirs. To sustain Cutthroat Trout. The information reported Figure 1. The distribution of Yellowstone Cutthroat stability of stream channels, protect banks from self-reproducing populations, these lakes need here comes from this multi-state, multi-agency Trout crosses the Continental Divide. erosion, and provide shade and overhead cover. inlet or outlet streams with gravel suitable for collaboration and reflects the most recent data By reducing erosion and filtering sediment, spawning. (Endicott et al. 2016). riparian vegetation helps maintain a clean iv | Western Native Trout Status Report - Updated June 2019 YELLOWSTONE CUTTHROAT TROUT (Oncorhynchus clarkii bouvieri) | V Reproduction lowstone National Park. Each state within the gan in the late 1800s, and billions were stocked became less suitable for the sensitive Yel- historical range of Yellowstone Cutthroat Trout in waters occupied by Yellowstone Cutthroat lowstone Cutthroat Trout through pollution, Yellowstone Cutthroat Trout are spring spawn- manages them as a game fish and have regula- Trout for decades before this practice ended. warmer temperature, and damaged habitat. ers and spawn from May through July. Yel- tions in place to prevent overharvest. In many Through much of its historical range, the Brook Trout are currently the greatest threat lowstone Cutthroat Trout are locally adapted places, mandatory catch and release regulations prolonged onslaught of Rainbow Trout stocked to Yellowstone Cutthroat Trout in headwater to the waters in which they evolved, so popula- are in place. Where fishing pressure is unlikely into Yellowstone Cutthroat Trout habitat streams. Brook Trout excel at invading new tions vary in timing of their spawning runs, to have population level effects, some harvest is eventually swamped out Yellowstone Cutthroat habitat, and they share much of the habitat and the habitat they select, and the factors that cue allowed. Yellowstone Cutthroat Trout planted Trout genes. food needs as Yellowstone Cutthroat Trout. their spawning. The most typical high-quality in high mountain lakes are usually managed as Although stocking of Rainbow Trout into Brook Trout invasion often results in the quick spawning habitat is in the tails of pools, where recreational fisheries, and state fishing regula- waters supporting Yellowstone Cutthroat Trout disappearance of Yellowstone Cutthroat Trout. clean gravel swept with surface water and an tions allows limited harvest. Anglers should has ceased, their nonnative genes continue to Fall spawning may be a substantial factor upwelling of water provides ideal habitat for always check fishing regulations for the waters threaten Yellowstone Cutthroat Trout with contributing to the rapid loss of Yellowstone females to dig redds and for the embryos to they are fishing. When in doubt, release them some populations having variable levels of Cutthroat Trout following Brook Trout inva- incubate and emerge. unharmed with minimal handling. hybridization. Hybridization eventually leads to sion. Brook Trout fry emerge in late winter or In the Yellowstone River, Yellowstone Cut- Threats the loss of the features that make Yellowstone early spring, and these fish have several months throat Trout spawn in tributaries. They time Cutthroat Trout distinctive. Also, although of growth before Yellowstone Cutthroat Trout their spawning when spring runoff in the
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