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Rocky Mountain Cutthroat Trout - Oncorhynchus virginalis
Other Names:
Blackspotted Cutthroat Trout, Yellowstone Cutthroat Trout [subspecies bouvieri],
Oncorhynchus clarkii bouvieri
State Rank Reason (see State Rank above)
The Yellowstone Cutthroat trout is currently ranked "S2" in Montana because it is at risk because of very limited and/or potentially declining population numbers, range and/or habitat, making it vulnerable to extirpation in the state.
General Description
The Rocky Mountain Cutthroat Trout ( formally Yellowstone Cutthroat Trout) is one of two species of native cutthroat found in the state. Together they have been designated Montana's state fish, the Blackspotted Cutthroat Trout. They have a golden coloration and larger spots more widely distributed on their sides than the Westslope Cutthroat Trout. The Rocky Mountain Cutthroat Trout, is native to the Yellowstone River drainage of southwest and south-central Montana. Originally their range was as far downstream as the Tongue River, but today pure, unhybridized populations are limited to some headwaters streams and Yellowstone National Park. Rocky Mountain Cutthroat Trout are a Montana Fish of Special Concern. Much of their spawning habitat in tributaries of the upper Yellowstone River has been lost to irrigation withdrawals which dewater the streams before spawning and egg-incubation are completed in July and August. The Big Timber hatchery of the Montana Department of Fish, Wildlife, and Parks maintains a pure Rocky Mountain Cutthroat Trout broodstock. Rocky Mountain Cutthroat Trout are used extensively for mountain lake stocking on the east slope of the Rocky Mountains and in the Absaroka-Beartooth Wilderness where they can grow to sizes up to 15 pounds. In general, Rocky Mountain Cutthroat Trout are larger than Westslope Cutthroat Trout and more prone to eat fish as part of their diet.
For a comprehensive review of the ecology, conservation status, threats, and management of this and other Montana fish species of concern, please see
Montana Chapter of the American Fisheries Society Species of Concern Status Reviews.Diagnostic Characteristics
The Rocky Mountain Cutthroat Trout is visually distinguished from other trout species by its two prominent red slashes on the lower jaw, and from other cutthroat trout subspecies by its medium-large, black spots that tend to be concentrated posteriorly, and its drab brownish, yellowish, or silvery coloration, with brighter colors generally absent even in mature fish (Behnke 1992, Baxter and Stone 1995,
Montana AFS Species Status Account).
Tiny teeth are usually present on the floor of the mouth behind the tongue. These are embedded in tissue and difficult to see but may be felt if brushed with the side of a needle. Red on the side of the head and gill cover becomes intense in the breeding male.
Species Range
Range Comments
Historically, Rocky Mountain Cutthroat Trout were believed to have occupied much of the Yellowstone River basin, including portions of the Clarks Fork of the Yellowstone River, Bighorn River, and Tongue River basins in Montana and Wyoming, and parts of the Snake River basin in Wyoming, Idaho, Utah, and Nevada. This species has been introduced to many watersheds in Montana where they were not native.
Observations in Montana Natural Heritage Program Database
Number of Observations: 4461
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Rocky Mountain Cutthroat Trout inhabit relatively clear, cold streams, rivers, and lakes. Optimal temperatures have been reported to be from 4 to 15 degrees C., with occupied waters ranging from 0 to 27 degrees C. (Gresswell 1995,
Montana AFS Species Status Account).
Ecology
Rocky Mountain Cutthroat Trout may live as long as 11 years (Gresswell 1995,
Montana AFS Species Status Account).
There are three primary life history patterns: resident, fluvial, and adfluvial (Gresswell 1995). Resident fish occupy home ranges entirely within relatively short reaches of streams. Fluvial fish migrate as adults from larger streams or rivers to smaller streams to reproduce. Adfluvial fish exhibit a similar pattern, but migrate, sometimes many kilometers, as mature adults from lakes to inlet or outlet streams to spawn (role of stream ice on fall and winter movements and habitat use by Bull Trout and cutthroat trout in Montana headwater streams).
Movement in Rocky Mountain Cutthroat Trout may also be associated with temporal habitat changes. At low water temperatures in winter, fry (and probably juvenile) Rocky Mountain Cutthroat Trout entered spaces in the stream bottom during the day, and emerged from them at night (Griffith and Smith 1993). Larger Rocky Mountain Cutthroat Trout may also shift habitats from fall to winter as water temperature declines and anchor and shelf ice develop (Brown and Mackay 1995, Jakober et al. 1998). Rocky Mountain Cutthroat Trout probably undergo localized movements associated with changes in habitat or food availability in other seasons (Young 1996, Young et al. 1997, 1998,
Montana AFS Species Status Account).
Reproductive Characteristics
Rocky Mountain Cutthroat Trout typically spawn in spring and early summer after flows have declined from their seasonal peak and tend to select sites with suitable substrate (gravel less than 85 mm in diameter), water depth (9 to 30 cm), and water velocity (16 to 60 cm per second) (Varley and Gresswell 1988, Byorth 1990, Thurow and King 1994). Water temperature determines the time of hatching and emergence of fry. After emergence, fry immediately begin feeding, typically in nearby stream margin habitats, but they may also undertake migrations to other waters (Gresswell 1995). Juvenile fish require three or more years to mature. Spawning fish tend to be from 200 to over 600 mm long and weigh from 0.1 to 5 kilograms (Thurow et al. 1988,
Montana AFS Species Status Account).
Management
To maintain healthy populations of Rocky Mountain Cutthroat Trout and to ensure the wide-ranging persistence of this subspecies in Montana and elsewhere, a number of tactics have been proposed in recent status assessments (Yellowstone Cutthroat Trout Working Group 1994, Gresswell 1995, May 1996, May et al. 1998, Dufek et al. 1999, Wyoming Game and Fish Department 2000). These include field surveys, harvest management, habitat protection and improvement, non-native species control, and broodstock management (
Montana AFS Species Status Account).
Stewardship Responsibility
Threats or Limiting Factors
Gresswell (1995) and Kruse et al. (2000) considered nonnative fish species the greatest threat to the persistence of Yellowstone cutthroat trout. Because Rocky Mountain Cutthroat Trout and Rainbow Trout readily hybridize and produce fertile offspring, sympatric populations often form hybrid swarms (Allendorf and Leary 1988; Henderson et al. 2000). Introductions or invasions of Brown Trout (Salmo trutta), Brook Trout (Salvelinus fontinalis) and Lake Trout (Yellowstone Lake) have led to displacement of cutthroat trout throughout the western U.S.
References
- Literature Cited AboveLegend:
View Online Publication
Baxter, G. T. and M. D. Stone. 1995. Fishes of Wyoming. Wyoming Game and Fish Department, Cheyenne, Wyoming. 290 pp.- Behnke, R.J. 1992. Native trout of western North America. Bethesda, MD: American Fisheries Society Monograph 6. pp. 175-178.
- Brown, R.S. and W.C. Mackay. 1995. Fall and winter movements of and habitat use by cutthroat trout in the Ram River, Alberta. Transactions of the American Fisheries Society 124(6): 873-885.
- Byorth, P.A. 1990. An evaluation of Yellowstone cutthroat trout production in three tributaries of the Yellowstone River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 57 p.
- Dufek, D., K. Johnson, J. Kiefling, B. McDowell, R. McKnight, S. Roth, and S. Yekel. 1999. Status and management of Yellowstone cutthroat trout Oncorhynchus clarki bouvieri. Wyoming Game and Fish Department, Cheyenne.
- Gresswell, R. E. 1995. Yellowstone cutthroat trout. Pp 36-54 In: M. K. Young, technical editor. Conservation assessment for inland cutthroat trout. USDA Forest Service Gen. Tech. Rep. RM-GTR-256. iv + 61 pp.
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- Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D. E. McAllister, J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Musuem of Natural History. 867 p.
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- May, B. E. et al. 1998. Yellowstone cutthroat trout conservation program within the state of Montana. Prepared for the Montana Department of Fish, Wildlife and Parks, Helena.
- Montana Chapter of the American Fisheries Society species status accounts.
- Scott, W.B. and E.J. Crossman. 1973. Rainbow trout, Kamloops trout, Steelhead trout Salmo gairdneri Richardson. pp. 184-191. In: Freshwater fishes of Canada. Ottawa, Canada: Fisheries Research Board of Canada, Bulletin 184. 966 p.
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- Thurow, R.E, C.E. Corsi, and V.K. Moore. 1988. Status, ecology, and management of Yellowstone cutthroat trout in Upper Snake River Drainage, Idaho. American Fisheries Society Symposium 4:25-36.
- Varley, J.D. and R.E. Gresswell. 1988. Ecology, status, and management of the Yellowstone cutthroat trout. American Fisheries Society Symposium 4:13-24.
- Wyoming Game and Fish Department. 2000. Yellowstone cutthroat trout management summary. Wyoming Game and Fish Department, Fish Division, Cheyenne.
- Young, M. K. 1996. Summer movements and habitat use by Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) in small, montane streams. Canadian Journal of Fisheries and Aquatic Sciences 53(6): 1403-1408.
- Young, M. K., R. B. Rader, and T. A. Belish. 1997. Influence of macroinvertebrate drift and light on the activity and movement of Colorado River cutthroat trout. Transactions of the American Fisheries Society 126: 428-437.
- Young, M.K., K.A. Meyer, D.J. Isaak, and R.A. Wilkison. 1998. Habitat selection and movement by individual cutthroat trout in the absence of competitors. Journal of Freshwater Ecology 13: 371-381.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Allendorf, F.W. and R.F. Leary. 1988. Conservation and distribution of genetic variation in a polytypic species, the cutthroat trout. Conservation Biology 2(2):170-184.
- Alowaifeer, A.M. 2019. The application of mass spectrometry in environmental chemistry: investigating biological cycling of arsenic, mercury and glycine betaine in aquatic ecosystems. Ph.D. Dissertation. Bozeman, MT: Montana State University. 167 p.
- Anderson, Ryen A. 2004. Occurrence and seasonal dynamics of the whirling disease parasite, Myxobolus cerebralis, in Montana spring creeks. M.Sc. Thesis. Bozeman, MT: Montana State University. 89 p.
- Bigelow, P.E. 1991. Evaluation of growth interruption as a means of mass-marking hatchery trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 93 p.
- Billman, H.G., C.G. Kruse, S. St-Hilaire, T.M. Koel, J.L. Arnold, and C.R. Peterson. 2012. Effects of rotenone on Columbia spotted frogs Rana luteiventris during field applications in lentic habitats of southwestern Montana. North American Journal of Fisheries Management 32(4):781-789.
- Brown, C.J.D. and J.E. Bailey. 1952. Time and pattern of scale formation in Yellowstone cutthroat trout Salmo clarkii lewisii. Transactions of the American Microscopical Society 71(2):120-124.
- Clothier, W.D. 1952. Fish loss and movement in irrigation diversions from the West Gallatin River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 32 p.
- Confluence Consulting Inc. 2010. Montana Department of Transportation Wetland Mitigation Monitoring Reports (various sites). MDT Helena, MT.
- Confluence Consulting Inc. 2011. Montana Department of Transportation Wetland Mitigation Monitoring Reports (various sites). MDT Helena, MT.
- Craig, V.E. 1952. A story of fish production as it applies to Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 92 p.
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- De Rito, J.N. Jr. 2004. Assessment of reproductive isolation between Yellowstone cutthroat trout and rainbow trout in the Yellowstone River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 60 p.
- Dillard, S.L. 2019. Restoring semi-arid lands with microtopography. M.Sc. Thesis. Bpzeman, MT: Montana State University. 97 p.
- Duncan, M.B. 2019. Distributions, abundances, and movements of small, nongame fishes in a large Great Plains river network. Ph.D. Dissertation. Bozeman, MT: Montana State University. 255 p.
- Dwyer, W.P. and R.G. White. 1995. Influence of electroshock on short-term growth of adult rainbow trout and juvenile Arctic grayling and cutthroat trout. North American Journal of Fisheries Management 15:148-151.
- Fausch, K.D. 1992. Life as a trout, predator. Trout Magazine Winter 1992. pp. 63-74
- Feldmeth, C.R. and C.H. Eriksen. 1978. A hypothesis to explain the distribution of native trout in a drainage of Montana's Big Hole River. Verh. Internat. Verein. Limnol. 20:2040-2044.
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- Gangloff, M.M. 1996. Winter habitat and distribution of Artic Grayling in Upper Red Rock Lake, Red Rock Lakes National Wildlife Refuge, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 101p.
- Gerald, J.W. 1965. Food habits of the Longnose Dace, Rhinichthys cataractae. M.Sc. Thesis. Bozeman, Montana: Montana State University. 27 p.
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- Gustafson, D. L. 1990. Ecology of aquatic insects in the Gallatin River drainage. Ph.D. Dissertation. Bozeman, MT: Montana State University. 194 p.
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- Heim, K.C. 2019. Mechanisms of Rainbow Trout hybridization with native Cutthroat Trout in the Lamar River of Yellowstone National Park. Ph.D. Dissertation. Bozeman, MT: Montana State University. 196 p.
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