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Montana Field Guide

Montana Field Guides

Rainbow Trout - Oncorhynchus mykiss

Native Species

Global Rank: G5
State Rank: S5

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General Description
The rainbow trout is Montana's number one game fish. Rainbow trout were introduced from numerous hatchery stocks into virtually every suitable habitat in the state, beginning in 1889. Scientists believe that only the rainbow trout of the upper Kootenai River drainage are native to this state. This small group of natives are a Fish of Special Concern. Rainbow trout introductions have caused a severe reduction in the range of the native cutthroat trout through hybridization and competition. Rainbow trout fare well under a wide range of habitat conditions from ponds to reservoirs, lakes, and streams. Various strains of rainbow trout, like breeds of cattle, are used for different purposes. The state has stocked hundreds of millions of rainbow in state waters in the last 100 years. However, today the policies have evolved and rainbow trout are stocked primarily in lakes and reservoirs but no longer in streams. The state record for rainbow trout is over 33 pounds, and fish of up to 10 pounds are common in some of our most productive waters. Rainbow are efficient at feeding on plankton, aquatic and terrestrial insects, and occasionally some smaller fishes. They spawn in early spring in running water, usually April or May, and maintain themselves quite nicely if the habitat is not degraded.

Diagnostic Characteristics
Montana: both pure and moderately hybridized populations of westslope cutthroat trout have a high incidence of basibranchial teeth, whereas pure rainbow trout lack these teeth; presence of basibranchial teeth in some individuals of a rainbow trout population indicates hybridization with westslope cutthroat trout (Leary et al. 1996). Individuals living in large or turbid lakes or under ice tend to be iridescent silver.

Species Range
Montana Range

All Ranges
Non-native
Native
(Click legend blocks to view individual ranges)
 


Observations in Montana Natural Heritage Program Database
Number of Observations: 14991

(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)



Migration
Migrates into tributary streams from lakes to spawn and river populations may also move upstream and/or into tributary streams.

Habitat
Cool clean streams, lakes, res., farm ponds. Able to withstand wider range of temperatures than most trout. Spawns in streams over gravel beds (Brown 1971, Holton 1981).

Food Habits
Feed mainly on aquatic insects but eat what is available to them. Large adults also eat fish (Brown 1971). River populations mostly insect eaters while zooplankton and forage fish are important in Lake Koocanusa (Huston et al. 1984).

Ecology
Populations of native and introduced rainbow trout as well as their hybrids coexist in Kootenai River drainage.

Reproductive Characteristics
Sexually mature 2-3 years but sometimes 1 year. Spawns April-July depending on water temperatures. Eggs hatch in 50 days at 50 degrees F. (Brown 1971). Young smolt at 0-2 years in tributaries and lake Koocanusa (Huston et al. 1984, May and Huston 1979).

References
  • Literature Cited AboveLegend:   View Online Publication
    • Brown, C.J.D. 1971. Fishes of Montana. Montana State University, Bozeman, MT. 207 pp.
    • Holton, G.D. 1981. Identification of Montana's most common game and sport fishes. Montana Outdoors reprint.
    • Huston J.E., P. Hamlin; B. May 1937-; Montana. Dept. of Fish, Wildlife, and Parks.; United States. Army. Corps of Engineers. Seattle District. 1984
    • Leary, R.F., W.R. Gould, and G.K. Sage. 1996. Success of basibranchial teeth in indicating pure populations of rainbow trout and failure to indicate pure populations of westslope cutthroat trout. North American Journal of Fisheries Management 16:210-213.
    • May, B.E. and J.E. Huston. 1979. Status of fish populations in the Kootenai River below Libby dam. Montana Department of Fish, Wildlife, and Parks. 57 pp.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Alvord, W. 1953. A study of scales from known-age trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 31 p.
    • Avery, E.L. 1969. Effects of domestic sewage on aquatic insects and salmonids of the East Gallatin River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 23 p.
    • Bahn, L. 2007. An assessment of losses of native fish to irrigation diversions on selected tributaries of the Bitterroot River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 118 p.
    • Bear, E.A. 2005. Effects of temperature on survival and growth of Westslope Cutthroat Trout and Rainbow Trout: implications for conservation and restoration. M.Sc. Thesis. Bozeman, MT: Montana State University. 68 p.
    • Belford, D.A. 1986. Abilities of trout to swim through highway culverts. M.Sc. Thesis. Bozeman, MT: Montana State University. 67 p.
    • Bianchi, D.R. 1963. The effect of sedimentation on egg survival of rainbow trout and cutthroat trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 28 p.
    • Bishop, C.G. 1953. Age, growth, and condition of trout in Prickley Pear Creek, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 22 p.
    • Boussu, M.F. 1953. Relationship between trout populations and cover on a small stream. M.Sc. Thesis. Bozeman, MT: Montana State University. 26 p.
    • Carty, D.G. 1985. Potential impacts of altering discharge pattern from Hauser Dam, Missouri River, on young-of-the-year brown and rainbow trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 84 p.
    • Clancey, T.P. 1983. Effects of renovation on the Sacajawea Park Lagoon system in Livingston, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 54 p.
    • 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.
    • Connor, W.P. 1988. Effects of gas supersaturated water on juvenile brown and rainbow trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 96 p.
    • Dalbey, S.R. 1994. Effects of electrofishing on long-term growth and mortality of wild rainbow trout. M.Sc. Thesis. Bozeman, MT: Montana State University. 46 p.
    • 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.
    • DosSantos, J.M. 1985. Comparative food habits and habitat selection of mountain whitefish and rainbow trout in the Kootenai River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 68 p.
    • Downing, D.C. 2000. Spawning and rearing ecology of Madison River rainbow trout in relation to whirling disease infection risk. M.Sc. Thesis. Bozeman, MT: Montana State University. 65 p.
    • Elser, A.A. 1967. Fish population of a trout stream in relation to major habitat zones and channel alterations. M.Sc. Thesis. Bozeman, MT: Montana State University. 27 p.
    • Fox, A.C. 1961. Parasite incidence in relation to size and condition of trout from two Montana lakes. M.Sc. Thesis. Bozeman, MT: Montana State University. 16 p.
    • Fredenberg, W.A. 1980. The fishery for fall-running rainbow trout in the Missouri River near Townsend, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 62 p.
    • Fry, J.P. 1960. The food of rainbow trout, brown trout and brook trout fry and fingerlings from five southwesternMontana streams. M.Sc. Thesis. Bozeman, MT: Montana State University. 37 p.
    • Ham, B.R. 2014. The evaluation of pellet type-preference and dietary soy sensitivity in Snake River cutthroat trout (Oncorhynchus clarkia). M. Sc. Thesis. Bozeman, MT: Montana State University. 77 p.
    • Hanna, T.D. 1992. The effect of oxygen supplementation on the toxicity of ammonia (nh3) in rainbow trout Oncorhynchus mykiss (Richardson). M.Sc. Thesis. Bozeman, MT: Montana State University. 51 p.
    • Hensler, M.E. 1987. A field evaluation of four strains of Salmo introduced into seven Montana waters. M.Sc. Thesis. Bozeman, MT: Montana State University. 61 p.
    • Hitchcock, R.W. 1988. Limitations to a rainbow trout population in north-central Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 131 p.
    • Holton, G.D. 1952. A trout population study on a small creek in Gallatin County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 46 p.
    • Javorsky, L.D. 1984. The trout fishery on a reach of the upper Yellowstone River, Montana, during 1982. M.Sc. Thesis. Bozeman, MT: Montana State University. 45 p.
    • Johnson, J. H. 1985. Comparative diets of Paiute sculpin, speckled dace, and subyearling steelhead trout in tributaries of the Clearwater River, Idaho. Northwest Sci. 59:1-9.
    • Johnson, R.L. 1962. The yield and standing crop of fish in Dailey Lake, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 25 p.
    • Kathrein, J.W. 1950. A partial fisheries survey of the Missouri River between Holter Dam and Cascade, Montana, with special emphasis on growth rate of trout and suckers. M.Sc. Thesis. Bozeman, MT: Montana State University. 27 p.
    • Kozakiewicz, V.J. 1979. The trout fishery of the lower Big Hole River, Montana, during 1977 and 1978. M.Sc. Thesis. Bozeman, MT: Montana State University. 74 p.
    • Kraft, M.E. 1968. The effects of controlled dewatering on a trout stream. M.Sc. Thesis. Bozeman, MT: Montana State University. 31 p.
    • Land & Water Consulting, Inc., Missoula, MT., 2002, Montana Dept. of Transportation Wetland Mitigation Monitoring Report, Year 2001: Big Spring Creek, Lewistown, Montana. Proj. No. 130091.029. July 2002. In 2001 Wetland Mitigation Monitoring Reports, Vol. I.
    • Land & Water Consulting, Inc., Missoula, MT., 2002, Montana Dept. of Transportation Wetland Mitigation Monitoring Report, Year 2002: Big Spring Creek, Lewistown, Montana. Proj. No. 130091.029. February 2003. In 2002 Wetland Mitigation Monitoring Reports, Vol. I.
    • Lere, M.E. 1982. The long term effectiveness of three types of stream improvement structures installed in Montana streams. M.Sc. Thesis. Bozeman, MT: Montana State University. 99 p.
    • Lund, J. A. 1974. The reproduction of salmonids in the inlets of Elk Lake, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 43 p.
    • Olenick, R.J., J.H. Gee. 1981. Tiger Salamanders (Ambystoma tigrinum) and stocked rainbow trout (Salmo gairdneri): potential competitors for food in Manitoba prairie pothole lakes. Canadian Field Naturalist 95(2): 129-132.
    • Venditti, D.A. 1994. Diet overlap and habitat utilization of Rainbow Trout and juvenile Walleye in Cooney Reservoir, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 90 p.
    • Zackheim, K. 1973. Exhibit H: Wildlife Study. In Ash Grove Cement Co. files.
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Rainbow Trout — Oncorhynchus mykiss.  Montana Field Guide.  .  Retrieved on , from