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Did You Know? - Wild Trout

Home Montana's Wild Trout
Montana's Wild Trout

Wild trout are what makes Montana so unique. The state has managed all trout fisheries as "wild" since the 1970's, meaning that all trout populations here are self-sustaining, relying on high-quality habitat for spawning, shelter and food.

All life stages of Montana's trout depend on habitat, which is why maintenance, improvement and protection of habitat is so important.

On these pages you can learn about all of Montana's wild trout - native, introduced and hybrids.


Montana's Native Trout

All populations of Montana's native trout species (except mountain whitefish, which are so numerous that their limit is 50 per day in some places) face risks of long-term survival due to human-caused impacts on habitat, including the worst threat of all - looming extreme climate change. Also, for many years, native species were constantly deluged with plantings of introduced species by the state and others.

Today, however, the plight of Montana's native trout is a priority issue, and the shared hope is that enough quality habitat can be maintained to ensure the survival of these populations.

Not surprisingly, fishing for these species is generally either limit-restricted, catch-and-release or, in the case of bull trout, totally illegal.


Species Information

Illustrations Courtesy of Joseph Tomelleri


Maps show Species Distribution in Montana

Bull Trout - Salvelinus confluentus
Bull trout are actually a char (as are brook trout and lake trout), and are found in the Clark Fork and Flathead drainages of western Montana. The bull trout's rapidly declining population trend has led to their designation as a Threatened species due to a variety of human-caused habitat impacts. Adult bull trout are large, predatory fish that are vulnerable to capture, a fact not lost on many western Montana fishermen. However, because the bull trout is severely imperiled and is a federally listed "Threatened" species, any harassment or capture is illegal, including holding caught fish  for photographs for time lengths beyond a few seconds and entrainment in irrigation systems (though both practices are freely tolerated by authorities).

Bull trout are a sensitive species that do not tolerate high sediment levels in their spawning streams, and require water temperatures below 15 degrees C (60 degrees F).

Bull trout have two forms: stream-adapted (fluvial) and lake-adapted (adfluvial). Some fluvial bull trout populations reside and spawn in smalller streams their entire lives, while fluvial bull trout residing in larger streams and rivers migrate into smaller tributary streams to spawn. Adfluvial bull trout residing in lakes also migrate into tributaries to spawn.

Bull trout have been displaced in many areas through competitive interaction with introduced brook trout. Bull trout and brook trout also interbreed, which further decreases bull trout populations. Introduced lake trout feed voraciously on both young bull trout and bull trout prey species, although, strangely, Montana Fish, Wildlfe and Parks steadfastedly maintains lake trout fisheries in the top strongholds for bull trout in Montana. The bull trout may be considered the grizzly bear of the fish world in relationship to its need for unaltered habitat. Climate change may claim the bull trout as the first native trout species in Montana to go extinct due to rising stream temperatures and related loss of viable habitat for an already badly fragmented population.

Westslope Cutthroat - Oncorhynchus clarkii lewisi

Cutthroat trout are so named for the red slashes near the lower jaws.

The westslope cutthroat's historical range was all of Montana west of the Continental Divide as well as the upper Missouri River drainage. This fish has been seriously reduced in its range by two primary factors: hybridization with rainbows and/or planted Yellowstone cutthroats, and human-caused habitat degradation and loss. The MFWP and other agencies have long considered westslope cutthroat populations somewhat healthy, but only because any fish looking like a westslope cutthroat is usually considered to be one, even though genetically pure populations are thought to occupy only 2 to 4 percent of all historical range, with the others hybridized to various degrees. Also, stocked fish often come from a narrow genetic base, and are often thus inferior to true natives with much broader genetic heritage.

Spawning and rearing streams tend to be cold and nutrient poor. Westslope cutthroat trout seek out gravel substrate in riffles and pool crests for spawning habitat.

Management of this species involves protecting the population strongholds and making tough decisions on restoration priorities for the depressed populations. The State of Montana has altered fishing regulations to reduce fishing mortality. Montana has also developed a Conservation Agreement signed by nine government agencies and conservation groups.

West Slope Cutthroat

West slope cutthroat mapping

Yellowstone Cutthroat - Oncorhynchus clarkii bouvieri

The Yellowstone cutthroat trout is one of two cutthroat trout subspecies in Montana. They have a golden coloration and larger spots more widely distributed on their sides than the westslope cutthroat trout. The Yellowstone cutthroat, as the name implies, is native to the Yellowstone River drainage of southwest and south-central Montana. Like the westslope cutthroat, this fish readily interbreeds with rainbow trout. Genetically pure fluvial (stream and river) populations occupy less than 10 percent of historical range. Yellowstone cutthroats are (because of more restricted range) more threatened than westslope cutthroats.

Yellowstone 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.

Yellowstone cutthroat are also 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 de-water 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 Yellowstone cutthroat broodstock, though questions of narrow genetic heritage also haunt this source of stocked trout.

Yellowstone Cutthroat

Yellowstone Cutthroat Map

Columbia Basin Redband Trout - Oncorhynchus mykiss gairdneri

This extraordinary fish is Montana's only native form of the non-native and commonly-encountered (due to extensive stocking) rainbow trout. The redband trout is found in just a few isolated populations in the Kootenai River drainage of NW Montana. The redband trout prefers low-gradient, mid-elevation reaches with an abundance of complex pools. Genetically pure redband trout are thought to occupy less than a third of their small historic range.

Klamath Redband Trout

Montana Artic Grayling - Thymallus arcticus montanus

The Arctic grayling is a species native to northern North America. The only populations native to the lower 48 states were in Michigan and Montana, and the Michigan population is now extinct. Consequently, the fluvial or river-dwelling population in the upper Big Hole River are the last remnants of this native Fish of Special Concern. Originally, the fluvial Arctic grayling was widespread throughout the upper Missouri river drainage as far downstream as Great Falls. Lewis and Clark made note of these "new kind of white or silvery trout" in 1805.

Today in Montana Arctic grayling are found primarily small, cold, clear lakes with tributaries suitable for spawning. They do not coexist well with other fishes except cutthroat trout and others with which they evolved.

Although fluvial Arctic grayling inhabit the entire Big Hole River, highest densities occur in the vicinity of Wisdom. The majority of spawning occurs near Wisdom in the main stem and several tributaries.

Montana Artic Grayling

Montana Artic Grayling map

Mountain Whitefish - Prosopium williamsoni

The mountain whitefish is familiar to most Montanans. This widespread native fish is primarily a stream-dwelling species, but populations are also found in reservoirs and lakes. The mountain whitefish is found in abundance in most clear, cold rivers in the western drainages and eastern mountain front of Montana.

Whitefish provide forage for larger trout. They have evolved with our native trout and have been shown to provide little competition with trout. Their pointed snout and small round mouth makes them efficient at vacuuming invertebrates from the substrate while trout tend to feed more on drifting insects. Mountain whitefish often congregate in large schools on their fall-spawning runs to broadcast their adhesive eggs over gravel bars in tributary streams.

Montana Whitefish

Montana Whitefish map

Species information and distribution maps courtesy of Montana Fish, Wildlife and Parks