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Montana Animal Field Guide

Montana Field Guides

Columbia River Redband Trout - Oncorhynchus mykiss gairdneri
Other Names:  Interior Redband

Species of Concern

Global Rank: G5T4
State Rank: S1

Agency Status


External Links

General Description
Columbia River Redband Trout are a native trout of western North America. There is considerable variation in the life history in this group of trout. Resident stream populations are found throughout the Columbia River basin. A lake variation known as Kamloops are found in some larger lakes in the Columbia and Frasier River (British Columbia) basins. A third variation is the steelhead that migrated from the ocean as far as the upper Snake River, Idaho (almost 1000 miles) (Behnke 1992).

Diagnostic Characteristics
Characteristics vary considerably among populations of Montana's stream-resident Columbia River Redband Trout, but generally they can be differentiated from the non-native Coastal Rainbow Trout by larger more rounded spots, parr marks that tend to remain into adulthood and are more orange-red around the lateral line surrounded by greenish-yellow, rather than pink-red around the lateral line surrounded by dark green and silver like Coastal Rainbow Trout. Columbia River Redband Trout also have very distinct white tips on the anal, dorsal and pectoral fins.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.

Western Hemisphere Range


Summary of Observations Submitted for Montana
Number of Observations: 47

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Columbia River Redband Trout are typically a stream-resident fish that make short spawning migrations either in the same stream or often into smaller tributaries.

Columbia River Redband Trout prefer cool, clean, relatively low gradient streams but, in some circumstances, are able to withstand wider temperature variations than their cousins the Westslope Cutthroat Trout.

Food Habits
Interior Columbia River Redband Trout feed mainly on aquatic insects but eat what is available to them. Large adults also eat fish. River populations are mostly insect eaters, while zooplankton and forage fish are important in Lake Koocanusa.

Populations of native Columbia River Redband Trout, Westslope Cutthroat Trout and introduced Coastal Rainbow Trout coexist in the Kootenai River drainage. Interestingly, Columbia River Redband Trout have hybridized with Westslope Cutthroat Trout in some drainages and these crosses are considered to be naturally occurring and historic. Hybridization between Columbia River Redband Trout and Coastal Rainbow Trout, on the other hand, is considered to be a danger to the continued existence of Columbia River Redband Trout.

Reproductive Characteristics
Columbia River Redband Trout reach sexual maturity in 2 to 3 years. They spawn from late April through mid-June, depending on water temperatures. The fry typically emerge from the gravel in mid-July.

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Citation for data on this website:
Columbia River Redband Trout — Oncorhynchus mykiss gairdneri.  Montana Field Guide.  .  Retrieved on , from