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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
* (see State Rank Reason below)

Agency Status
USFWS:
USFS: SENSITIVE
BLM:
FWP SWAP: SGCN1


 

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State Rank Reason (see State Rank above)
The Columbia River Redband trout is currently ranked "S1" in Montana because it is at extremely high risk of extirpation in the state due to very limited and/or rapidly declining population numbers, range and/or habitat.
 
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

 


Range Comments
The Columbia River redband trout (Oncorhynchus mykiss gairdneri) is native to the Fraser and Columbia River drainages east of the Cascade Mountains upstream to barrier falls on the Pend Oreille, Spokane, Snake and Kootenai rivers in Idaho, Oregon, Washington and Montana.

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

Recency

 

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



Migration
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.

Habitat
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 insectivores, while zooplankton and forage fish are important food sources in Lake Koocanusa.

Ecology
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.

Management
Long-term conservation and management of this subspecies will require state and federal agencies to develop a comprehensive plan to protect and restore redband trout throughout their native range in Montana. One objective should be to develop a wild brood stock for reintroductions throughout the Kootenai River drainage.

Threats or Limiting Factors
Land and water use practices, habitat loss, over harvest, hybridization and a geographical restricted range are leading factors contributing to the decline of redband trout abundance, distribution and genetic diversity in the Columbia River basin (Williams et al. 1989; Behnke 1992).

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