Westslope cutthroat trout

Banff National Park

Quick facts

Identified by the red slash on its lower jaw
Grows up to 50 cm
Eats aquatic insect larvae
Lives in cold streams and lakes

Federal Status:
Threatened in A.B.

Once native to the montane and foothill streams of southern Alberta (within the Oldman and Bow watersheds) , westslope cutthroat trout populations are declining across their historical range

Although westslope cutthroat trout can still be found in Banff National Park in isolated bodies of water and streams flowing into the Bow River, historic non-native fish stocking practices have resulted in crossbreeding with non-native rainbow trout and the creation of hybrid fish populations. We no longer stock non-native fish in Banff National Park and luckily, a few genetically pure populations of westslope cutthroat trout still exist.

Parks Canada is working to protect westslope cutthroat trout and restore critical species habitat.


Note to anglers – to reduce the spread of aquatic invasive species such as Whirling Disease:

  • Ban on felt-soled wading boots - as they are difficult to clean
  • Zero possession limit for all fish to eliminate movements of fish dead or alive (except for Lake Trout from Lake Minnewanka reservoir).
  • Clean. Drain. Dry is a best practice

Fishing Regulations Summary (PDF 787 KB)


Why are westslope cutthroat trout in danger?

Across their range, westslope cutthroat trout are threatened by:

  • Displacement, competition and hybridization with non-native fish
  • Increasing water temperatures due to climate change
  • Threat of disease such as whirling disease

Genetic invaders

So the rainbows mix it up with the cutthroats – what’s the problem? Crossbreeding dilutes the wild gene pool and makes westslope cutthroat less adaptable to changes.

Co-habitat challenges

Sharing habitat with other trout species can also be a challenge for westslope cutthroat trout. Brook trout can outcompete westslope cutthroat trout because they have broader habitat tolerances and hatch earlier in the season. For example, brook trout can thrive across a range of water temperatures whereas westslope cutthroat trout have specific preferences. This gives brook trout a competitive advantage because they are not as picky about where they live.

What are we doing to help this species?

  • Conducting stream surveys to locate westslope cutthroat trout in the park
  • Collecting DNA from westslope cutthroat trout to find out if they are hybrids or wild
  • Restoring fish passages by fixing and replacing highway culverts
  • Determining historic distribution levels and range to direct future restoration projects
  • Exploring restoration strategies to increase westslope cutthroat trout populations with high quality genetics
  • Creating programs to stop the spread of aquatic invasive species by promoting best practices such as Clean Drain Dry

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