Rainbow lake: The flight for conservation

Banff National Park

After five years of hard work aimed at preserving one of Banff National Park’s native fish species, the last batch of Westslope Cutthroat trout were flown by helicopter from Sawback Lake to Rainbow Lake. The team of people responsible — including Parks Canada staff, volunteers and private contractors — collectively cheered as the helicopter-bucket lifted from the water with its precious cargo in the summer of 2015. This was the final step in a conservation project to help restore Westslope Cutthroat trout populations in part of the Upper Cascade watershed in Banff National Park.

Westslope Cutthroat trout are a threatened species and Banff National Park is home to some of the last remaining genetically pure populations. Once found throughout the Pacific Northwest, including Montana, Oregon, British Columbia and Alberta, Westslope Cutthroat trout have disappeared from over 90% of their historic range. A key threat for Westslope Cutthrout trout in Banff is interbreeding with Rainbow trout, a non-native species in the park, resulting in a hybrid species. Rainbow trout were introduced to the park many years ago and stocked in places like Rainbow Lake in the Upper Cascade watershed to provide enhanced sport fishing opportunities for visitors.

What is Parks Canada doing to help?

In order to restore a genetically pure population of Westslope Cutthroat trout in the Upper Cascade watershed, the non-native Rainbow trout needed to be removed, along with any hybridized trout. In 2011, Parks Canada started this removal process taking away any fish that were easily identified as Rainbow Trout in Rainbow Lake, Rainbow Creek and Sawback Creek. The remaining fish in the stream sections, were tagged and genetic testing was conducted to identify pure Westslope Cutthroat trout. Those determined to be Rainbow trout or hybrids were removed, leaving only primarily pure Westslope cutthroat trout.


Once this was done, one hundred Westslope cutthroat trout were caught from Sawback Lake in 2015 over two days and flown by helicopter to be introduced into nearby Rainbow Lake in the hope that they would eventually move downstream into Sawback Creek and the Upper Cascade River. This downstream trickle of genetically pure Westslope Cutthroat Trout would overtake any remaining hybrids and reinforce genetic purity of Westslope Cutthroat trout in the entire Cascade River watershed.

Restoring Banff’s Westslope Cutthroat trout population

Several years later, the native westslope cutthroat trout in Rainbow Lake are thriving. The success of this project has not only created a bigger and healthier population of Westslope Cutthroat trout, but it means that Sawback Creek will now qualify as a new core population . This means we have restored pure Westslope Cutthroat trout to their native waters.

Today, Parks Canada continues working to protect and restore populations of Westslope Cutthroat trout throughout Banff National Park and prevent the introduction and spread of aquatic invasive species.

How you can help Banff’s aquatic communities:

  • A valid national park pass is required by anyone fishing in the parks. For information on park passes, visit a Parks Canada information centre.
  • Prevent the spread of invasive species - Clean, drain and dry watercraft and gear.
  • Use water responsibly– wherever you are!
  • Do not pollute – whether you are at home or visiting the park.
  • Join volunteer opportunities within the national park.

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