A species-at-risk fish is about to be reintroduced to its natural habitat in Banff National Park.
Parks Canada staff in the Lake Louise, Yoho, Kootenay field unit will add westslope cutthroat trout to Margaret Lake and other locations this spring.
The ongoing project will repopulate the fish species in some mountain lakes in Banff National Park after it was listed as threatened in 2013 under the federal Species at Risk Act.
“It’s about more than restoring just a single fish species. It’s about rebuilding the health of the entire ecosystem. … They’re an important link in the mountain food network,” said Brad Stitt, project manager for native fish restoration.
Stitt said once restored, it becomes a food source for grizzly bears and birds of prey.
Re-establishing the trout species to those waterbodies also acts as an indicator for Parks Canada in monitoring for “healthy, functioning ecosystems for all species, including humans.”
Other sites involving restoring westslope cutthroat trout that have been planned, completed or underway are Hidden Lake, Corral Creek, Helen Lake, Cascade Creek, Little Herbert Lake and Katherine Lake.
“We’re protecting areas for future generations and these protected areas play an important role in helping to create healthy, resilient ecosystems by restoring the species-at-risk,” Stitt said.
The work allows Parks Canada to turn back the clock to a time when westslope cutthroat trout were more common, more than a century ago.
Stitt said their historic range stretched from Bow Lake on the Icefields Parkway eastward to the Calgary area.
In the early 1900s, brook and rainbow trout, which aren’t native to the area’s waterbodies, were added to support demand for recreational fishing. They outcompeted westslope cutthroat trout for food.
Climate change and aquatic invasive species like whirling disease led to the range being reduced to less than 10 per cent of what it had been.
Westslope cutthroat trout eat bugs and other fish, which helps manage food supply in a waterbody to ensure one species doesn’t become more dominant than others.
“Restoring them on the landscape really makes westslope cutthroat trout more resilient in the mountain national parks, but also throughout their range,” Stitt said.
The federal agency identified key reintroduction habitats in 2018-19 and removed non-native fish before adding westslope cutthroat trout to mountain lakes.
About 2,000-3,000 brook trout were killed from 2022-24 to prepare for westslope cutthroat trout being returned to Margaret Lake. A natural fish toxicant called rotenone is used to remove them.
Once finished, Parks Canada monitors the areas.
Stitt said it’s a plan that’s had success in the U.S. and Canada.
Parks Canada is hopeful about the return of the westslope cutthroat trout to its lakes
Margaret Lake is a cold, freshwater waterbody near Hector Lake about 20 kilometres north of Lake Louise. Parks Canada has two options for reintroduction this spring.
It can move adult fish from other successful areas or set up a remote incubation site after they collect eggs and milt — sperm of male fish — then fertilize on-site, take them back to a mobile quarantine hatchery and incubate the eggs.
The latter is more labour intensive but has been “very successful” and minimizes risk, Stitt said.
“They both work well and we’re trying to decide which one would be best for Margaret right now,” he said.
François Masse, superintendent of the Lake Louise, Yoho, Kootenay field unit, said at the Banff annual planning forum in March the work being done is “very important” under Parks Canada’s mandate.
He noted the reintroduction is coming from local populations of westslope cutthroat trout and testing is done to ensure they’re healthy.
“It’s very exciting,” he said. “We’re bringing back the native species to the lakes of this place.”
Daniella Rubeling, acting superintendent of the Banff field unit, said at the forum it is a “significant accomplishment with long-term conservation benefits.”
The Banff and Lake Louise, Yoho, Kootenay field units are developing a draft 10-year multi-species list for “recovery, protection and monitoring species-at-risk in the park,” Rubeling said.
It will have 53 conservation recovery measures for 23 species and be made available later this year on the species-at-risk public registry.
“Healthy aquatic systems are really critical to the park’s overall ecological integrity,” Rubeling said.
