How Banff Saves the Westslope Cutthroat Trout

A western cutthroat trout is shown underwater in Banff National Park/John Jimmo, Parks Canada.

“Fish are difficult — they’re not as interesting as bears and bison and some of the rare birds we’re trying to save,” said Shelley Humphries, a Parks Canada water specialist. But he has a westslope cutthroat trout success story to tell in Banff National Park that he hopes people will listen to.

After more than a decade of hard work, Hidden Lake is finally a safe haven for the threatened but magnificent fish with a distinctive red cut and black spot on its lower jaw. Parks Canada placed thousands of eggs in remote streamside incubators at Hidden Lake and Fish Lakes in July — a milestone in the project.

He also completed a summer of guided conservation walks to showcase the project. “There’s a certain type of public visitor that wants this educational offering,” Humphries says. “They’re happy to go and walk around, but they have a lot of questions. I think the public needs good news too. We can save these fish. We just have to make a choice to save this fish.”

Listed under Population of Western Slope Alberta Species at Risk Act it is under threat because it occupies less than 10 percent of its historical territory.

The Parks Canada aquatics team installs remote streamside incubators at Banff/Kellen Martel, Parks Canada.

The fish lives in cold rivers and lakes and feeds on aquatic insect larvae. But throughout its range, it is also threatened by habitat loss, habitat damage and rising water temperatures caused by climate change.

Pure populations exist in some of Banff’s isolated streams, but most of the park’s fish are hybrids due to cross-breeding with introduced rainbow trout. This interbreeding dilutes the wild gene pool and makes the ferals less adaptable to change and less likely to survive in the long term.

This story actually starts with a big mistake. In the early 1900s, Parks Canada began stocking the mountain lakes of the country’s first national park with non-native species such as brook trout and rainbow trout to satisfy visitors who wanted to fish. It stopped the mismanaged practice in 1988, but these non-native species have flourished and their genes live on in the DNA of wild fish.

Banff anglers are no longer allowed to own jigs. And Parks Canada has spent years protecting and restoring the species by identifying safe habitat, removing non-native fish, reintroducing cutthroat trout on the western slope, and monitoring success.

Water specialist Shelley Humphries, center, and the Parks Canada team at Hidden Lake/Parks Canada in 2022

He conducted stream surveys to locate cutthroat trout on the west slope, collected DNA to determine whether they were hybrids or wild animals, and restored fish passage by repairing and replacing main culverts.

The serendipitous discovery of a waterfall downstream of uncharted glacier-fed Hidden Lake helped make the lake the perfect location for the conservation project. The waterfall prevents non-native trout from returning to the lake.

A Parks Canada team tried to remove the non-native species in 2011 by netting and electrofishing, but to no avail. In 2018 and 2019, Humphries introduced Rotenone, a natural fish toxin derived from plant roots and currently produced in the United States, based on advice from American colleagues. A pink powder is added to the water, where it is only toxic to fish (soon). shutting down their breathing) before breaking down.

“It’s a very safe chemical to use,” Humphries says. Subsequent monitoring of the stream showed that the food web had recovered.

A small western brook trout hatchling and still carrying the yolk/John Jimmo, Parks Canada

Once the secret lake is clear of any fish, it’s time to reposition the cutters. The team caught wild trout and transported the fertilized eggs to incubators. The eggs were then transferred to far-stream side incubators that protected them from predation.

The buckets cradle the growing trout and simulate the nesting environment as the water flows through the pipes and the valve is set up in the moving stream. Newly hatched Alewives with the yolk attached to their bellies swim in bucket-like containers for about a week until they absorb all the nutrients in the eggs and are ready to swim freely.

Guided conservation walks were held from July 10 to September 25, and sometimes people got to visit the buckets or get a rare chance to see the little fish.

“It’s very difficult to see fish in real life when they’re at this stage,” Humphries says. “So it’s been a lot of fun to show the public what these little fish look like.”

In 2022, Parks Canada offered protected hikes to Hidden Lake/Parks Canada.

The rides cost $73 (US$53) and lasted about six hours. They started with a shuttle ride that cut the 18 kilometer (11.1 mi) trail down to 10 kilometers (6.2 mi). Humphries hopes they can be offered again in 2023, adding that the fee does not fully cover the costs of providing guides and transport.

A restoration project is also underway in remote Margaret Lake and the Lake Catherine/Lake Helen area.

But as Humphries points out, anyone can hike to Hidden Lake along the scenic Skokie Trail.

As for the restoration project, there is funding until 2025, and for now the goal is to add fish to Secret Lake so they aren’t all the same age and spawn all at once.

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