BANFF NATIONAL PARK –
A white bucket sits in a creek flowing from Hidden Lake, a cold alpine lake behind Lake Louise Ski Resort in Banff National Park.
Inside the bucket, which has been transformed into a remote creekside incubator with some plumbing supplies, are dozens of tiny westslope cutthroat trout, an endangered species in Alberta.
“We have eggs that we put in the lake about three weeks ago,” Parks Canada aquatic specialist Shelley Humphries said Thursday as she gave reporters a first-hand look at the reintroduction of the species by Parks Canada in the backcountry lake.
“They’re almost fully mature and we’re about to release them back into the creek and lake in the next few days.”
The fish will join approximately 5,000 westslope cutthroat trout that were released at Hidden Lake as part of a restoration project that began in 2011.
“This is the first time in 50 years…there have been westslope cutthroat trout in this lake,” Humphries said.
Silver to yellow-green fish with red markings were once abundant at Hidden Lake, but were crowded out by non-native fish like brook trout after Parks Canada began stocking mountain lakes for anglers. the line – a practice that no longer takes place.
It took a decade for Humphries and his colleagues to begin bringing native fish back to the backcountry lake.
They first attempted to rid Hidden Lake of brook trout through angling, gill netting and electrofishing.
“It seemed like it was working at first, then after about four years we realized it was actually not working. We were still getting a lot of reproduction in the introduced brook trout, so we had to change the method. . “
They turned to a natural fish toxicant called rotenone to treat the lake in 2018 and again in 2019. Rotenone, which is derived from the roots of a plant, has been used around the world – including in national parks – to kill invasive fish.
“It breaks down very easily,” Humphries said, noting that it doesn’t harm birds or bears that eat the fish and can also be deactivated by introducing another compound.
They then monitored the lake to make sure the treatment was working and allowed the rest of the lake’s food web to recover before adding any westslope cutthroat trout.
But first they had to find some of the fish.
“They’re endangered, so you can’t just buy them,” Humphries said. “We had to find them in the landscape, we had to test them for the best genetics, which should give them the best chance of surviving climate change and other challenges ahead of them, and then we had to test them for make sure they didn’t have a disease.”
They worked with a hatchery to learn how to collect eggs and milt from fish in another mountain lake before they spawn. They were then raised for a time in the office, before being taken to the lake, put in makeshift incubators for a few weeks and released into the wild.
Megan Goudie, an ecosystems specialist, said she has worked on the project since she started at Parks Canada seven years ago.
“It’s like the pinnacle of our work here,” she said. “It’s really unbelievable.”
Humphries said Hidden Lake is an ideal location for the salvage project because a natural waterfall in the creek will prevent other fish from entering the lake.
“There’s going to be a safe haven here for the westslope cutthroat trout. It’s nice and cold, there’s still a few small glaciers in this valley and they’re going to be safe here on their own.”
Species at risk protection and aquatic restoration, she added, are two priorities for Parks Canada.
“We don’t let endangered species go without a fight,” Humphries said. “If there is a way to save them, we try to save them. We can do a great job for our trout. We still have amazing habitat.
“The cutthroat belongs here.”
This report from The Canadian Press was first published on September 3, 2022.