By Steve Hubrecht
Olive Lake in Kootenay National Park will be closed to the public later this year or at some point next year, as Parks Canada begins efforts to remove non-native fish species and then eventually reintroduce Westslope cutthroat trout.
As any local nature lover will tell you, westslope cutthroat trout are one of the Columbia Valley’s (and indeed one of the East Kootenay’s) most iconic native fish species, extremely popular with anglers. They are listed as ‘vulnerable’ in British Columbia and ‘threatened’ in Alberta. (They are also a ‘fish of special concern’ across the border in Montana, where they are also the designated state fish.)
Parks Canada will at the same time also remove non-native fish species, particularly brook trout, from two other remote lakes in Kootenay National Park — Talc Lake, near the three-way border between Kootenay National Park, Banff National Park and Assiniboine Provincial Park; and Kaufmann Lake, up Tokumm Creek, near the three-way border between Kootenay National Park, Banff National Park and Yoho National Park.
These two lakes, unlike Olive Lake, will not see westslope cutthroat introduced because westslope trout did not historically exist in these lakes (as they did in Olive), explained Parks Canada?Lake Louise, Yoho and Kootenay field unit aquatic ecologist?Shelley Humphries. But taking brook trout out of these lakes will still benefit westslope cutthroat, because the brook trout spill out of Talc and Kaufmann Lakes, affecting downstream population of westslope cutthroat trout.
“Essentially what we are doing is correcting mistakes Parks Canada made in the past with historic fish stocking,” Humphries told the Pioneer.
Parks Canada initially stocked Olive, Talc and Kaufmann Lakes with brook trout for anglers decades ago. Although Talc and Kaufmann Lakes may seem remote now, once upon a time they were on popular horse packing trails, and saw significantly higher numbers of visitors than they do today.
In the ensuing decades Parks Canada’s understanding of ecological science has evolved, and it’s now time to put things back the way they once were, outlined Humphries.
“We don’t understand all of the ecological complexities, but we know that when we have brook trout they do end up playing a different role in the ecosystem than westslope cutthroat trout or other native fish species such as bull trout or mountain whitefish,” she said. “We are confident that the species that have evolved to be there have a special place in the ecosystem.”
The efforts at Olive, Talc and Kauffman Lake follow on the heels of very similar projects in Banff National Park, which began in 2018.
“Those are going really well, they are almost done and we are looking to build on that success,” said Humphries.
The exact date when Parks Canada staff begin removing trout from Olive Lake is yet to be determined, but will be either later this year or next year, likely in September, outside of the tourist high season. Staff will use a fish toxicant — rotenone — to kill the brook trout in Olive Lake, then they’ll pick up the fish, and clean up the lake.
They’ll need to do it twice to make sure they get all the brook trout. “They can be tricky and sometimes difficult to remove,” said Humphries. “If they have already spawned, their eggs will not be affected by the toxicant.”
They will then use an auger-like machine called a hopper to de-activate the rotenone before it leaves Swede Creek (Olive Lake’s outlet creek) and enters the Kootenay River. After that they’ll double check Olive Lake and Swede Creek to make sure zooplankton and invertebrate populations are recovering (the introduced westslope cutthroat will need these food species to survive).
To restock Olive Lake, Parks Canada staff will catch some of the most genetically diverse westslope cutthroat in Banff National Park. They will take the eggs from the females and the ‘milk’ (reproductive cells) from the males. They’ll fertilize the eggs, put them in incubators in Parks Canada offices and then, once the eggs are eyed, they will place them in Olive Lake.
“Then they’ll hatch and swim away,” explained Humphries.
But she cautioned that part of the process is at least several years away, since removing the brook trout can take some time.
The process at Talc Lake and Kauffman Lake will be similar, except everything needs to be flown in by helicopter, given the remoteness of those lakes.
Once the work at Olive Lake begins, it will offer a great spot to see Parks Canada conservation work in action, since it is literally at the side of Highway 93 South, outlined Humphries.
In the meantime, those who can’t wait can get a glimpse of the westslope cutthroat re-introduction project in Banff National Park, through Parks Canada’s guided interpretive hike to Hidden Lake, behind Lake Louise. But be warned, you need to go soon; when the project finishes, so will the guided hikes.
“The interpreters are excellent, and we do get great feedback,’ said Humphries, who has also led field trips to the Hidden Lake reintroduction project as part of the Columbia Valley-based Wings Over the Rockies Festival.
“There are always a lot of questions, and participants usually leave very positive,” she said. “I think there is a lot of interest in this kind of conservation work, and it is a great, uplifting story. A lot of conservation stories have a negative tone, but this is a success story. We can save these fish.”