Parks Canada plans to reintroduce native fish extirpated from Banff National Park’s most manipulated and regulated river system back into their historic home next year.
Fisheries experts are hopeful all of the brook trout were removed from the lower Cascade River by the end of last month and now plan to assess how successful they’ve been.
So far 2,969 brook trout have been removed from the lower Cascade River since last November and the plan is to begin reintroducing westslope cutthroat trout in 2013 and 2014.
Parks Canada officials say they are working with TransAlta to try to get bigger flows into that river, which were reduced to a mere trickle compared to historical levels following construction of a dam at Lake Minnewanka in 1941.
They say increases in flows would create greater habitat diversity and improve fish habitat for various fish life stages, as well as the aquatic community as a whole.
“What we really need in that system is adequate flows to restore cutthroat populations,” said Charlie Pacas, an aquatics specialist for Banff National Park during a research conservation update May 24.
“This area has gone through an incredible amount of change since the dam was built in the 1940s.”
It is not yet clear how the Harper government’s big budget cuts are going to affect the various science and research programs across the country, including aquatics research.
But the plan for now is to make sure all brook trout have been eliminated from the lower Cascade system, from the Minnewanka dam to an area downstream of Cascade Ponds where the creek bed dries up.
Westslope cutthroat trout are listed as threatened in Alberta and nationally and are being considered for federal listing under the Species At Risk Act (SARA).
They have disappeared from almost 80 per cent of their historic North American range. Part of their range was the lower Cascade River in Banff National Park, a watercourse that has since been reduced to a tiny creek by the Lake Minnewanka dam.
In addition to this habitat alteration, brook trout were stocked for sport fishing.
Pacas said the brook trout are stronger competitors for food and habitat and, as a result, westslope cutthroat have been extirpated from the creek.
Historically, the Cascade circumvented Lake Minnewanka and drained an area of about 660-sq.km, with an annual average flow of about 8.0 cubic metres – about 15 per cent of the volume of the Bow River.
With the dam controlling flows into the Cascade, there is currently only 0.3 cubic metres flowing. The lower section from the power plant occasionally dries up and does not reach the Bow River, while the middle section below the dam almost never connects with the downstream section.
In fact, most people aren’t aware that the ditch that runs along the south side of the Trans-Canada Highway, beside the Legacy Trail, is part of the Cascade.