Parks Canada officials say they're closely watching lakes and rivers in Kootenay and Yoho national parks for a parasite that could "decimate" as much as 90 per cent of young trout and salmon.
The first suspected case of the disease in British Columbia was found in September in Emerald Lake, in Yoho National Park, prompting the closure of the lake and other nearby waterways.
Francois Masse, Parks Canada’s field unit superintendent for Lake Louise, Yoho and Kootenay national parks, says they later found “additional suspected cases” of the disease in the Kicking Horse River, Wapta Lake, Finn Creek, and Monarch Creek.
Parks Canada has closed all waterbodies in Yoho and Kootenay national parks until the end of March next year.
Masse says it's too early to say what other measures they might take to stop the spread, but the public is asked to respect all closures.
Whirling disease doesn't pose a risk to humans, but can be deadly for trout, salmon and whitefish, causing spinal deformities and fish to swim in erratic circles.