YOHO – In an unprecedented move, Parks Canada has shut down all waterbodies and shorelines in Yoho and Kootenay national parks after whirling disease – a deadly disease known to kill off fish populations – was detected in more regions.
After discovering whirling disease in Yoho’s Emerald Lake last month, Parks Canada officials say further sampling and preliminary test results found suspected cases of the disease in the Kicking Horse River, Wapta Lake, Finn Creek, Monarch Creek and confluence of Emerald River and Kicking Horse River.
“As a result, Parks Canada has taken quick and decisive action to protect fish populations in Yoho and Kootenay national parks,” said Justin Brisbane, aquatic invasive species regional communications officer for the mountain national parks in a statement.
“All waterbodies and shorelines in Yoho and Kootenay national parks are closed until March 31, 2024, effective Thursday, Oct. 26, 2023.”
On Sept. 20, whirling disease was discovered in Emerald Lake – the first case in Yoho National Park but also in all of the province of British Columbia.
Until then, whirling disease had been contained to neighbouring Banff National Park and Alberta provincial lands after its initial discovery in Canada in 2016 – in Banff’s Johnson Lake.
A PCR test confirmed the disease in non-native brook trout in Emerald Lake, about 11 kilometres northwest of Field.
At that time, Parks Canada quickly shut down Emerald Lake to fishing, swimming, paddling, and boating on the weekend to prevent further spread of the disease, although designated trails around the lake remain open.
“Aquatic invasive species pose a significant threat to the health of national parks and vital aquatic ecosystems,” said Brisbane.
“These species disrupt and irreversibly damage aquatic ecosystems, affecting vulnerable species at risk. They can also spread downstream beyond park boundaries through interconnected river systems.”
Named for the circular swimming patterns of infected fish, whirling disease can affect several fish species, including bull trout and westslope cutthroat trout as well as rainbow trout, mountain whitefish, brown and brook trout.
Whirling disease is not spread directly between fish, but a parasite is spread through contact between fish and a freshwater worm.
Once the parasites have invaded the cartilage of the fish, it can result in deformities in the jaws, head, gill cover, and body, and can also cause the tails of infected fish to turn black. It can also impair the nervous tissue, resulting in the characteristic whirling swimming behaviour.
After the deadly disease was discovered in Banff’s Johnson Lake in 2016, the small lake near the Banff townsite was drained and all fish were killed. The main concern was it would cause harm to at-risk species like bull trout and westslope cutthroat trout.
Thought to have been introduced from Europe, whirling disease was first detected in the United States in 1958. It became a major concern in the 1990s when losses of up to 90 per cent of the wild rainbow trout in several streams in Colorado and Montana were attributed to whirling disease.
According to the closure notices for Yoho and Kootenay national parks, all in-water and shoreline activities are prohibited and it is against the law to approach remain at a river, creek or lake to within three metres.
Banned shoreline activities include but are not limited to hiking, walking or cycling.
Prohibited water activities include but are not limited to fishing, swimming, diving, wading and the use of any watercraft such as a boat, paddle board, raft, or any other vessel.
The following exceptions apply – crossing a lake or river on approved trails, bridges, and fords; collecting treatable water for the purposes of drinking; crossing a frozen waterbody or shoreline.
Use of rental canoes at Emerald Lake is permitted.
