Enthusiasts of Yoho and Kootenay National Parks will have to find a different spot to enjoy the water this summer. Parks Canada announced that all waterways in the two B.C. national parks will be closed to the public until at least March 2025 due to the detection of whirling disease.
First detected in B.C. in late 2023, whirling disease is found in finfish, including trout, salmon, and whitefish, and is spread through an invasive parasite known as myxobolus cerebralis.
So far, the disease has been identified in B.C.’s Emerald Lake, Kicking Horse River, Wapta Lake, Finn Creek, and Monarch Creek.
The waterway closure means members of the public will no longer be allowed to fish, swim, boat, or participate in any other recreational water activities in Yoho and Kootenay. The ban also extends to shoreside activities with Parks Canada asking walkers and cyclists to remain at least three metres away from all shorelines.
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Parks Canada has also stepped up measures in Alberta’s Waterton Lakes National Park, prohibiting all personal aquatic equipment, such as waders, fishing gear, snorkels, and life jackets, as well as all personal watercraft. Bringing external equipment into the park can contribute to the spread of whirling disease.
Canada’s first known case of whirling disease was identified in Banff National Park’s Johnson Lake in August 2016. Over the next two years, Alberta identified cases in the Bow River watershed, Oldman River watershed, Red Deer River watershed, and North Saskatchewan River watershed.
Once established, whirling disease can be extremely difficult to get rid of. While officials are unsure of how the disease was first introduced into Canadian waters, its speculated that it was transferred from boating, fishing, or wading equipment that came into contact with the parasite in an infected area.
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The disease, which causes deformed heads, bent spines, dark tails, and bulging eyes, can be identified in infected fish by the abnormal whirling pattern they swim in. This is because the fish’s brain is only able to communicate with one side of its body. The disease spreads when the parasite settles in the soil of a waterbody. Tubifex worms then eat the parasite, producing triactinomyxon spores that attach themselves to nearby fish infecting them through their skin. The disease typically leads to the fish’s premature death, which once again releases the parasite back into the water starting the cycle again.
While the disease isn’t harmful to humans or other mammals, it can live in the waterbed for 20 years, thriving in waters between 10 to 15 degrees Celsius. Young fish are particularly susceptible. According to the Canadian Food Inspection Agency (CFIA), overall deaths of infected young fish can reach 90 per cent.
While whirling disease may be relatively new to Canada, the U.S. has been grappling with it since the 1950s. Montana and Colorado saw some populations of rainbow trout decline by 90 per cent after the disease was introduced.
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In previous instances, some researchers have removed and killed infected fish to try and eradicate the disease from the waterbody, but this can impact the surrounding ecosystem. Primarily, officials practice preventive measures to try and keep the disease from spreading. This includes the clean, drain, and dry initiative: Clean and inspect any watercraft, trailer, or equipment that has come into contact with water or fish; drain the water from your watercraft and equipment on dry land; let your watercraft or equipment air dry for 24 hours before entering a new body of water.
CFIA also advises washing and disinfecting any clothing or footwear worn in the water. “Although whirling disease has been found in parts of Alberta and British Columbia, it is still very important to follow the measures above even in infected areas to prevent further spread between waterbodies,” CFIA said in a statement. “This is because not every susceptible finfish population in an infected area has whirling disease and these measures also help keep the level of the parasite low to reduce the impact on finfish.”
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