B.C. anglers and boaters will have to avoid Yoho and Kootenay national parks for another year after the continued persistence of an aquatic invasive species.
Parks Canada has announced that it is extending the closure of all waterbodies in both parks until March 31, 2026 due to whirling disease. Highly infectious, whirling disease is found in finfish, including trout, salmon, and whitefish, and is spread through an invasive parasite known as Myxobolus cerebralis.
The waterbody closure only applies to anglers and watercraft, including kayaks, paddleboards, canoes, and inflatable boats. This is because they pose the most risk of transferring the disease to other waterbodies. The parks will be open to swimming and shoreline activities as the disease is not harmful to humans or pets. Visitors are welcome to use swimming aids, such as water wings, lifejackets, and wet suits, as well as beach toys.
Anyone who violates the waterbody closure with angling equipment or a watercraft could face a $25,000 fine under the Canada National Parks Act.
The government agency first closed the parks’ waterbodies in October 2023 after a suspected case of whirling disease was spotted in Yoho National Park’s Emerald Lake. Testing by the Canadian Food Inspection Agency confirmed the disease in December 2023.
In December 2024, three trout samples were found to be infected with the disease in Kootenay Lake. Park staff are unclear as to whether the disease was transferred from Yoho.
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.
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Once established, whirling disease can be extremely difficult to get rid of as there’s no known cure. As a result, it’s incredibly damaging to fish populations. The disease spreads when the invasive freshwater parasite settles in the soil of a waterbody. Tubifex worms 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. The parasite can live in the waterbed for 20 years, thriving in waters between 10 to 15 degrees Celsius.
Rainbow, steelhead, and cutthroat trout as well as sockeye and kokanee salmon are the most susceptible species to the disease. Of them, it tends to infect juvenile fish first. This is because their cartilage has yet to harden, making it easier for the spores to attach. When a waterbody reaches severe levels of whirling disease, overall deaths of infected young fish can reach 90 per cent.
The disease is known to cause deformed heads, bent spines, dark tails, and bulging eyes. It also causes fishes’ brains to only communicate with one side of their bodies. Infected fish can be identified by the abnormal whirling pattern they swim in—hence the name.
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 encountered the parasite in an infected area. The U.S. has been grappling with whirling disease since the 1950s. Montana and Colorado saw some populations of rainbow trout decline by 90 per cent after the disease was introduced.
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. In a May 2024 meeting, Shelley Humphries, a Parks Canada aquatic specialist for Lake Louise, Yoho, and Kootenay, told the Invasive Species Council of B.C. that park staff were in a containment response phase.
This involves extensive testing. In 2023, staff collected 90 fish from Yoho and Kootenay. Their goal in 2024 was to collect closer to 150 to 175 to get a better sense of the disease’s prevalence.
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Staff were also using sentinel cages on the Kootenay River. These are cylindrical cages filled with hatchery-born rainbow trout. Staff would test the trout every few weeks to see whether they had contracted the disease.
Park staff are also promoting preventative measures among visitors. This includes the clean, drain, and dry initiative. Cleaning means removing all mud, sand, and plant materials from your watercraft, trailer, or any other equipment before launching it into another waterbody.
After being in the water, watercrafts and other equipment must be drained on dry land. This includes coolers, buckets, and other compartments that may contain water. As of May 17, 2024, it is illegal to transport a watercraft in B.C. with the drain plug still in.
Finally, watercraft and equipment should be dry before entering a new body of water. For all mountain national parks, Parks Canada has mandated that equipment and watercraft used in Alberta, B.C., or the territories must be dried for 48 hours before entering another waterbody. If the equipment or watercraft was used outside of those areas, it must be dried for 30 days.
“We are getting people that are being willfully non-compliant, and we can’t have that,” said Humphries.
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