Paddlers, anglers, and beachgoers need to carefully check water activity restrictions before heading out on Banff National Park’s waterways this year. Whirling disease, a fish disease caused by an invasive parasite, has been detected in Lake Louise, prompting Parks Canada to announce new restrictions for water-based recreational activities to prevent the disease’s spread.
Paddling activities, large inflatables, and the use of waders or wading boots by anglers, are now banned at Lake Minnewanka, Bow Lake, and Moraine Lake. Lake Louise will continue to allow water-based recreational activities, but visitors must follow Clean, Drain, Dry procedures.
Whirling disease causes neurological damage to fish such as trout and salmon. The disease has no cure and a fatality rate of up to 90 per cent. Its symptoms include deformities and a “whirling” swimming behaviour in sick fish.
The parasite that causes whirling disease belongs to the same broad group as jellyfish. Because of its unique life cycle, it’s a tricky parasite to manage, says Viraj Rajendra Muthye, the founder of the Creative Science Alliance. Muthye studied the genome of the group the parasite belongs to—called myxozoans—during his graduate studies.
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The parasite easily spreads during its spore stage. The spores can attach to mud, shoes, boat hulls, clothing, and other gear, says Muthye. “If you visit one river and then go to another without properly cleaning your equipment, you could unintentionally move those spores.”
Adding to the difficulty of tackling this disease, the parasite infects different hosts to complete its life cycle. “It lives partly in tubifex worms and partly in fish,” says Muthye. “So you’re not just dealing with free-floating spores in the water, you’re dealing with multiple life stages across different hosts.”
Muthye says that the most important thing to remember about the disease is that it does not infect humans. He stresses the importance of education about the disease. “Parks Canada is doing a very good job—and I am trying to do the same—of raising awareness about this disease.” Parks Canada and Government of Alberta have excellent online resources on the disease and Clean, Drain Dry procedures, he adds.
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