Water users throughout the Columbia River watershed are being urged to take additional precautions to prevent the spread of whirling disease, an aquatic parasite that can cause serious harm to trout, salmon and whitefish populations.
Whirling disease was first detected in British Columbia in December 2023 in the Columbia River watershed. With no treatment currently available, the Columbia Shuswap Invasive Species Society says containing the parasite and preventing it from reaching additional waterways is critical.
The disease is caused by Myxobolus cerebralis, a microscopic parasite that primarily affects juvenile fish in the salmon family. It can damage the brain stem and spinal cord, causing physical deformities and the distinctive circular swimming behaviour that gives the disease its name.
Infected fish may also develop a darkened or black tail. In severe cases, the disease can cause significant mortality within affected fish populations.
Whirling disease does not pose a health risk to people or pets. Eating an infected fish or swimming in water where the parasite is present is not considered harmful.
However, the parasite can be moved from one waterbody to another through infected fish, fish parts, mud, sediment, watercraft and recreational equipment.
People should never move fish or fish parts between waterbodies. Fish remains should be disposed of at designated fish-cleaning stations or through local solid-waste systems, rather than being placed in the water or washed down a drain.
Boaters, anglers and other water users are also being reminded to “Clean, Drain, Dry” their watercraft and equipment before travelling between waterways.
Boats, trailers, waders, lifejackets, water toys and other gear should be cleaned of all mud, plants and debris. Water should be drained from tanks and compartments while on land, and equipment should be allowed to dry completely for at least 24 hours before entering another waterbody.
Drain plugs must also be removed while watercraft are being transported, as required by provincial law.
The province recommends that all watercraft and equipment leaving waterbodies within the Columbia River watershed undergo additional decontamination. A quaternary ammonium compound, such as Quat Plus, is the recommended cleaning agent.
Small items should be completely submerged in the cleaning solution for at least 10 minutes. Larger items should be sprayed and kept damp for the same length of time. Equipment can then be rinsed with clean water, provided the water does not come from the waterbody it has just left, and allowed to dry for at least 24 hours.
Anyone who spots a fish showing possible signs of whirling disease should leave it where it is and avoid transporting it. Photos and information about the sighting can be submitted to the province at whirlingdisease@gov.bc.ca
More information is available from the Columbia Shuswap Invasive Species Society at columbiashuswapinvasives.org or by calling 1-855-785-9333.
