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Whirling disease is a microscopic parasite by the name of Myxobolus cerebralis that affects trout, whitefish, and salmon. In Alberta, species most likely to be affected by whirling disease include Rainbow Trout, Cutthroat Trout, Mountain Whitefish, Brook Trout and Brown Trout. Though the effect on fish in the salmon family can be different depending on species and the water body, young fish have the highest mortality rate. 

North Saskatchewan River Watershed Declared Infected

Whirling disease has been detected upstream in the North Saskatchewan River watershed. While whirling disease may not be present in all water bodies within a declared watershed, it is a threat to water bodies in Edmonton if we do not take action.  

How to Spot Whirling Disease

  • Fish is swimming in a whirling fashion; the parasite damages both the nervous system and the cartilage
  • A crooked tail that may or may not be black as a result of nerve compression
  • Spine and head may become deformed
  • Shortened operculum (gill cover)

Please note that whirling disease is not harmful to humans, it only affects fish in the salmon family, including trout, char and whitefish. If you suspect you witnessed a fish with whirling disease, please call the provincial hotline at 1-855-336-BOAT (2628) or email

How to Stop the Spread

Alberta Environment - Clean - Dry - Drain Your GearWhirling disease is spread through mud, water, dead fish and plant parts.

  • CLEAN DRAIN DRY your gear including your boat, waders, boots, anything that comes in contact with the mud or water
  • Pull the plug on your boat to allow for any standing water to spill out while you drive - it’s the law in Alberta
  • Clean your gear away from any storm drains, a grassy area works best

For more information, please visit Clean, Drain, Dry Your Gear.

For More Information

Integrated Pest Management (IPM)

Online Contact 311 Online

In Edmonton: 311
Outside Edmonton: 780-442-5311

TTY 780-944-5555

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