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Alberta Fish Contaminated: Whirling Disease Spreads
29 May
Summary
- A microscopic parasite has caused a federal order for the Athabasca watershed.
- Whirling disease affects juvenile fish, causing them to swim erratically.
- Alberta's endangered rainbow trout now face an additional ecological threat.
Central Alberta's Athabasca watershed, covering a significant portion of the province, has been designated a contamination zone by the Canadian Food Inspection Agency (CFIA) due to the confirmed presence of whirling disease.
The microscopic parasite, Myxobolus cerebralis, attacks the cartilage and nervous system of young fish, causing a distinctive whirling swimming pattern that hinders feeding and increases predation risk.
This federal order strictly controls the movement of fish and sediment within the 159,000-square-kilometre watershed, although recreational activities remain unaffected. The disease has so far only been detected in the McLeod River.
Whirling disease has a history of devastating fish populations, notably causing a 90 percent decline in trout in Colorado during the 1990s. As Alberta reaches the 10-year mark since the disease's initial detection in 2016, concerns are rising about potential population-level impacts.
Endangered rainbow trout populations in the region face this new threat, compounding existing environmental pressures from land use. Parks Canada has implemented urgent measures, including watercraft restrictions in national parks, to prevent further spread.
While northern watersheds were once thought to be protected by colder temperatures, this assumption is being challenged, indicating the parasite's adaptability and potential to threaten a wider range of species across Alberta.
