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Suspected whirling disease case threatens fish in Yoho Park

Invasive parasite deadly to fish has not previously been confirmed in B.C.
Rainbow trout infected with whirling disease which damages the backbone of the fish causing them to swim in a “whirling” pattern. (Photo: Sascha Hallett,

Parks Canada says it is responding to a suspected case of whirling disease in Yoho National Park, in British Columbia’s southeast Rocky Mountains.

A statement from Parks Canada says it’s the first time the parasite that causes the disease has been detected in the province.

It says young fish, such as rainbow and brook trout, are especially susceptible to whirling disease, with a mortality rate of about 90 per cent.

The statement says once established it’s nearly impossible to eradicate the parasite, which is a known aquatic invasive species.

In order to prevent further spread to other waterbodies, Emerald Lake, Emerald River, Peaceful Pond and One Duck Lake, along with their shorelines and tributaries, are closed.

The statement says all watercraft, water-related gear and angling are prohibited with fines for violations reaching up to $25,000.

READ ALSO: Concerns raised about possibility of invasive fish disease in B.C. waters