Biologists test Bow River fish for whirling disease

Biologists are testing fish in the Bow River and other bodies of water near Banff National Park'sJohnson Lake to see if Canada's first case ofwhirling disease has spread.

• Whirling disease in fish found in Banff lake a 1st in Canada, officials say

Whirling disease discovered earlier this month in Johnson Lakeaffects trout and salmon, and can causeinfected fish to swim in a whirling pattern and die prematurely.

As a precaution, senior fisheriesbiologist Paul Christensen from Alberta Environment and Parks says biologists from his departmentand Parks Canadahave collected hundreds of fish from water bodies near the lake, which is just east of the Banff townsite.

"These are flowing systems sowe are looking in various reaches of the Bow River and some of the tributaries that feed into the Bow River," he said.

Difficult to 'get rid of'

"It can actually have a pretty profound impact on the fish population itself. Various lifestagesof this parasite are pretty persistent in the environment. There's a mix of spore stage thatcan last 30 years in the environment.Once it's in a system it's difficult, if not impossible, to get rid of it."

The disease is caused by the microscopic parasite myxobolus cerebralis, which can be transmitted to other water bodies through gear and equipment used for swimming, paddling, boating and fishing. It poses no risk to humans, but Parks Canada has banned fishing, swimming and other activities in Johnson Lake.

So far,the parasite hasn't been found outside ofJohnson Lake.

The parasite affects young fish of the "salmonids"family, which includes char, troutand whitefish in Alberta.

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