A deadly fish disease discovered for the first time in Canada in late August has now spread to the Bow River, Canadian Food Inspection Agency officials confirmed Monday.

Whirling disease affects trout and salmon, and can cause infected fish to swim in a whirling pattern and die prematurely.

After the disease was first detected in Johnson Lake in Banff National Park, officials began testing nearby waterways to see if it had spread.

They confirmed the presence of whirling disease in the upper Bow River, downstream from the confluence of the Bow River and Cascade River within Banff National Park.

Sample results from the Sam Livingstone Provincial Fish Hatchery in Calgary and the Cold Lake Provincial Hatcheries tested negative.

Work is underway to collect samples from basins immediately adjacent to the Bow River, including the Oldman River and upper Red Deer River watersheds.

Results will be reported by the CFIA as they are received.

Bow River attracts fishers from all over the world

The owner of Calgary-based Out Fly Fishing Outfitters says people come from all over the world to fish for trout on the Bow.

"People come here because they want that hard-fighting, exceptional wild fish," Josh Nugent explained.

"If whirling disease were to take hold on the river, it gives people less reason to come here."

'Serious impact'

Alberta Environment and Parks biologist Roger Ramcharita says it's a serious problem.

"It's possible — in fact, it's highly likely — that of course it's spread within the Bow system into the province of Alberta outside the park." Ramcharita said.

At its worst, whirling disease can wipe out up to 90 per cent of a trout population, he said.

"The bottom line is, it can have a very serious impact on trout populations for a period of time, which could be years."

Action plan

To further prevent the spread of whirling disease, Alberta is

quarantining all commercial fish culture operations until each facility has tested negative for whirling disease, and

ceasing provincial fish stocking until each of the five facilities has tested negative for the disease.

In order of potential risk, from highest to lowest, the movement of fish, mud or sediment and water can spread whirling disease.

It can be transmitted through equipment used for swimming, paddling, boating, water pumping and fishing, or through infected fish and fish parts.

The province is therefore urging anglers, boaters and recreational water users to thoroughly clean all of their equipment and remove any water, mud, or plant material from their property before and after each use.

Alberta Environment and Parks will establish a special committee with representatives from various federal agencies to implement procedures to identify, test and manage whirling disease.

The province has asked that whirling disease be added to the agenda at the upcoming Canadian Council of Ministers of the Environment at the end of September due to its potential economic and recreational impact.