Whirling disease now infects entire Oldman River basin, including Waterton Lakes National Park

A deadly fish disease that has already spread through Banff National Park has now infected a wide swath of territory to the south, including Waterton Lakes National Park.

Deadly fish disease has spread southward after infecting Bow River basin, says Canadian Food Inspection Agency

Whirling disease has been observed in the United States since the 1950s and is prevalent in the western and northeastern states. (Mike Lawrence/The Gleaner/Associated Press)

A deadly fish disease that has already spread through Banff National Park has now infected a wide swath of territory to the south, including Waterton Lakes National Park.

The Canadian Food Inspection Agency (CFIA) declared the entire Oldman River watershed infected on Monday, including all streams, creeks, lakes and rivers feeding into the river.

The Canadian Food Inspection Agency (CFIA) has declared the Oldman River watershed infected with whirling disease, expanding the reach of the deadly fish illness far to the south from where it was previously detected in the Bow River watershed. (Government of Alberta)

This comes after the CFIA declared the entire Bow River watershed infected with whirling disease in February.

Monday's declaration expands the impacted area southward, all the way to the Canada-U.S. border.

Despite the declaration, Alberta Environment and Parks said there are currently no plans to change fishing regulations in the Oldman River basin.

This map shows the area that was previously declared infected with whirling disease, in the Bow River watershed, before it spread southward into the Oldman River watershed. (CFIA)

The CFIA said the rest of Alberta remains a "buffer zone" for the disease, meaning all provincial aquaculture facilities and Class A fish farms will have to test fish for whirling disease.

Those wanting to stock fish from the affected area would also have to implement "approved biosecurity protocols" in order to obtain a permit from the CFIA.

What is whirling disease?

The disease predominantly affects trout and whitefish and can cause them to swim in a whirling pattern and die prematurely.

Infected fish can also exhibit skeletal deformities and their tails can turn a darker colour, even black.

The presence of whirling disease in Alberta was first detected in the upper Johnson Lake in August 2016, and then in the Bow River the following month.

The disease is not harmful to humans and the CFIA said there are no health concerns for people using the infected bodies of water or eating infected fish.

There are no known treatment options for whirling disease and officials are focusing their efforts on preventing it from spreading.

In Banff National Park, there is a plan under consideration to remove virtually all fish from Johnson Lake in response to the disease.

What you can do

To help prevent the spread of the disease, there are several things boaters and anglers can do.

The province advises all motorized boat users to pull the drain plugs before transporting their watercraft and ensure boats are cleaned and dried before being put in a new waterway.

Bait fish should never be released into waterways.

If you suspect a case of whirling disease, you are asked to call 1-855-336-BOAT (2628).