This story was originally published Sept. 30.
There's growing concern in Alberta about the new threat to provincial ecosystems posed by whirling fish disease, which was first detected last month and has now turned up in several lakes and streams. But the parasitic infection joins an already long list of invasive species provincial officials are on the lookout for.
1. Whirling fish disease
According to Barry Gibbs, executive director of the Alberta Invasive Species Council, whirling fish disease has become a big enough concern to land on his list.
The infection affects trout and salmon, and can cause infected fish to swim in a whirling pattern and die prematurely.
On Thursday, the Canadian Food Inspection Agency confirmed that the disease, first detected in Johnson Lake, has now been found at six more locations in waterways near Banff National Park.
Whirling fish disease has the potential to wipe out up to 90 per cent of a trout population, according Alberta Environment and Parks biologist Roger Ramcharita.
The disease can be transmitted through equipment used for swimming, paddling, boating, water pumping and fishing, or through infected fish and fish parts.
2. Zebra and quagga mussels
The battle to keep Alberta free of zebra and quagga mussels is also an important one, and it's going well, Gibbs says.
The fingernail-sized freshwater mollusks get attached to boats and can choke out native species and clog water intake pipes and machinery once they get established.
The province's mandatory boat inspection program, which uses specially-trained sniffer dogs, has so far been effective in keeping the creatures out.
The mussels can live out of water for up to 30 days and once they get established are difficult to eradicate.
3. Flowering rush
Flowering rush, a prohibited noxious weed, has been identified in 12 locations around Alberta, including Lake Chestermere east of Calgary, says Gibbs.
(Prohibited noxious and noxious are terms used in the Alberta Weed Control Act: Prohibited noxious weeds must be destroyed and noxious weeds must be controlled).
The cattail-like perennial infests bays and shorelines, pushing out native vegetation and growing into impenetrable thickets.
Before it was banned, the pretty, pink plant — which is native to Europe, African and Asia — was popular as a decorative plant in water features, and was even sold commercially for a time.
"It's a big concern," he said. "There is a lot of work underway to try to find ways to control it."
The province is working with officials in Idaho and Montana to develop an effective herbicide.
4. Hawkweed (meadow and orange)
The province is also trying to stamp out two prohibited forms of hawkweed — meadow and orange.
Meadow hawkweed looks a lot like a dandelion, while the orange version is pretty enough to be a tempting for gardeners to plant as an ornamental.
But the invasive plant, with its high rate of seed production and asexual germination, quickly becomes a problem.
"All of these characteristics facilitate rapid colonization and monopolizing of resources. An undetected patch of hawkweed has great potential to become an ineradicable infestation," according to the Alberta Invasive Species Council's website.
5. Spotted knapweed
Spotted knapweed, which was brought in from Montana, is another prolific seed producer that has become a big concern in Alberta, Gibbs says.
An aggressive colonizer originally from Eastern Europe, the weed gives off a substance that interferes with the ability of its competitor plants to reproduce.
Once it takes root in pastureland, it is extremely difficult for ranchers to get rid of it.
"Knapweeds have become well known because of their almost wholesale degradation of large tracts of rangeland in the northwestern U.S. and parts of southern B.C.," according to the Alberta Invasive Species Council's website.