If you plan to swim, sail, kayak or fish on Lake Winnipeg this summer, be on the lookout for zebra mussels.
The request to lake users was issued Wednesday by the Selinger government in a plea for people to look for and report any spotting of the invasive aquatic pest.
The appeal came as Conservation and Water Stewardship Minister Gord Mackintosh told reporters a 25-day-long bid to control the spread of zebra mussels at four Lake Winnipeg harbours appears to have been a success. Harbours at Winnipeg Beach, Gimli, Arnes and Balsam Bay were sealed off and treated with liquid potash containing potassium that killed sample mussels put in the water by officials. The treatment ended Saturday and all harbours are now open to the public, without restrictions.
No help with algae
Do zebra mussels eat algae? Could they be the saviours of Lake Winnipeg?
Yes and no.
Rob Nedotiafko, the province's co-ordinator for the project to eradicate zebra mussels at four Lake Winnipeg harbours, said the mussels consume naturally-occurring green algae and are quite efficient at cleaning lake water and making it clearer.
But they don't eat blue-green algae, the type currently plaguing Lake Winnipeg because of high nutrient loads.
"What they don't pull in is blue-green algae, the toxic algae that we're very concerned about," Nedotiafko said.
By just chowing down on green algae, zebra mussels disrupt the natural food chain, he added.
With less green algae, other organisms have less to eat, which means less food for fish.
"There is sort of a whole systematic ecological shift in the food chain and the science of the lake," Nedotiafko said.
Zebra mussels in Lake Winnipeg were first detected last fall.
"We do see this as a battle in what is likely to be a long-term war," Mackintosh said. "That is the likelihood."
Mackintosh said efforts now focus on determining if the mussels are anywhere else in the lake and to control any further introduction to the lake.
"We want to deputize every Manitoban and indeed every visitor to this province," he said. "Vigilance will be critical on a go-foward basis."
Provincial biologist Laureen Janusz said the focus this summer is to determine whether any zebra mussels have made a home on rocks at the bottom of the lake.
Janusz said lake users should look for a small D-shaped shell attached to rocks, pipes and dock undersides about one foot below the surface.
"If you're walking along and you see something attached to a rock and you physically have to really pull quite hard to pull it off... in the end, that's what you're looking for," she said. "At that point we'd appreciate getting a phone call."
Mackintosh also said over the course of the summer the province will conduct about 270 tests to detect any mussels on Lake Winnipeg, Cedar Lake, Reed Lake, Cranberry Lake and Eden Lake. Divers will also be scouring known reefs and the Lake Winnipeg Research Consortium's research ship, Namao, will look for any mussels during its travels.
To gauge just how severe the zebra mussel invasion is, metal substrate samplers will be dipped in about 30 harbours around the province to see whether they attract any mussels. Docks, buoys and boats being pulled out of the water in the fall will also be inspected.
The province will also mount a wider containment effort by inspecting boats coming from out of province.
To that end, the province has recruited Manitoba Hydro. The Crown utility has purchased three portable decontamination units valued at approximately $85,000, bringing the total number of units in the province to five. The decontamination units are high-heat, high-pressure mobile units that purge aquatic invasive species from the undersides of boats.
"Manitoba Hydro wants to stop the spread of zebra mussels," Manitoba Hydro president Scott Thomson said in a statement. "The impact they could have on our generating stations is significant."
Zebra mussels have not been detected on the Winnipeg River system, where Hydro has a series of generating stations.
The decontamination units will be stationed in early July at locations such as Manitoba border entry points and busy boat-launch sites such as Gimli, Winnipeg Beach and Selkirk Park.
Progressive Conservative critic Shannon Martin said the increased surveillance for zebra mussels is welcome, but it may have taken the government too long to deal with the aquatic menace.
"You ask any of the scientists involved: Once zebra mussels get into the water system, I think they're here for good," Martin said. "The announcement of a longer-term strategy is long overdue."