Manitoba hopes potash will kill zebra mussels in Lake Winnipeg harbours

The Manitoba government plans to close four major harbours on Lake Winnipeg in an attempt to eradicate invasive zebra mussels.

Month-long closure could affect tourism, commercial fishing industries; experts disagree on potash strategy

Manitoba hopes potash will kill zebra mussels in Lake Winnipeg harbours

8 years ago
Duration 2:16
The Manitoba government plans to close four major harbours on Lake Winnipeg in an attempt to eradicate invasive zebra mussels

The Manitoba government plans to close four major harbours on Lake Winnipeg in an attempt to eradicate invasive zebra mussels, and one scientist thinks someone has "fouled up."

The small filter-feeding mussels reproduce aggressively and were first spotted in Lake Winnipeg's algae-ridden waters in October 2013.

Department of Fisheries and Oceans has worked closely with the province since then in determining a strategy to control zebra mussel populations.

Conservation Minister Gord Mackintosh said the province still needs approval from Ottawa, but it wants to dump tonnes of potash into the harbours at Gimli, Winnipeg Beach, Balsam Bay and Arnes, shutting them down from mid-May to mid-June.

Gerry Mackie, professor at the University of Guelph, said the most effective way of mitigating the threat of zebra mussels is to take a preventative approach.

"I believe in taking a proactive approach. That's been done and it hasn't worked ... somebody has fouled up." 

Makie said efforts to monitor boats and trailers coming into Lake Winnipeg from other water bodies has failed.

He thinks administering potash isn't ideal, but there are very few other options on the table.

"If it doesn't work, at least you've tried, you've reduced the population somewhat," said Mackie. "And by isolating into the harbours, it shouldn't have much of an impact, if any, on the lake itself."

Potash doubts

Potassium Chloride Aqueous Solution 20 per cent, commonly known as liquid potash, will be administered and monitored in the harbours by Ontario-based ASI Consulting Group Ltd. 

Mackintosh said the province is relying on one U.S. study that said liquid potash is effective in eradicating zebra mussels. That study took place in a small pond in Virginia, however, not a dynamic basin like Lake Winnipeg, the tenth largest freshwater lake in the world.

Lake Winnipeg expert Eva Pip has doubts the province's plan to dump potash in the lake to eradicate zebra mussels will work.

Pip, a University of Winnipeg biologist, said the invasive species has been found on both sides of the lake.

She said the mussels are no longer contained and will be almost impossible to eradicate.

"This will be a stop gap measure," said Pip. "We will be spending half a million dollars not knowing what the heck we're really doing."

Mussels are known to be sensitive to high levels of potassium, and Pip worries the potash will kill native mussels in Lake Winnipeg, which are already endangered or at-risk — like the mapleleaf mussel.

But Hugh MacIsaac, professor at University of Windsor’s Great Lake Institute and director of the Canadian Aquatic Invasive Species Network, said the potash treatment is engineered to target zebra mussels alone and doesn't kill other mussels or fish.

MacIsaac said the potassium-chloride solution is safer than alternatives.

"You can never say that it's not risky, but there have been studies done comparing potassium chloride ... versus many other types of molluskicides — poisons that kill mollusks — and potassium chloride was one of the safest ones."

Gimli harbour, one of four areas slated to close from mid-May to mid-June on Lake Winnipeg.

Mackintosh said the process could take a month, which means no fishing boats or leisure watercraft will be able to use those harbours.

Certain aquatic areas will be roped off with a silt curtain, and boats will be sent out to inject liquid potash into the lake

The potash treatment is allegedly not harmful to humans and any other aquatic life, but the closure will directly impact Lake Winnipeg’s tourism and fishing industries, forcing commercial fisherman ashore for an entire month.

Jocelyn Burzuik with the Gimli Harbour Authority said she was angry the province didn’t tell the people impacted directly.

“Our fishermen on Lake Winnipeg in the south basin only have the first two weeks to fish in this part of the lake," said Burzuik. "After that the fish start migrating north and they don't have access to the same amount of fish, so that means if [fisherman] don't get out on the water in the first 14 days of fishing season, their season is done.”​

Burzuik said now they have to scramble to find places for the boats that use the harbour and to ease the economic blow to those who rely on business from Lake Winnipeg. 

We just cannot sit by without taking action when the science tells us there is an option- Minister Gord Mackintosh

“And I am so shocked that we actually have to hear it from CBC Radio that they couldn't take the time two or three weeks ago, or longer when they discovered the zebra mussels back in October, and give us that information so we could plan.”

Stakeholders, province to meet

The province is set to meet with stakeholders tonight to see how they can ease the impact of the harbour closures.

Robert Kristjanson is a pickerel fisherman and his family has fished Lake Winnipeg since 1891.

"It's my life, that's what it is — It's my son’s life, my grandson’s life," said Kristjanson.
Cliff Carefoot, a boater on Lake Winnipeg, inspects the hull of a boat for zebra mussels.

Krisjansten said the province should have enacted more aggressive preventative measures sooner, because closing the harbour is not an option for him.

"It's a complete loss. You have three weeks in the spring when the waters cold to catch your fish."

He wants the province to compensate fisherman and business' impacted by the closures.

Stefan Tergeson owns a Gimli Clothing shop and is worried the harbour closure will also impact business surrounding Lake Winnipeg.

“Hopefully it's early enough that it won't affect us too much, the summer months of course are our busiest. But there's a lot of people that boat in the harbour and spend a lot of time there — the fisherman of course are a huge part of our community.”

Tergeson said he was happy steps were being taken, but that it won't be without an economic hit to Lake Winnipeg industries like his.

There is no plan in place yet to compensate those impacted, but the province said it's short term pain for long term gain. 

There will be a meeting of commercial fisherman on May 2 at 10:30 a.m. in the Gimli Council Chambers.

Treatment uncertain, action needed

"We just cannot sit by without taking action when the science tells us there is an option," Mackintosh said

The province is investing $500-thousand in the potash treatment, despite the fact that it isn't certain to cure Lake Winnipeg's zebra mussel woes.

Before and after: Manitoba Conservation Minister Gordon Mackintosh holds up a bare buoy and one covered with zebra mussels, an aquatic filter-feeding invasive species. (Jaison Empson/CBC)
But Mackintosh said the province has no choice.

"While it can't be certain, the only certainty that we do have at hand here is if nothing is done," said Mackintosh. "And if this isn't, if we don't make this application, the situation will certainly get worse​."

"This can be a really rapidly developing threat to the health of Lake Winnipeg and the economy, and the families that rely on Lake Winnipeg for incomes," Mackintosh said.

Zebra mussels, like all aquatic invasive species, can have a significantly negative impact on fresh water ecosystems, devastating native species and commercial fishing markets. Once they enter a system, it can be very challenging to manage or get rid of them.

Manitobans that come across the triangular clumps of mussels marked with zig-zag patterns can do their part by removing them from the province's waters.