Fishers worried after invasive zebra mussels detected in Lake Manitoba

ST. LAURENT, MAN. -

The detection of young, microscopic zebra mussels has people who use Lake Manitoba concerned.

The invasive mussels were found in water samples collected by the province last month from three locations at The Narrows.

For those who rely on the lake to make a living, the discovery has left them worried about the impact on the ecosystem.

Allan Gaudry has been a commercial fisher on Lake Manitoba for 30 years and has a keen interest in what happens in the water.

“We have never seen any sign of zebra mussels in our gear and to us it was kind of a shock to hear that we’ve been invaded with zebra mussels,” Gaudry said.

The Manitoba government said zebra mussel veligers, the young microscopic form of the aquatic invasive species, were detected in nine water samples collected last month from the Lake Manitoba Narrows.

They’re so tiny you can’t see them but their presence at The Narrows may be indicative of a larger population.

“We can’t pinpoint exactly when we got zebra mussels. This is the first evidence we have of them,” said Jeff Long, Manitoba’s manager of fisheries science, fish culture and aquatic invasive species director.

It’s not the first time they’ve been found in Manitoba. The province has been monitoring for the mussels in Lake Manitoba ever since they were first detected in Lake Winnipeg in 2013.

Long said more sampling is needed to determine where else in the lake the mussels may be located.

“They’re free floating in the water column,” Long said. “So that means we didn’t pick up one needle in a haystack. We don’t know how many needles there are in this haystack but we picked up more than just the one that happens to be there.”

The overland movement of watercraft between bodies of water is the main way mussels spread. The discovery in Lake Manitoba means boaters and watercraft users on the lake now face new requirements to stop the spread.

“The reason being is because we can’t have people moving veligers around because they can’t see them,” Long said. “So containment is the first step.”

The province said any boats or watercraft that have been in Lake Manitoba must now be decontaminated before being put in another body of water. You can expect to see new signage around high traffic areas like boat launches reminding people to do so.

Manitoba has five water inspection and decontamination stations set up across the province which do about 20,000 inspections each year. People can also decontaminate equipment on their own.

Gaudry represents 450 members of the Lake Manitoba Commercial Fishermen Association. They only fish commercially in the winter but would like to see more than five stations set up.

“Obviously, we’ve been impacted with zebra mussels,” said Gaudry. “There’s other accesses, so why isn’t there more done.”

He’s worried about the impact the mussels could have on the fishery, concerned the discovery is only the beginning of a larger problem.

Zebra mussels, which can reproduce quickly, can impact fish populations by consuming large quantities of algae.

The province isn’t ruling out anything when it comes to more water inspection stations but Long said they can be cost prohibitive to run. The service is free to use and Long said he’d like to see more people use the stations that are already set up.

“Perhaps it’s not that we don’t have enough stations, perhaps it’s that people aren’t using them enough,” he said. “We’re contemplating all of the aspects that go into this.”