Zebra mussel discovery in N.B. triggers meeting of scientists
It may be too late to stop St. John River invasion, but other waterways could be spared, gathering told
The discovery of a single adult zebra mussel in the St. John River sparked a recent gathering of scientists and researchers who knew the find was all but inevitable.
The invasive mussel was found on a floating dock pulled up in Mactaquac in December, and the number could easily become millions in a few years, scientists said.
"If they've taken hold in significant numbers they're almost impossible to eradicate," said Terry Melanson, the team lead with the aquatic invasive species program with the Department of Fisheries and Oceans.
"You cannot eradicate them once they're in the system, that's been the experience so far."
That's why more than 60 representatives of watershed groups and various government agencies and departments, including the Federal Department of Fisheries and Oceans and N.B. Power, met in Fredericton for a day-long strategy session organized by the New Brunswick Invasive Species Council.
"We're also getting everyone up to date on what the situation is here in New Brunswick and what's being done currently," said Sarah Cusack, project co-ordinator with the council.
It may be too late to prevent zebra mussels from inhabiting the St. John River, but it's not too late to prevent the mussels from taking over other major New Brunswick waterways, the gathering was told.
Zebra mussels are a highly invasive species that reproduce rapidly and can transform an ecosystem if the mussels get a foothold.
The mussels' sharp shells can disrupt beaches and swimming areas. High numbers in intakes can clog up infrastructure such as hydroelectric dams and drinking-water systems.
And populations of millions of zebra mussels can filter nutrients out of waterways, denying these to local species.
Numbers shared by the Department of Fisheries and Oceans show that in 2022, zebra mussel colonies in Lake Témiscouata in southeastern Quebec, about 300 kilometres upriver from Mactaquac, were recorded at about 150 mussels per square metre.
That number grew to 2,500 in the same area in 2023, and to 35,000 per square metre last year.
Studies have looked at the cost of allowing zebra mussels into waterways, which would be higher than the cost of keeping them out, the meeting heard.
In British Columbia, for example, the cost would be an estimated $64 million to $129 million annually if the mussels were to be introduced into the province, said Martina Beck, unit head with the provincial Ministry of Water, Land and Resource Stewardship.
She gave a presentation to the group in Fredericton about the costly impact of zebra mussels on municipal water supplies, hydro power, agriculture, irrigation systems, tourism and property values.
"We certainly know that the cost of preventing their introduction is far less than what it would cost to address them once they've established," Beck said.
B.C. has focused on prevention and adopted legislation that asks boaters to drain their boats or face a $400 fine. The province has also retained a pair of canine units trained to sniff out the invasive species on boats being transported. Both are strategies that could be considered in New Brunswick, Beck said.
In New Brunswick, a national "Clean, Drain, Dry" campaign for transporting boats overland will ramp up, but the province has been less aggressive than B.C.
Boat wash stations in Edmundston, Nackawic and Mount Carleton Provincial Park have been built in response to the zebra-mussel detection in Quebec, with more planned for this summer. But there's been no legislation to get boaters to act to keep the invasive species at bay.
"It's all messaging that's hoped to be taken up as a 'Do it yourself' kind of thing," Cusack said. "From my understanding there's no enforceable aspect to that."
Signs of invasion 3 years ago
Charles-Oneil Crites, a chemistry professor at the University of Moncton campus in Edmundston, has been studying the water coming into the St. John River system. Two years ago, he estimated millions of zebra mussel larvae were flowing into the province from the population discovered in Lake Témiscouata in 2022.
"There was 300 million individuals exiting the Madawaska River, going into the St. John River, every day," said Crites. "That means there is a significant amount of larvae that could potentially settle somewhere."
What number of those larvae will be able to attach to an area, mature and reproduce is a "probability game," according to Crites, who said larvae can face one-in-a-million odds, depending on the environment they find.
Briskly flowing rivers decrease the odds, and calmer waters often increase them. While the St. John River will likely see an increase of zebra mussels in the years ahead, Cusack said, it's not too late to prevent zebra mussels from hitchhiking to other rivers and lakes and colonizing them.
"The St. John River, yes, [zebra mussels] are going to spread through naturally," Cusack said. "The thing that's not naturally going to happen is it getting into the Miramichi River, the Restigouche River, other systems that are not connected to the St. John."
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