Invasive mussels in St. John River still at 'manageable' level, survey finds

The 22 zebra mussels found along the St. John River last year suggest levels of the invasive shellfish in New Brunswick's longest river are likely still manageable — for now.

That's according to a researcher leading the fight to keep them out of waterways before they multiply too quickly to prevent them from taking over docks, dams and drainage pipes.

"We're catching this very early," said Meghann Bruce, research scientist with the Canadian Rivers Institute. “We started monitoring...as soon as we knew they were connected to the system."

Zebra mussels are small shellfish that get their name from the zig-zag pattern on their shell. They get their bad reputation from their ability to overtake other species living in lakes or rivers, and the damage they inflict on hard surfaces they latch onto.

Bruce said the species has "infested" Lake Temiscouata in Quebec, which connects to the St. John River, also known as the Wolastoq, likely bringing juvenile mussels into this province.

Her team scoured 81 locations along the river between May and early November last year.

One of the hard surfaces researchers have come to realize zebra mussels could be prone to growing on is the Mactaquac Dam.

Nineteen of the 22 adult mussels Bruce's team collected were attached to N.B. Power's hydroelectric generating station just west of Fredericton.

Two others were found at the Beechwood Generating Station, about 25 kilometres south of Perth-Andover. Another was found at the junction of Belleisle Bay and the Wolastoq, making it the furthest downstream discovery the search has uncovered so far.

Bruce said it's still too early in their research to say for certain why the majority were found on the Mactaquac Dam. She believes the structure could be creating a "lake-like environment" as it slows the water's flow for zebra mussels to safely land.

While she couldn't put a dollar figure to the amount of damage zebra mussels have caused to infrastructure so far, she said they are "very problematic."

The institute has been working with N.B. Power for 10 years on various research projects, Bruce said.

It's why when the utility anticipated the species may pose a threat to its infrastructure, it enlisted Bruce to survey the river.

“Once they have colonized dams, management is required to stay operational," she said.