Zebra mussels found on a dock being installed on Minnesota’s Sand Lake are worrisome for resource managers both in the state and neighboring Canada.
That’s because Sand is a part of the Bowstring chain of lakes, which flows into the Big Fork River. The latter is a tributary of Rainy River, which feeds massive Lake of the Woods (65,000 miles of shoreline). And if that’s not enough, that lake drains into the Winnipeg River, and, ultimately, Lake Winnipeg.
Additionally, the closer the shellfish are to uninfected waters, the easier it is for them to be introduced on boats and trailers.
“It takes awhile for zebra mussels to establish through moving currents, but that potential is there,” said Cheri Zeppelin with the Minnesota Department of Natural Resources (MDNR). “The key is to slow down the spread.”
Across the border, meanwhile, fisheries managers had thought their resources were protected by the Canadian Shield, because lakes there don’t contain enough calcium for the invasive mussels to thrive. But this discovery raises the possibility that they could spread into northwestern Ontario without going through that natural barrier.
On the positive side, both the Lake of the Woods and Rainy River are low in calcium as well, according to Jeff Brinsmead with the Ontario Ministry of Natural Resources. That could diminish the likelihood of the mussels naturally migrating in river currents, but only time will tell.
The mussels found on the dock were dead adults, Zeppelin said. That means that they probably were alive until the dock was pulled out last fall.
Likely they were introduced by boaters, said Richard Rezanka, an invasive species specialist with the MDNR.
“This is the farthest north we’ve got them,” he said. “We’ve got pretty heavily fished lakes in the central part of the state, so it wouldn’t be outside the realm of possibility for water or zebra mussels to have been moved.”
(This article appeared originally in B.A.S.S. Times.)