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Zebra mussels in the Red

Grand Forks Herald


They're not at the problem stage—yet—but zebra mussels seem to be more abundant this summer in the Red River than they've been since larval-stage mussels first were detected in 2010 near Wahpeton, N.D.
 

"Just in general, it does seem like we have been getting more reports this year," said Jessica Howell, aquatic nuisance species coordinator for the North Dakota Game and Fish Department in Jamestown.

The free-floating larvae, called veligers, were found in 2009 in Pelican Lake in Minnesota, and by the next summer had drifted down the Otter Tail River into the Red.

The microscopic veligers ride the currents until they're large enough to find a place to attach, but until this summer, adult zebra mussels were relatively scarce in the Red River.
That appears to be changing, Howell said.

"It seems the population is starting to expand quite a bit," she said.

The invasive mussels, which are about the size of a man's thumbnail, are notorious for congregating in large numbers, degrading habitat for spawning fish, clogging water intakes and crowding out native mussels.

Simply put, they're like the aquatic version of an uninvited houseguest. The Red River is the only place in North Dakota where zebra mussels have been confirmed.

"They can reproduce really fast, but in rivers, it's always kind of hard for them" to establish because of the current, Howell said. "I just think this year happened to be the right conditions for them at the right time."

Howell said she checked sites below dams in Fargo, Grand Forks and Drayton, N.D., on Monday, Aug. 13, as part of routine sampling she conducts from April through October. She hasn't had a chance to analyze the water samples for veligers, but Howell says she found adult zebra mussels on the first rock she checked below Riverside Dam in Grand Forks.

Finding adult zebra mussels in Drayton didn't take long, either, she said.

"The water had come down, and boy, there were zebra mussels on those rocks," she said.

The Midtown Dam site in Fargo didn't produce any adult zebra mussels, but Howell says she suspects the abundance of concrete at the site is less conducive for them to attach.

"I expect there are quite a few zebra mussels (in Fargo), just maybe not where I was working," she said.

Zebra mussels also are beginning to show up on Grand Forks' water intake structure on the Red River, said Fred Goetz, supervisor of the city's Water Treatment Plant. Divers last winter checked intake structures on both the Red Lake and Red rivers, Goetz said, finding mussels near the bottom of the Red River intake but none on the Red Lake River.

Divers first started checking the intake structures in 2016, conducting the inspections in the winter when the river is less turbid, he said.

"They have not been a problem for the intake structure itself," Goetz said. "They aren't on the actual screens, they are on the very bottom of the structure that sits on the river."

As populations build, Goetz says he expects the zebra mussels will begin accumulating on the screens.

"We're trying to figure out what we're going to do when they become a problem," he said. "They're going to. We have to come up with a plan, and we'll be working toward that soon.

"The biggest thing is we don't want them to start going up the pipe."

Last fall, workers didn't find any zebra mussels when they removed city docks from the river, which Goetz says surprised him. Whether that changes this fall remains to be seen, but anglers have reported seeing zebra mussels in city limits.

Joe Greenwood of Grand Forks said he has pulled up zebra mussels with his anchor rope twice in recent weeks, first on a flat rock and then on a small piece of wood, both times near the LaFave Park boat ramp in East Grand Forks.

"I was surprised by that," Greenwood said. "I thought that first one was something special, and then I got these other ones, and I thought, 'Oh boy.'

"It's kind of frightening. I hadn't been out that much, really, and I haven't seen them anywhere else except right there, either."
Zebra mussels basically are impossible to eliminate once they're established, so it's crucial that people follow the "Clean, Drain and Dry" slogan when leaving the water, Howell said.

Prevention is the best, if not the only way to keep zebra mussels at bay, she said. On the Red River, that means draining water from bait buckets upon leaving the river.

State law in both North Dakota and Minnesota also requires removing drain plugs from boats during transport and draining livewells and bilges; having zebra mussels in possession also is illegal.

Zebra mussels can live up to 28 days in moist conditions, even if they're not in the water, Howell said.

"That's why we recommend people let things dry out completely," she said. "They'll die a lot faster if they can dry out."