Invasive species began appearing in Minnesota's lakes and rivers about 150 years ago when the German carp was brought to America as a food source.
They were, and still are, an environmental disaster.
The prolific fish roils up water, roots out plants and can outcompete native fish, basically destroying a lake or pond.
Since then, the list of invasives has grown, especially as it became easier to move from country to country. Among the newest threats is another carp, only this time, from Asia . Bighead, grass and silver carp are in the Mississippi River below Minnesota, though a few bighead and silver carp have been found in Minnesota waters. There is fear all three carp species will hit this region in much larger numbers, causing major problems. For example, the silver carp is known for jumping out of the water and can injure boaters.
Aside from carp, the state's waters and wetlands have been hit with at least a dozen more invasives. In this region, the worst offenders are zebra mussels, Eurasian watermilfoil, purple loosestrife and curly-leaf pondweed.
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"They definitely have an impact," said Heidi Wolf, head of the Department of Natural Resources aquatic invasive species section. "No one wants to swim in Eurasian watermilfoil."
Eurasian watermilfoil can choke boat motors, zebra mussels can clog water intakes and cut feet and curly-leaf pondweed can make it nearly impossible to fish some lakes.
"We've had them here for a while," she said. And while the list of infected waters covers 27 pages, that's less than 1 percent of the state's waters. The goal now is to try to keep that list as small as possible.
More options
Though a lot of invasives here and more could be coming, "it's not inevitable," Wolf said.
The DNR and other agencies have fought back with beetles that control loosestrife and chemicals that have knocked out zebra mussels. "As time goes on, there are more and more options," she said.
Because Asian carp aren't here yet, the DNR has focused on a plan with 35 options for keeping them at bay.
But Wolf emphasized that education and vigilance are still needed because prevention is the key.
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Zebra mussels have been particularly bad on the lower part of Lake Pepin, said Mike Davis, a DNR aquatic ecologist who specializes in mussels. "They have definitely had an impact, they sure have," he said.
On Pepin, zebra mussels were at first so prolific that they suffocated native mussels. He believes there was a 50 percent loss of native mussels because of invasives. Since then, zebra numbers have waxed and waned, dying back every few years.
"We don't see that blanket forming quite as much," he said.
A collaborative approach
Tina Wolbers, one of the DNR aquatic invasives planners, said the DNR is continuing to push its program to stop more invasions. The Legislature allocated $10 million this year to give to counties so they could also fight invasives, she said.
A big part of the problem is that Minnesota is blessed with so many lakes and rivers. The state has 2,155 public boat launches and there are thousands of private accesses.
"I don't think there is one best answer," she said. "It's a collaborative multi-pronged approach."
Part of that approach involves Jen Wahls, who was recently hired as Wabasha County's aquatic invasive species coordinator. The county got $100,000 from the state for its work.
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Wahls said that state and federal officials are watching Lake Pepin and Lake Zumbro pretty well, so she decided to focus the county's efforts on trout streams.
There are seldom any boats on trout streams, she said. At the same time, the county has 18 designated trout streams and there are some invasive plants and animals in Lake Superior that could really harm those streams.
All it would take would be one angler to get viral hemorrhagic septicemia or didymosphenia geminata, commonly known as rock snot, on their boots in Superior and then fish a Southeast Minnesota trout stream "and there we go, we have a problem," she said. "I don't know a way of getting rid of it."
Also, the New Zealand mudsnail has been found in south-central Wisconsin and she's afraid of whirling disease, which kills trout. Japanese pondweed has been found in Hammond Creek, she said. It probably was used as an ornamental plant and got away.
She wants to make anglers and hikers aware of potential problems and offer solutions, such as brushing off boots and not wearing boots with felt bottoms because they can more easily move species. One idea is to place signs at places where trout anglers go onto easements, warning of the problems, she said.
Worried biologists
On the Mississippi, "right now, we're in a bit of a holding pattern," said Megan Moore, an aquatic plant biologist with the DNR's Long Term Resource Monitoring program.
Purple loosestrife and Eurasian watermilfoil have been around for a while. A few years ago, some water lettuce, water hyacinth and parrot's feather, all invasives, were found on river backwaters south of Kellogg. A hard winter killed some, and others were controlled by pulling them out by hand, she said.
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She thinks people bought them for their backyard ponds and the plants got out somehow.
If it's in an isolated backwater, "boom, it takes over," she said. But for the whole river, "I don't see the plants changing the river, at least not the way people thought they would," Moore said.
Gary Montz, a DNR invertebrate expert, said zebra and Quagga mussels, spiny waterflea, and the Asian carp as the worst bad guys for him.
Waterfleas are tiny, but they can eat up much of the zooplankton that is the basis of the food chain, he said. "Biologists as a whole get really worried about things like that."
Determining just how bad zebra mussels might be is hard to tell, Montz said. They came into the state in the 1980s and reached inland waters, beginning with Lake Zumbro, in 2000.
"That is not all that long in our ecosystems to have a really good handle on how our lakes and how our fish populations and other aquatic populations will respond to this," he said. "Right now, we don't have a lot of successful options."
