Thousands of zebra mussels ... One big issue

After a successful morning of walleye fishing, Don Pendergrass pulled his boat from Lake Mille Lacs before inspecting it for an invader - zebra mussels - that threatens the lake he loves. He removed a few weeds clinging to his trailer and drained lake water from his live well as conservation officers Luke Croatt and Scott Fitzgerald looked on.

The officers' presence this sunny day is part of the state's beefed-up enforcement and education effort to try to prevent the further spread of zebra mussels and other invasive species that threaten to permanently alter the ecosystems of Minnesota's treasured 12,000 lakes -- and possibly undercut its $4.7 billion sports fishing industry and the 1.4 million anglers who treasure it.

But some critics say a much tougher approach is needed. The stakes are too high, they argue, and the unfettered movement of boats among Minnesota lakes may have to stop. They point to California, where boats must be inspected before they are allowed on Lake Tahoe, and to Michigan, where programs similar to Minnesota's have failed to stop the spread of zebra mussels.

"The [Minnesota] system in place now relies primarily on education, awareness and voluntary action," said Dick Osgood, an aquatic ecologist, biologist and board member of Minnesota Waters, which represents 350 lake associations and citizens. "Funding is bare-bones minimal. It's cheap, feel-good and easy, but it's not that effective. That's why we have 200-plus lakes with Eurasian watermilfoil," an invasive plant that has raised havoc with lakes, fisheries and recreation.

First discovered in Minnesota in the Duluth harbor in 1989, zebra mussels now infest about 30 state lakes and rivers. Their further spread might be inevitable, based on experiences of states to the east, where zebra mussels were first found in the United States in 1988 after being discharged in ballast water by foreign ships on the Great Lakes.

"We have tried a pretty significant education campaign, with mixed results," said Gary Whelan of the Michigan Department of Natural Resources. "It continues to spread in our waters." About 250 of his state's 10,000 lakes are infested. "Regulations don't stop it either," he said. "Some people just ignore them. I don't think [zebra mussels] will get to all of them, but I'm sure a high percentage [of Michigan lakes] will end up with it."

Minnesota's situation isn't hopeless, said Luke Skinner, Minnesota DNR invasive species program supervisor. But the recent discovery of zebra mussels in four more Minnesota lakes -- Prior in Scott County, Pike near Duluth, Le Homme Dieu in Alexandria and Rebecca near Hastings -- underscores the difficulty of stopping the spread of a critter that in its larval form can be seen only with a microscope. They attach themselves to weeds, boats, docks or any solid objects. What's more, they're difficult to kill: A zebra mussel lived out of water in the DNR's Aitkin office for 10 days.

Many are watching Lake Mille Lacs, Minnesota's second biggest and arguably its most popular fishing lake. Not only is it huge, but it also has more than 400,000 boater visits yearly and is in the hub of the state's lakes region. The fingernail-size adult mussels were found in Mille Lacs in 2005, but the population now is growing exponentially.

"Zebra mussels have just exploded here," said Croatt, the conservation officer. "I've talked to at least a half-dozen anglers who have snagged mussels this spring." Last fall, residents found them on dock posts and boat hulls for the first time.

Tom Jones, a DNR fisheries biologist, has chronicled the growth while scuba diving in Mille Lacs. In 2007, he counted 130 mussels in 23 survey areas. "We found 24,000 in the same [areas] in 2008," he said. "I was stunned." Jones expects to find even more when he dives later this summer.

"It's frightening," said Pendergrass of Ham Lake, who frequently fishes Mille Lacs. "We don't want to lose our lakes."

Near Mille Lacs, billboards, newspaper ads and fliers left at launch sites warn boaters to drain their boats and check for weeds, and conservation officers, business owners and others are handing out cards and pamphlets. Officers are writing more citations and more summer boat inspectors have been hired.

But Osgood said only a tiny fraction of boats are being inspected at Mille Lacs, which has more than 40 public and private boat landings.

Jay Rendall, DNR invasive species prevention coordinator, said the state's efforts, boosted in recent years, have limited the spread of zebra mussels. The DNR has 80 seasonal watercraft inspectors this year, compared to 50 in 2007. More boats are being checked, and officials are working with resorts and lake associations. Signs are going up at all of the state's 2,500 public boat accesses. Last year, 49,000 boats and trailers were inspected.

"There's no question what we're doing is making a difference," Rendall said.

But Minnesota has more than 800,000 registered boats. Osgood said mandatory inspections of boats leaving all of Mille Lacs landings should be considered; state officials say that could cost $1 million a season.

Osgood said that would be money well spent. The culture that everyone is entitled to unimpeded access to lakes at no cost is being exploited by invasive species, he says. "It's Pollyanish to think we can keep that system and not in a very few years have a bunch of infested lakes," said Osgood. "And these things are permanent. Once zebra mussels get into a lake, there's absolutely nothing you can do."

Minnesota Waters recently issued a report calling the situation an "aquatic epidemic" and suggesting that a much stronger approach is needed. Existing laws, funding and programs are inadequate, and without drastic changes, the number of infested bodies of water will continue to grow, the report charges.

But Rendall said many of the recommendations are unrealistic. Minnesota has many more lakes than California. "We can't be everywhere all the time," he said.

Because of the Minnesota programs, the number of lakes infested by zebra mussels is much lower than in Wisconsin or Michigan, Rendall said.

Zebra mussels filter up to 1 quart of water daily and consume the tiny plankton that provide food for various lake and river inhabitants, including fish. When they show up, water clarity increases dramatically.

"We're going to see the water get clearer on Mille Lacs," Jones said, something anglers said is already occurring. The increased water clarity likely will promote weed growth and affect fishing. Eventually, anglers may have to fish at dawn, dusk or night to catch walleyes there, officials say. It's uncertain what the long-term impact will be to the fishery.

Meanwhile, just a mile from Mille Lacs on tiny Big Pine Lake, Angie Barnhart and her husband, Duane, worry that zebra mussels might spread to their lake.

"Whenever it's windy on Mille Lacs, boaters come here," Angie said.

The Big Pine Lake Property Owners Association recently strung a banner between two trees near the lake's only public boat access, urging boaters to check for weeds and mussels before launching. But Angie fears zebra mussels eventually will make their way to her lake, changing it forever.

"I'm afraid it's just a matter of when it will happen," she said.

Doug Smith • 612-673-7667