Sunday, February 5, 2023
More from MPR


Managing cormorants on Leech Lake
Larger view
Conservation workers are using blinds to shoot cormorants on Little Pelican Island on Leech Lake. They have killed more than 2000 birds so far. (MPR Photo/Stephanie Hemphill)
The population of cormorants on a small island in Leech Lake is booming. Or it was. Natural resource managers have killed more than 2,000 cormorants there in the past month. They think the cormorants are eating too many fish - especially the walleye and yellow perch people love to eat. Critics say there's not enough evidence to justify the killing.

Walker, Minn. — Larry Jacobson is the third generation in his family to run the Hiawatha Beach Resort, on the west side of Leech Lake. Three years ago on fishing opener weekend, all of his 21 cabins were full. This year, he had no guests.

Jacobson says the word has spread that there's trouble on Leech Lake. He blames the cormorants. They've been nesting on a small island in the south end of the lake. Eight years ago there were 50 nests; last year there were 25-hundred.

"The cormorants eat about 1 pound fish a day," says Jacobson. "The way the population was just exploding out there, you could see writing on wall, that it was going to have a dramatic impact. It eventually showed up in walleyes, perch, tulibee."

Jacobson says his guests were still catching big walleye, but the smaller, pan-sized walleye were getting hard to find.

In the last seven years, a lot of young walleye didn't survive bad weather when they hatched. The fish that hatched out in 2001 grew through the summer and continued to thrive in the protected bays on the west side of the lake. But they disappeared in the open lake, where cormorants feed.

Jacobson and others who operate businesses in the area have been asking the DNR to do something about the cormorants.

"Leech needs to be maintained as high quality fishery," he says. "There's such an economic impact to the area from walleyes, if you don't maintain it that way, everyone's going to be suffering."

Resource officials are responding to the resorters' concerns. John Ringle is wildlife manager for the Leech Lake Band of Ojibwe.

He aims a small boat at Little Pelican Island, three miles off the south shore of Leech Lake. It's about three acres of sand and scruffy shrubs. A single dead tree pokes up, with two or three black birds perched on the broken limbs.

On the ground are hundreds of cormorants. Ringle says they fish out here in the open waters of Leech Lake.

"They're omnivorous, so they're eating all sorts of different varieties of fish," he says. "Right now they're probably eating large numbers of perch. And that may have some significant influence on what's happening with the walleyes, because perch and walleyes cycle very closely."

Ringle is working with the Minnesota DNR, the U.S. Fish and Wildlife Service, and the Agriculture Department's division of Wildlife Services to reduce the number of cormorants nesting here.

Normally cormorants are a federally protected bird, just like eagles. But a new rule allows resource officials to harass and even kill cormorants where they're damaging other wildlife.

On Little Pelican Island, two blinds rest on wooden posts above the land. This spring and summer, workers are sitting in the blinds and shooting cormorants.

"They'll go up in the blinds early in the morning without disturbing the other birds, do the culling activity in the morning, come out and retrieve the birds, and be done, usually by noon," says Ringle.

They use air rifles, to make as little noise as possible.

So far they've killed more than 2,000 birds. They're collecting the bodies to incinerate them. They plan to leave about 500 nesting pairs.

Back on shore, Ringle says nobody's happy about shooting cormorants. But he says he thinks it's necessary.

For one thing, there's a small colony of common terns living on Little Pelican Island. And contrary to its name, the common tern is actually a threatened species. This is one of only four known nesting spots for the common tern in Minnesota. And Ringle says they're being squeezed out.

"The cormorants have pushed the gulls, which in turn have pushed the terns," he says.

Several years ago the Leech Lake band brought in sand to improve the nesting area for the terns. And every year the tribe traps predators like mink, to give the young terns a better chance of survival.

Ironically, the lack of predators on the island is one reason why the cormorants are thriving.

John Ringle says that's just the way it goes in resource management.

"My philosophy is that as mankind utilizes the resource, we have to manage them," he says.

But Ringle says he isn't sure he and other managers know enough to do a good job.

"I think the public is demanding action prior to any conclusive study being conducted," he says.

And that's a big problem for Francie Cuthbert. She teaches bird biology at the University of Minnesota, and she's been researching cormorants for years. Cuthbert says the agencies working together to cut down the cormorant population are using the common tern as an excuse. She says they rely on an arbitrary baseline population number for terns that goes way back to the 1930s.

"The numbers of common terns have fluctuated a lot and dropped significantly since that time, way before cormorants were present," she says. "And they've had very good productivity in the years where the highest numbers of corm were present."

Cuthbert says conservation officials skipped an important part of the management process -- finding out what's actually happening on Leech Lake.

"They're really being driven by complaints from citizens, resort owners who are concerned about local economics," she says. "And they just don't like the birds; they're afraid of the numbers. If we responded to all natural resources conflicts this way, we'd be in a state of chaos."

Cuthbert says even with the cormorants' dramatic come-back since the days of DDT, there still aren't as many as there were a hundred years ago. She sees the problem of cormorants as a conflict between humans and a rival predator. Control advocates say they want to restore a balance on Leech Lake. But Cuthbert says that doesn't necessarily mean killing cormorants.

"The balance would be to somehow increase the numbers of fish," she says. "They've declined primarily from overharvesting."

Cuthbert and other critics say this year's culling may result in fewer cormorants on Leech Lake next year, but it would take a lot more than that to have any effect on the population of cormorants in North America as a whole.

In addition to culling cormorants, the DNR is stocking Leech Lake with walleye for the first time this year. Several agencies are cooperating to conduct more research on what the cormorants are eating. And for the next five years there's a slot limit to protect young walleye from anglers.

That makes resort owners like Larry Jacobson nervous, because he says a lot of anglers don't like slot limits. But at least he's glad someone's doing something.

"The fishery is a business, there's no question about that," he says. "If you want to sustain our economy in this area, you've got to manage the lake."

Workers will continue shooting cormorants occasionally through the summer. Experts say they'll likely have to continue the control effort for at least another year.