By Carol Stiffler
This spring, agents with the Animal Plant and Health Inspection Services (APHIS) will visit Big Manistique Lake’s Gull Island for a permitted lethal reduction of its cormorants. That is to say: a percentage of the adult cormorants on the island will be killed – perhaps even half of them.
That’s very welcome news for a large number of people who believe the cormorants may be dramatically reducing the number of walleye in Big Manistique Lake.
“We’ve certainly heard your concerns,” said Doug Schultz, Lake Huron Basin Coordinator with the Michigan Department of Natural Resources (DNR). “We’re acting on it as quickly and effectively as we can to manage that colony at a level that is biologically acceptable.”
It may surprise some, but Schultz said cormorants actually belong here.
“They’re a native species that belong on the native landscape,” he said.
That said, there are more cormorants on Big Manistique than residents are accustomed to seeing. Schultz said their numbers “really took off” in the early 2000s.
Cormorants are migrators that travel as far north as Canada and as far south as Mexico. During the summer, there have been about 100 cormorant nests on Gull Island in recent years. Each nest is inhabited by a pair of cormorants and produces an average of two fledgling chicks per year. There are no homes or permanent structures on the island.
Finding the balance of how many cormorants Big Manistique Lake can sustain without damaging its walleye fishery may be tricky. APHIS teams – a branch of the United States Department of Agriculture – have only a three-week window to work on culling the flock. That’s the amount of time between when the birds return to the area and when they begin to nest. Once they’re nesting, law dictates that they are protected.
Cormorants are quick learners, Schultz said, and once they figure out what APHIS is up to on the island, the jig will be up. Efforts to reduce cormorant numbers will have to stop until the following spring.
Since cormorants will continue to migrate north from Mexico annually, new pairs may take up residence and build families on Gull Island each year.
Though the birds are native and protected, the Michigan DNR has requested and received a permit from the U.S. Fish and Wildlife Services (FWS) to reduce the number of cormorants on Big Manistique Lake, among others. That permit was issued years ago and was originally going to be enforced last spring. Staffing shortage within APHIS prevented the work from being carried out last year, which disappointed local anglers.
Betsy Pollaski, a Curtis-based realtor and current president of the Portage Anglers Club, has been actively researching the cormorant problem and how civilians can help.
“This was the first and biggest complaint I was fronted with when I joined the Portage Anglers Club,” Pollaski said. “It’s a major problem, and it’s a major problem in a lot of areas. We’re not the only people dealing with this.”
Pollaski has educated herself on the species and the lake and more, and has been in direct communication with the DNR and tribal groups about what civilians can do to drive off cormorants and support the walleye fishery.
Hazing, intentionally harassing the birds without harming them, is legal. Residents around the Big Lake probably recall hearing periodic explosions a couple summers ago when a propane cannon blasted every few minutes to keep the cormorants unsettled. The birds quickly adjusted to the sound and it stopped being effective.
Pollaski would like to see civilians – whether they fish or not – boating to Gull Island to light a brief bonfire, or install wind chimes or whirligigs, and to generally make Gull Island look like a scary place to land.
“These birds come in and try to land in early spring and make our lake their home,” Pollaski said. “The more we habitat it and show this our home, not their home, the fewer chances are that they want to lay a nest.”
The Portage Anglers Club raises money to stock the Manistique Lakes with walleye, planting $20,000 of fish at a time. This summer, they raised money to build walleye “cribs”—triangular structures that are four feet wide, eight feet long, and four feet tall. Built of logs and weighted by cinder blocks, the tee-pee like cribs are laced with hardwood branches to create small spaces for tiny walleye to hide from predators.
The club sank 10 cribs into Big Manistique Lake this summer, sponsored at $250 each, and hopes to sink 10 more next summer.
Efforts like that matter because there is very little weed bed or fallen trees on the shoreline of the lake for young walleye to lurk in. That’s because the lake is so densely surrounded by homes, said John Bauman, fisheries biologist with the DNR. The shoreline has largely been cleared of fallen trees.
Bauman just published a massive report on Big Manistique Lake, detailing as much history and analysis of the lake as was possible. His report is found online at https://bit.ly/BigLakeStudy (case sensitive).
Bauman helped conduct two surveys on the lake during 2024, using electric shocks to briefly stun the walleye so they could be counted and measured. In September, a team of multiple agencies including the DNR shocked the entire perimeter of Big Manistique Lake to study the fish population. They found an average of 2.1 walleye per acre, and estimate that there are 21,604 adult walleye in the 10,000 acre lake.
That’s a healthy number, Bauman said, and is about three times more walleye than were present in the lake 20 years ago.
“We found a good population of adults, but not strong recruitment,” he said. Generations of younger fish were not well represented.
“As natural populations do, they fluctuate,” Bauman said. “Walleye are less in abundance than they were from 2009 to 2014, but I think there’s reason to expect that there will be a big natural year class soon.”
Walleye in Big Manistique Lake tend to have a big hatch about every five to seven years, Bauman said, and we are due for a big season. Called “natural recruitment”, the term refers to new walleye that live an entire year and reach about 7 inches in length. Naturally recruited walleye classes have been small in the lake for five years in a row now.
Cormorants are part of the problem there, but the lake is changing as well, Bauman said. Invasive zebra mussels have taken hold, clearing up the lake’s famously “muddy” water. The temperature is warming slowly. Walleye prefer cooler, murky waters, and this may be contributing to a change in their behavior.
“Big Manistique Lake has always had one of the highest rates of natural reproduction of walleye, and really high catch rates,” Bauman said. “But I do believe anglers’ reports that fish have become difficult to catch. The people that are catching walleye have been there for a long time.”
Public input has played an important role in how cormorants will be managed locally, and Schultz is impressed with local interest and effort taken to support the lake. Having recently transferred to Michigan from a DNR post in Minnesota, he appreciates how active citizens are regarding conservation resource management.
“The cooperative relationships that exist here are irreplaceable,” he said. “We get a lot of very valuable insights from folks who are there every day and have a vested interest.”
The News will continue to follow this story.
About cormorants
A flock of cormorants is called a “gulp”. It may also be called a flight, rookery, or a swim.
Cormorants are medium-large birds, with body weights that can reach 11 pounds and a wingspan that can exceed three feet. They are expert divers and fast swimmers. Diving underwater to catch prey soaks their outer feathers, which do not repel water, and cormorants are often seen standing on land with their wings outstretched to dry off.
