July 24, 2006
Are cormorants eating area walleye? Dassel man asks
By Roz Kohls
Harold Mattson of Dassel has watched the walleye fishing in area lakes, Jennie, Collinwood and Washington, deteriorate the last three years. At the same time, he noticed the population of cormorants balloon on the island in Pigeon Lake, south of Dassel.
Is there a correlation, he wondered?
The jury seems to be out for the moment, since local experts do not believe that the walleye population counts are lower than usual, and Sen. Steve Dille has indicated that he was told local cormorants primarily eat bullheads.
However, the idea is intriguing, especially since there is a similar situation near Leech Lake in northern Minnesota, where Mattson heard about a cormorant control program there because the birds were negatively affecting the lake’s walleye population. Leech Lake had 73 nesting pairs of cormorants in 1998 but the population mushroomed to 2,524 nesting pairs in 2004.
Mattson questioned whether the cormorant population at Pigeon Lake also was affecting fishing in Meeker, Wright and McLeod counties.
Cormorants are large, dark-feathered, fish-eating birds with hooked beaks. Their wings are not as oily as other water birds like loons and ducks, so they often are seen spreading their wings to dry in the sun and air.
Mattson first contacted State Sen. Steve Dille, R-Dassel, if duck and goose hunters from the area could shoot cormorants in the same program the U.S. Fish and Wildlife Service uses to control the excess cormorants at Leech Lake. The federal program allows hunters to take about 10 percent of the population.
Dille gathered information from both Lee Pfannmuller of the Minnesota Department of Natural Resources and Gene Jeseritz, assistant area fisheries supervisor, in Hutchinson.
Pfannmuller confirmed that the number of cormorants on Pigeon Lake is growing. In 2002, there were 1,399 nesting pairs. In 2004, there were 1,503 nesting pairs. Pigeon Lake also is a nesting site for white pelicans, blue herons, great egrets and black-crowned night herons’ nests.
“Following the statewide assessment in 2004, it was identified as one of the four most important colonial waterbird nesting sites in the state,” Pfannmuller said in his report.
Even though the number of cormorants is expanding at Pigeon Lake, the walleye surveys done on all 50 lakes in the area every seven to 10 years show no change in the number of fish.
“We haven’t seen the symptoms,” Jeseritz said. “It may in the future. Who knows?”
The changes that Jeseritz has observed in the fish population seem more likely to be the effect of global climate change rather than cormorants. Winter kill, in which a lake freezes so that the fish have no oxygen, for example, has been minimal in the last few years.
The islands in Pigeon Lake might look decimated from a human point of view, but biologically, they are ideal nesting sites. Nesting sites on islands are safer from predators. Also, the more vegetation that is destroyed, the better birds can see if a predator approaches the island, Jeseritz added.
Dille sent a letter to Mattson enclosing the information he received from the DNR. Dille added a note that he had been told the cormorants in this area eat mostly bullheads.
Also, the DNR’s budget is limited so it won’t focus on cormorants at this time, he said.
Mattson noted that he thought hunting the cormorants would be free.
See Mattson’s Letter to the Editor on the Viewpoints page.