Cormorants corner trouble at Lake Waconia

Double-crested cormorants have been shot at Lake Waconia for the past four years, part of an ongoing effort to limit damage to a private island. But now they're under the gun on another front.

As described by Waconia Mayor Jim Nash, fishing in the lake isn't what is used to be. The business that fishermen bring to town is down, posing an economic hardship. The problem, according to Nash, is the cormorants that nest on an island in the lake. There is suspicion that the birds are eating game fish, but surely, he believes, they are eating the small fish that game fish would eat. Thus deprived, game fish exist in smaller numbers.

Solution: Get rid of the birds.

Shooting the birds was already the solution to another problem: Cormorants, herons and egrets nesting on the island are killing vegetation with their waste. The owner of the island would like to preserve its natural beauty, and the man has a right to ask that his property be protected. (No one is asking that herons and egrets be shot.)

To try to lessen damage to the island, the U.S. Fish and Wildlife Service issued depredation permits, approved by the Minnesota Department of Natural Resources, resulting in the shooting of about 1,400 cormorants to date. This year, 329 birds were killed, leaving 74 pairs.

But there's still the perceived fishing problem.

How bad is it? In August 2010, the DNR department of fisheries came to Lake Waconia for a biannual survey of the fish populations there. Walleye abundance was described in the survey summary as average, weight above average. Northern pike numbers were high compared to historic averages for the lake. More largemouth bass came up in the test nets than in the past. Abundance and weight of muskies were the highest ever recorded for the lake. Crappies were small but above average in number. Bluegill abundance was at a level not seen since 2002.

If birds are creating a food shortage that is affecting fishing, why are walleyes larger than average, pike numbers high, muskies at record levels? Those fish must be eating something.

So, why are cormorants being blamed when fish populations appear to be doing very well?

Cormorants are easy to blame. They're big, black, visible birds that eat fish. They've been treated this way around the world for hundreds of years. People hate them, according to Francesca Cuthbert, a colonial waterbird expert at the University of Minnesota.

Studies of the relationship of cormorant feeding habits to fish populations at other lakes show no conflict, but those studies make no difference. In Waconia's case, no difference means asking Congress to pass a bill making it easier to get permission to shoot the birds. The bill is co-authored by Minnesota Reps. John Kline and Colin Peterson, and it has a dozen co-sponsors from a range of states.

There appears to be no lack of keeper fish in the lake. Are fishing revenues in Waconia down because of cormorants, or might there be other reasons?

The weather, maybe? The fishing season begins in mid-May. From that point through September we had 16 days when the temp exceeded 90 degrees and 14 days when rainfall was near half an inch or higher. How about the economy? Maybe some fishermen find themselves pinched for recreational dollars. Maybe it's not fewer fish. Maybe it's fewer fishermen.

Whatever the reasons, cormorants are taking the rap in Waconia.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com. Join his conversation about birds at www.startribune.com/wingnut.