The once-renowned bass and perch fisheries here are just a memory, gobbled up by tens of thousands of big, black diving birds that can eat more than their own weight in fish in a week.

Sport and commercial fishermen and tourism interests want the state and federal governments to cut the number of double-crested cormorants around the Beaver Island group by half, raising the ire of bird lovers and animal-rights activists who say the cormorants aren't at the root of the problem.

The dispute is yet another example of how things we did to damage the Great Lakes in the past can come back to cause problems that we never anticipated.

The islands of this Lake Michigan archipelago 30 miles offshore from Charlevoix host what may be the densest concentration of the big, black diving birds on the continent, an estimated 50,000 that eat about 9 million pounds of fish from the surrounding waters from spring through fall.

Jeff Powers, the island veterinarian, said, "We once had a world class smallmouth fishery here. Now you can fish all day without catching one. We still have good numbers of summer tourists, the people who come to lie on the beach, but spring and fall tourism was almost all fishermen, and they're gone."

Cormorants are protected under migratory bird treaties and cannot be killed without permission from the U.S. Fish and Wildlife Service. Animal rights activists and bird lovers have made killing cormorants a cause célèbre, and the anglers say the DNR and FWS have knuckled under to pro-cormorant groups while ignoring the precepts of good wildlife management.

Larry Myers of Houghton Lake has been leading a crusade to reduce Michigan's cormorant population and accuses the federal and state governments of using inaccurate and misleading information.

"The DNR and the FWS say they don't find many bass or perch in the stomachs of cormorants around Beaver Island. That's because there aren't many bass or perch left. The cormorants got them years ago," Myers said. "The DNR doesn't talk about a study in 1999 that showed cormorants were having a major impact on smallmouths at Beaver Island. Now they're eating crayfish and round gobies, because that's about all that's left."

In addition to killing fish, cormorants have very acidic feces that wipe out vegetation on the islands where they nest, a handy evolutionary adaptation if you're a bird that nests on bare ground.

About 20 years ago Hat Island, a tiny lump of sand a few miles north of Beaver Island, had a rich covering of trees and bushes. Flying over Hat today, the scene looks like a Hollywood version of the aftermath of a nuclear war, the trees nearly all dead skeletons, the bushes withered stumps and the bare ground covered with thousands of ground-nesting black birds.

To local tourism interests, Hat Island, with its roughly 8,000 nests, is the festering center of a biological infection, but the U.S. Fish and Wildlife Service refuses to allow the USDA to kill adult birds or oil eggs there, citing the risk of damage to other ground-nesting species, like terns.

A major issue is whether cormorants, common on the seacoasts, were indigenous on the Great Lakes before white settlement. Environment Canada found the first record of cormorants nesting on the lakes was 1913, birds that apparently migrated to western Lake Superior from Lake of the Woods in Manitoba. By 1946, they had reached Lake Ontario.

Biologists say that there were about 900 nesting pairs on the lakes in the 1950s, which dropped to 125 pairs by 1973, largely the result of DDT pollution. But by 1997 the Great Lakes population had exploded to about 240,000, and by 2006 it may have reached 500,000.

The population explosion probably was made possible by the elimination of DDT and the reduction of large predatory fish, decreasing competition for the smaller fish available to the birds.

The arrival of zebra mussels in the 1980s caused a great increase in water clarity, which helped sight-feeders like cormorants catch food (they have been caught in nets as deep as 140 feet.)

People who oppose killing cormorants claim they are indigenous to the Great Lakes and disappeared because of hunting and DDT. The problem with that argument is that there was no DDT before 1913, and while ancient Indian garbage dumps excavated by archaeologists contain the bones of everything from turkeys to eagles, there are no cormorant bones.

Jim Dexter, a supervisor in the DNR's fisheries division, said cormorants are only one factor in the sport fish decline in the Beaver Island group and added that "fishermen want to blame cormorants for everything that's gone wrong. Beaver Island lost the bass fishing 30 or 40 years ago," partly because anglers took too many bass, he said.

But Myers said that the experience of Les Cheneaux Islands is proof that the birds are the primary culprits.

"Five years ago the U.S. Department of Agriculture Animal Control people went in there and started oiling eggs and killing adult birds. They reduced the number of cormorants around Cedarville from 6,000 about 1,500, and in three years the perch fishery improved 42%," he said.

For the full article, see Eric Sharp, Are cormorants ruining fishing?", Detroit Free Press, June 15, 2008.