Cormorants take a legal hit
Written by Detroit Free Press - Puckstop   
Thursday, 05 May 2005 10:24
Aerial surveys at the Les Cheneaux Islands in northern Lake Huron last summer found less foraging pressure by cormorants, the black, goose-sized diving birds that each eat a pound of fish a day.

The decrease followed an experiment by the U.S. Department of Agriculture and the state Department of Natural Resources to reduce cormorant numbers in selected areas. Some adult birds were killed, and thousands of eggs in nests were oiled to prevent them from hatching.

Cormorant numbers had increased sharply on the Great Lakes in the past 10 years, and the fish population dropped.

Early indications are that the government experiment resulted in an improvement in fishing last summer, said Peter Butchko, state director of a U.S. Agriculture office in charge of controlling wildlife that causes agricultural or environmental damage.

Butchko said scientists need to monitor the program for a few more years to see: "Are we making progress, or are we only making people feel good? But the program looks like it started working right away. It seems to support our premise that if we reduce the number of birds nesting in Les Cheneaux, we can reduce the number of birds foraging in Les Cheneaux."

By conservative estimates, roughly 600,000 cormorants were on the Great Lakes in 2000, the U.S. Fish and Wildlife Service reported. That contrasts with the 200 found on the lakes in the 1970s, when DDT and other pesticides had nearly eliminated them.

The cormorant population increased at about 7 percent a year through the 1990s, though the rate dipped a couple of years ago, perhaps because alewife numbers have declined.

Still, there might be about three-quarters of a million of the birds on the lakes today.

A New York study on Lake Ontario several years ago determined that 100,000 birds ate about 85 million fish during a summer. Most of those fish were bait-fish species, but about 1.3 million were smallmouth bass, which raised the ire of anglers and charter boat captains.

In the Les Cheneaux Islands just off the eastern Upper Peninsula, about 25,000 to 30,000 birds compete daily with sportfishermen in an area where the primary catch is perch -- a fish that is the ideal size for a cormorant.

While no studies have shown how many of the fish eaten by cormorants are perch, anglers say it is no accident that perch numbers have declined as the cormorant population has grown.

Figures since 1969 show the death rate of adult perch was high even when fishing pressure decreased, Butchko said.

The smoking gun appeared to have webbed feet, a hooked black beak and the ability to dive to 200 feet deep, so the state and federal wildlife agencies completed an environmental impact statement that would allow them to reduce cormorant numbers in an effort to rebuild the fishery.

As expected, animals rights groups sued in an effort to block that plan, but in February 2004, a federal court gave biologists the right to go ahead under U.S. Fish and Wildlife Service supervision.

By killing fewer than 1,000 birds and oiling the eggs in thousands of nests, the Agriculture Department achieved a 99-percent reduction in reproduction in the three test areas in the islands.

The Fish and Wildlife Service permit doesn't allow private individuals to kill birds, despite cries from anglers for a hunting season. The permit allows state and federal workers to use methods that include nest destruction, egg oiling, shooting and cervical dislocation, a bureaucratic euphemism for wringing a bird's neck.

Another step will be to put radio transmitters on cormorants to monitor their daily activities, Butchko said.

"We know that perch numbers in Les Cheneaux increased as cormorant numbers decreased" last year, Butchko said. "Previously, perch numbers dropped dramatically as cormorant numbers increased. But I don't know how much credit we can take for it."

Drummond Island also has a cormorant problem, but it's different from the problem in the Les Cheneaux. Few cormorants nest at Drummond, but large numbers show up for three weeks during the spring migration, and their arrival coincides with the movement of perch and walleyes into spawning areas near the island.

On any given day, 1,000 to 1,500 cormorants feed on those fish, "but killing a lot of birds there wasn't going to do much," Butchko said. "We had to get them out of there."

So biologists used fireworks and boats to harass the cormorants, shot 293 and soon saw a 98 percent reduction in the number hanging around the island.

Butchko said the program probably prevented 9,000 pounds of perch from disappearing down the gullets of cormorants, but he acknowledged that it also might have chased the cormorants away from Drummond only to make them someone else's problem.

The Canadian Ministry of Natural Resources is doing a study of cormorant predation on fish in Lake Huron, where it estimates there are 20,000 nesting pairs. One angler said that estimate is ridiculously low.

"The ministry doesn't want to admit the extent of the problem," said Gary Walker of London, Ontario, who said cormorant predation is especially heavy in popular sportfishing waters in Georgian Bay. "The city of Toronto even holds a 'Welcome Back, Cormorants' day every April. The ministry doesn't want to have to tell people that it's time to start killing some of those birds."

 
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