Perch on upswing as birds decline
Written by Detroit Free Press   
Sunday, 28 January 2007 14:11

The once-famous perch fishing around Les Cheneaux Islands has come back strong, locals say. Federal and state biologists cautiously agree that the reason is three seasons of killing cormorants - the big, black diving birds that feasted on perch - and oiling cormorant eggs to prevent them from hatching.

Last summer, there were about 3,500 fewer cormorant nests in Les Cheneaux than in 2003. Researchers figure that equated to at least 1 million pounds of perch, smallmouth bass and other inshore species that didn't wind up as cormorant food.

Les Cheneaux once was one of the best perch fisheries in the state. But perch numbers had declined dramatically by the mid-1990s as cormorants nesting on the islands increased, anglers said.

At the peak in 2003, the two-dozen Les Cheneaux Islands between Hessel and Cedarville in northern Lake Huron hosted 5,500 double-crested cormorant nests.

Pete Butchko, director of the U.S. Department of Agriculture wildlife services office in Lansing, said biologists figure that for every seven cormorant nests, a ton of fish is required to raise the young. And for every nesting pair there were two more grown but sexually immature birds, which eat about 2 pounds of fish each per day. That means about 22,000 cormorants living around the islands in the summer of 2003 wolfed down 6 million to 10 million fish, including huge numbers of perch that were a mainstay of the local tourist economy.

But over three years, researchers shot 4,448 cormorants and oiled the eggs in thousands of nests, and the number of nests declined almost 65% by last summer.

Testing a theory

The situation in Les Cheneaux presented an opportunity to learn whether reducing cormorant numbers would result in the recovery of the perch fishery.

Mark Engle, who owns Les Cheneaux Landing Lodge with his wife, Esther, said the answer appears to be yes, and he is surprised by how quickly the perch rebounded.

"If you'd asked me five years ago, I'd have been pretty pessimistic on how long it would take to come back," he said. "But I have to say that the biologists were right when they said perch could come back quickly. We had some good perch fishing last summer and fall. Guys who used to fish here years ago came back and were able to go to their old spots. And it wasn't just a lot of fish, they got some big ones, too."

Gil Peacock drove to Cedarville for a weekend of ice fishing because there was no safe ice near his home in Mt. Pleasant.

"I used to fish here 10, 15 years ago, and a friend who comes up every summer told me the perch were pretty good again," Peacock said. "Three of us came up, and it's been good. You had to weed out a lot of small ones, but there are enough nice perch, 10-inchers, to make it worth coming."

Researchers agree with the anglers, if more cautiously. Steve Scott, a Department of Natural Resources biologist in Newberry, said, "We seem to be seeing a turnaround in the perch fishery. It looks like the result of cormorant control, but we don't have the smoking gun yet."

How birds got big

Cormorants, the hooked-beak birds, were rare on the Great Lakes as recently as the 1970s, before their numbers grew into hundreds of thousands that nest on the Great Lakes today.

Scott and Butchko said many biologists believe that cormorants were able to increase so dramatically because the Welland Canal between lakes Ontario and Erie opened the four upper lakes to alewives, an exotic invader from the Atlantic Ocean. Alewives took over the four lower lakes by the 1960s, creating an ideal prey base for a bird that hunts 6-10 inch fish underwater and can dive deeper than 100 feet.

Scott said: "I think the arrival of the alewives allowed the cormorant population to grow on the Great Lakes. Then (fish farms) proliferated all over the South, and we know they helped cormorants survive the winters in bigger numbers and better health. I suspect our cormorant problem is the result of several factors."

Birds aren't only culprits


Dave Fielder, a Michigan DNR biologist at the Alpena Lake Huron research station, has been analyzing fisheries data for the researchers running the cormorant experiment at Les Cheneaux.

While the test will run two more years, Fielder said, "It's my belief that cormorants were the principal force behind the perch decline. We also have to look at other factors, including the fact that we've had some big perch year classes produced. But we've seen big year classes before that disappeared in the presence of cormorants."

The state has appropriated $150,000 to fund Les Cheneaux cormorant research next year, but Congress hasn't passed a bill to match those funds. Butchko said the program is to last two more years, at the end of which "I think we will all agree that cormorants have been reduced to an acceptable level. Then I think we can maintain those numbers with a maintenance program that involves shooting a few birds one year and oiling some nests the next."

Fielder cautioned that the cormorant data from Les Cheneaux might not explain perch declines in other areas, and he added that fishermen might bear some blame in Les Cheneaux.

"Some people would like to blame it all on cormorants," Fielder said, "but there's some evidence that (overfishing by anglers) has played a role in fluctuating perch numbers. That's why we put a 7-inch minimum in (Les Cheneaux), and we may need to look at tighter regulations, like a smaller limit."
 
You need to login or register to post comments.
Discuss...