Cormorant controls are paying off
Anglers who has fished the nearshore waters of the upper Great Lakes for a number of years have seen a menace that rose from near extinction to a very troubling population in the 1990s.
This fish-gobbling marauder is the double-crested cormorant, a waterbird that has been blamed for greatly reducing the number of gamefish in the Great Lakes.
Its numbers fell to nearly zero by the 1970s – due mainly to the widespread use of the pesticide DDT, which also greatly reduced the numbers of other fish-eating birds, such as bald eagles.
Following the outlawing of DDT and other harmful chemicals, the cormorant population rose quickly, with the U.S. Fish and Wildlife Service estimating the continental U.S. population at about 2 million by the year 2000.
What did this mean for the aforementioned nearshore anglers on the Great Lakes? They started to see severe negative impacts on fish numbers, including just about every species fishermen pursue on lakes Superior, Michigan and Huron.
This occurred because cormorants are voracious fish eaters, estimated to consume about a pound a day each. They dive to varying depths to gobble up loads of smaller fish, such as young that have hatched naturally as well as those that were planted. Planted fish were hit especially hard because they would be concentrated at release sites.
There was a loud uproar for action to be taken to control the exploding cormorant population, and state and federal agencies responded. It didn’t happen overnight though, seeing that cormorants are federally protected birds, being added in 1972 to the list of species protected under the 1918 Migratory Bird Treaty Act, according to the USFWS.
However, a federal depredation order was issued in 2003 that authorized state, native American tribes and the federal government to manage cormorant populations.
In a report released last week, the Michigan Department of Natural Resources outlined how successful those efforts have been.
The USFWS began oiling eggs so they wouldn’t hatch and killing cormorants on Les Cheneaux Islands off the Upper Peninsula in Lake Huron, where cormorant numbers were extremely high.
Similar efforts spread across the upper Great Lakes, including at Thunder Bay near Alpena, Beaver Island and Ludington downstate and in the Bays de Noc off of Delta County, according to the DNR report, which said as many as 10,000 birds per year for the past several years were killed.
“Subsequently, cormorant nesting populations have been reduced anywhere from 54 percent to 94 percent at peak nesting counts at these locations,” the report states. “In colonies where management efforts have been conducted, the estimated cormorant nest count in Michigan waters has gone from more than 23,000 in 2007 to less than 10,000 in 2013.”
In addition, the USFWS – which oversees efforts by states, tribes and volunteers – has directed harassment programs by volunteers on inland lakes and Great Lakes bays during spring migration. Volunteers also help drive cormorants away from fish planting sites on the great Lakes.
“It’s difficult to evaluate the effects of cormorant management and its relationship to sport-fish populations due to constantly changing food-web dynamics, including the establishment of invasive species throughout the Great Lakes,” DNR fisheries biologist Steve Scott said in the report. “Fisheries surveys have shown an increase in sport-fish populations during the same period cormorant populations were declining in areas where activities have been conducted. We are seeing some very encouraging results in fisheries at several locations, and anglers are reporting improvements.
“We are very pleased with the progress we are making through our partnership with Wildlife Services.”
Anglers along the areas of the Great Lakes where cormorant control efforts have been successful should be please with the efforts, as well, and we can only hope wise cormorant management will continue well into the future.
Editor’s note: City Editor Dave Schneider can be contacted at 906-228-2500, ext. 270.