The U.S. Fish and Wildlife Service is about to take its first major step to regain the authority to kill problematic cormorants via depredation permits, a move that could reopen site-specific shooting of the aquatic birds in Minnesota and other Great Lakes states by next spring.
It's been more than a year since a federal judge terminated the culling of double-crested cormorants across the country. Wildlife officials in many states have been yearning for the return of the control measure — even if on a limited basis. Minnesota is one of 24 states affected by the ruling.
"We needed to take a closer look at the effects [on cormorants]," said Tom Cooper, regional chief of the Fish and Wildlife Service's Migratory Bird Program in Bloomington.
Cooper said the agency will publish a draft environmental assessment within weeks for a plan that would provide more accountability and a new, big-picture look at cormorant population effects before fish farmers, lakeshore property owners, bait suppliers and others can receive authority to kill cormorants. Those requests are considered only when fireworks and other nonlethal control measures fail to halt damage caused by the gangly birds, Cooper stressed.
Cooper said the first step in regaining permitting authority deals with depredation related to human health and safety, damage to aquaculture, damage to private property and concern for nesting species crowded out by cormorants.
Not addressed in the current campaign but lurking in the background is a second type of depredation authority to kill the fish-eating birds on lakes where they are believed to be hurting fish populations. That authority, too, was nixed last spring in the ruling by U.S. District Judge John D. Bates of Washington, D.C. He said the agency needed a stronger biological foundation before it could resume handing out the two types of culling permits.
Natural calling
The judge sided with environmental groups who said shooting cormorants for eating fish is like shooting buffalo for eating grass. The goose-sized birds are native to North America and shared the same decline as American bald eagles when the farm pesticide DDT almost wiped them out in the 1970s.
University of Minnesota population studies estimated only 600 nesting pairs of cormorants in the Great Lakes area in 1977. Their numbers surged in the region to a peak of 112,600 nests in 2005, giving rise to nuisance complaints in Minnesota and elsewhere from anglers, resort owners, tourism officials, minnow pond operators and others. Alleged cormorant damage has been studied on at least three big Minnesota walleye lakes — Mille Lacs, Vermilion and Leech — but the birds have been hunted by permitted sharpshooters on many other water bodies, including Lake Waconia, Wells Lake in Rice County and lakes in the Breezy Point area.
Cooper said the agency is first focusing on restoring permit authority to deal with tangible damage reports. The broader "public resource" depredation permit needed for stopping cormorants from feeding on free-swimming perch, walleye and other fish requires more complex justification.
"Sometimes it's a real problem, sometimes it's not," Cooper said. "We want good science backing up the decisions we make."
For now, Minnesota lake property owners, bait dealers and some ecologists are looking forward to the possible return of permit authority to attack cormorants on sites where they are causing damage to other nesting birds, minnow stocks, trees and other vegetation on lakes.
"We're trying to get back more tools to control them," Cooper said.
From 2004 to early 2016, for instance, Minnesota killed 19,200 cormorants on aquaculture depredation permits. Those killing permits primarily went to bait dealers whose minnow ponds were hit by colonies of the black-feathered birds. Since 2011, all cormorant control permits were issued in a period of relative statewide population stability. According to the most recent scientific estimate (2015), the state is home to 15,421 nesting pairs.
Destructive colonies
Gary Nohrenberg, state director of the United States Department of Agriculture's Wildlife Services — the agency often tasked with controlling cormorants — said he's seen many other cases where colonies of the birds have destroyed trees and other wildlife habitat around lakes. He said Wildlife Services is hoping to resume its cormorant work by next spring in Minnesota and other Great Lakes states if the judge accepts the plan being submitted by the Fish and Wildlife Service.
The method for permitting would be changed to consider cormorant losses on a regional basis, not just site by site as in the past, Nohrenberg said.
Cooper said the only killing of cormorants in Minnesota aimed directly at protecting free-swimming fish has been at Leech Lake and Lake Vermilion.
Biologist Steve Mortensen, director of Fish, Wildlife and Plant Resources for the Leech Lake Band of Ojibwe, said state and tribal natural resource managers might have sought to kill more cormorants on Leech Lake last year and this year if the culling ban hadn't been in effect. He looks forward to the return of permitting, even if the new application process requires more environmental assessment work.
"It would certainly give us more flexibility," Mortensen said.
He admitted it's not easy to tell if colonies of fish-eating cormorants make a given lake less productive for game fish — especially when a lake's ecology is changing because of aquatic invasive species or other factors. Each bird eats about one pound of fish per day. Their preference is for slow-moving, schooling fish in the 1- to 4-inch range.
On Leech, the cormorants peaked in 2004 with a population of 10,000. Anglers and local tourism officials alleged an adverse effect on walleyes and forage fish, and state fisheries managers cited a possible link to the low rate of walleyes developing to catchable sizes.
In recent years, after a revival in Leech Lake walleye numbers, annual passes for shooting the birds have been required to sustain the management goal of 500 nesting birds. In some years, that has required killing as many as 1,700 adult cormorants.
Mortenson said the shooting continued this year under a rare type of permit that allows cormorants to be killed for scientific purposes. The 700 cormorants shot over Leech Lake and tribal lands this spring and summer were frozen and studied for diet details.
"Anything that tends to compete with us for food is a species of concern," Mortenson said.
