Anglers around the Great Lakes are eager for a summer of fishing. Everyone wants to catch the big one. But they’re getting some competition. It comes in the form of the double-crested cormorant. The big black birds with long necks are fish eaters. Cormorants were nearly wiped out by the now-banned pesticide, DDT, in the 1970’s. But now cormorants are back in big numbers. Some anglers feel there are too many cormorants now. And they say the birds are eating too many fish. The Great Lakes Radio Consortium’s Stephanie Hemphill reports on one experimental effort to control cormorants:
Anglers around the Great Lakes are eager for a summer of fishing. Everyone wants to
catch the big one, but they’re getting some competition. It comes in the form of the
double-crested cormorant. The big black birds with long necks are fish eaters.
Cormorants were nearly wiped out by the now-banned pesticide, DDT, in the 1970’s. But
now cormorants are back in big numbers. Some anglers feel there are too many
cormorants now, and they say the birds are eating too many fish. The Great Lakes Radio
Consortium’s Stephanie Hemphill reports on one experimental effort to control
(sound of waves)
Robin Whaley often fishes here on Knife River. It’s the biggest spawning ground for
rainbow trout on the north shore of Lake Superior. But today she’s watching the
cormorants on Knife Island, a quarter-mile offshore.
The cormorant population is booming. About a hundred cormorants lived on the island
“I guess they’re just coming up into this area in the last few years and becoming a
problem, for degrading habitat and for eating little fish.”
Cormorants are native to this area, but they haven’t been around much in the last few
decades, because of poisoning from the pesticide DDT.
The Minnesota Department of Natural Resources stocks rainbow trout here. This year
they put 40,000 young fish into the river. Anglers like Robin Whaley hope the little fish
will grow big enough for them to catch someday.
The little fish face a lot of predators and hazards and the cormorants are one more threat.
Some people would like to reduce that threat. It’s illegal to kill cormorants. They’re
protected by law because they’re a migratory bird.
But a new federal rule says if they’re threatening a resource, people can fight back in a
Bill Paul runs the Agriculture Department’s Wildlife Services Program in Minnesota. He
sent workers onto Knife Island to try to keep the cormorants from nesting. Their methods
are experimental – but they’re pretty basic.
“We put up some flapping tarps in wind, a couple of yellow raincoat scarecrows, we also
put up ten flashing highway barricade lights, we also have a light siren device out there
that goes during the night.”
The workers also used special firecrackers shot by guns at passing birds to scare them
They did this for two weeks during the cormorants’ nesting season. Bill Paul says even
with all that noise and commotion it wasn’t easy to scare them away.
“They seem to be fairly smart birds and real persistent at coming back to Knife Island.
So we’re uncertain yet whether our activities are actually going to keep them off there
As part of their study, researchers had permission to kill 25 cormorants to find out what
they’d been eating. They wanted to see how much of a threat the birds were to game fish
like the rainbow trout.
They found fish in the cormorants’ stomachs all right. But not the kind most people like
to catch and eat.
Don Schreiner supervises the Lake Superior fishery for the Minnesota DNR. He says
he’d need more than just a few samples to really know what the birds are eating.
“My guess is that cormorants are opportunists and if there’s a small silver fish out there
and he’s just hanging out and the cormorant has that available to eat, he’ll eat it. The
question becomes, is this a significant part of the population that they’re consuming, or
Despite the concerns of some anglers, researchers have been studying cormorants for
years, and so far they haven’t been able to prove the birds are harming wild fish
John Pastor is an ecologist at the University of Minnesota Duluth. He says the study at
Knife River won’t prove anything useful either.
He says it ignores the bigger picture. Pastor says you can’t just look at one predator and
come to any firm conclusions. There could be lots of reasons why there aren’t many
steelhead, or rainbow trout.
“Changes in land use. All the adult steelhead out there eating the young of the year
steelhead. Maybe it’s some pollutant in the lake. You never know. But it’s easy to fix on
the predator as the problem, because people see a cormorant dive down and come up with
a fish, and they say to themselves, I could have caught that fish.”
Pastor says even if the cormorants are eating lots of young rainbow trout, it doesn’t
necessarily mean the birds are hurting the overall trout population.
And even for an angler like Robin Whaley, the concern about the trout is mixed with a
feeling of respect for the cormorant.
“I admire the bird very much, but human beings, we’re in the business of controlling
habitats and populations, and this is just another case of that.”
For many anglers, the ultimate question in this competition between predators is simple.
It’s about who gets the trout – cormorants or humans.
For the Great Lakes Radio Consortium, I’m Stephanie Hemphill.