A popular fish might be making a comeback in the upper Great Lakes. Yellow perch were once a favorite catch for sport and commercial fishermen, but their populations crashed in the 1990’s. Biologists say new surveys in Lakes Huron and Michigan have found huge numbers of young perch. The GLRC’s Peter Payette reports:
A popular fish might be making a comeback in the upper Great Lakes.
Yellow Perch were once a favorite catch for sport and commercial
fishermen, but their populations crashed in the 1990’s. Biologists say
new surveys in Lakes Huron and Michigan have found huge numbers of
young perch. The GLRC’s Peter Payette reports:
A survey of Lake Michigan found more perch were born last year than in
the best years on record. Two or three times as many.
Recent studies of perch in Lake Huron’s Saginaw Bay have shown
similar results. It’s not clear why fish numbers would suddenly
skyrocket. Weather is believed to be one factor.
Dave Fielder is a biologist with the Michigan DNR. He says perch in
Lake Huron have also benefited from the decline of alewives, which are
an invasive species.
“We’ve known for a long time that alewives are formidable predators and
competitors on newly hatched yellow perch fry.”
Fielder says most of the newborn perch are not surviving so the adult
population in Saginaw Bay has not grown. He says it may be too many
perch have been born and there’s not enough food for them all.
As deer populations increase, the amount of vegetation they consume also increases. Included in their diet is the endangered wild ginseng. (Photo by Lester Graham)
Researchers say deer populations are threatening wild ginseng. They say the therapeutic herb could disappear from the American landscape within the next century. The Great Lakes Radio Consortium’s Shamane Mills has more:
Researchers say deer populations are threatening wild ginseng.
They say the therapeutic herb could disappear from the American landscape
within the next century. The Great Lakes Radio Consortium’s Shamane
Mills has more:
Ginseng is a wild herb believed to boost energy and improve
concentration. The plant inhabits eastern deciduous forests from Maine to
James McGraw is a biologist at West Virginia University. He studied the
health of wild ginseng plants over the course of four years, and published his
findings in the journal Science. He found that increasing deer
populations threaten to eventually wipe out the plant.
“What we found was that populations were depressed because affects
of browsing. They weren’t reproducing; plants would begin to die and they
weren’t recruiting new plants into the population.”
McGraw says maintaining the wild herb is not only important for
ecological reasons. It’s also important to people who depend on it for
income; wild ginseng roots sell for hundreds of dollars a pound.
To control the deer population, McGraw suggests a change in hunting regulations or introducing more deer predators.
A mallard duck hen sitting on her eggs in a strip mall tree planter in Ann Arbor, Michigan. Ducks Unlimited researchers have found that recent declines in duck populations are partly due to a lack of corridors between grasslands where ducks nest and wetlands where they thrive. (Photo by Rebecca Williams)
When this mallard hen's ducklings hatch, they'll have to cross a parking lot and busy intersections to get to water. (Photo by Arthur
Another view from the nest. (Photo by Rebecca Williams)
Researchers with the hunters’ conservation group Ducks Unlimited are reporting they’ve found some of the reasons the duck reproduction rate is falling in the Great Lakes region. The Great Lakes Radio Consortium’s Lester Graham reports:
Researchers with the hunters’ conservation group Ducks Unlimited are reporting they’ve
found some of the reasons the duck reproduction rate is falling. The Great Lakes Radio
Consortium’s Lester Graham reports:
(sound of birds, a duck quacking and a truck door slamming)
YERKES: “Load in.”
Two years ago, we went out in the field with biologist Tina Yerkes and other Ducks
YERKES: “Every day these guys go out and they track the birds and that’s basically how
we figure out what they’re doing. ”
(sound of newly hatched ducklings peeping with hen hissing)
At the time, they were tracking mallard hens, watching them nest, and watching them as
they moved their ducklings from the nests in the grass to nearby wetlands and lakes.
After three years of study, they found some of the reasons duck reproduction rates are
down. We recently had a chance to sit down and talk with Tina Yerkes about the study.
She says, surprisingly, they found that egg production and nesting are good, despite nests
being destroyed by mowers and predators eating the eggs.
TY: “The problem is duckling survival. We have very poor duckling survival in this
area. And, that leads us to believe that we need to alter habitat programs to actually start
doing more wetlands work.”
LG: “So, what’s happening is the ducks are able to nest, they’re able to hatch out the
ducklings, but then when they move from the grasslands where the nesting is to the
wetlands where the ducks feed, they grow, they’re not surviving. What’s killing them?”
TY: “What we’re seeing is that hens, once they hatch their young, they move right after
the first day into the first wetland and it’s a dangerous journey. Basically, because our
habitat is so fragmented that they’re moving these ducklings through non-grassed areas,
across parking lots, roads. It’s dangerous. And, a lot of the ducklings either die from
exhaustion or predators kill them on the way. A lot of avian predators get them at that
LG: “So, we’re talking about hawks and not so much domestic animals like cats and
TY: “Ah, cats are a problem, yeah. It’s hard to document exactly what is getting them,
but feral cats and domestic cats are a problem. Hawks and jays, sometimes…”
LG: “Blue jays?”
TY: “Blue jays can be mean, yeah. But, it’s interesting to note that if you put those
corridors back between nesting sites and wetlands, it’ll be a much safer journey for
LG: “So, what are you proposing?”
TY: “I would look more away from urban areas where those infrastructures are already
intact. We would not certainly expect anybody to tear that type of stuff up. But, outside
the cities and urban areas there are lots of opportunities to look at areas where there is
grass existing or wetlands existing and then piece the habitat back together where we
LG: “There are places, for instance in Chicago, where they’re working to do exactly that.
Do you see that kind of effort in most of the states you studied?”
TY: “Yes, actually we do. Some states like – Chicago’s a very good example. A very
strong park system not only throughout the city, but out in the suburbs as well and we do
see that in a lot of different places. That’s a positive thing.”
LG: “Where are the worst places for duckling survival?”
TY: “The worst duckling survival was the site that you were at two years ago in Port
Clinton, Ohio. And, if you think about what that habitat looks like, what you have is a
few patches of grass and an area that’s heavily agriculturally based, but all the wetlands
have been ditched and drained so that when a bird has to move from an area where it
nested to get to a nice, safe wetland habitat, they have to make a substantial move across
a lot of open fields that don’t have a lot of cover on them. So, here you’re looking at
maybe piecing cover back between the wetland areas and still being able to maintain farm
operations at the same time.”
LG: “What can farmers do to help duck survival?”
TY: “Oh, let’s see. Leave some patches of grass along the fields, especially if they have
wetlands in their fields. Leave a nice margin around the wetland, a nice vegetative
margin around the wetland because the ducks will nest right in that edge as well. Then
they don’t have to move very far to take the ducklings to a nice food source and a nice
LG: “Now, this is not just about making sure that mallard ducks reproduce. What’s this
going to mean for the ecosystem as a whole?”
TY: “Every time we replace a wetland or replace grass on the landscape, we’re
improving the water quality because those types of habitats remove nutrients and
sedimentation from runoff. So, there’s all kinds of benefits. There are benefits to any
other species that depends on grasslands to nest in or wetlands to either nest in or even
for migratory birds. So there’s just a suite of benefits beyond ducks.”
Tina Yerkes is a biologist with Ducks Unlimited. She says the group will be working
with states to develop programs to encourage development of corridors between the
grasslands where the ducks nest and the wetlands where they thrive.
For the Great Lakes Radio Consortium, I’m Lester Graham.
For decades, aquatic invaders have been plaguing the Great Lakes. They’ve changed the way the ecosystems work and affected the balance of life in the lakes. Most of them didn’t just wander in. They hitchhiked a ride into the Lakes in the ballast water of ships from across the Atlantic. The Great Lakes Radio Consortium’s Carolyn Gramling reports… now the combination of these invasive species is causing changes that concern scientists:
For decades, aquatic invaders have been plaguing the Great Lakes. They’ve changed the way the
ecosystems work and affected the balance of life in the lakes. Most of them didn’t just wander in.
They’ve hitchhiked a ride into the Lakes in the ballast water of ships from across the Atlantic. The
Great Lakes Radio Consortium’s Carolyn Gramling reports…now the combination of these invasive
species is causing changes that concern scientists:
Zebra mussels were one of those species that hitched a ride in the ballast of a ship. They first
appeared in the Lakes in the mid-1980s. Zebras and their cousins the quagga mussels compete for
food needed by aquatic animals native to the lakes.
Researchers say now these mussels are part of another problem. They’re changing the food web.
The food web is made up of organisms that feed on each other. Usually it’s a chain of small, even
microscopic species that are food for ever larger species. Zebra mussels are near the bottom. For
their food, they filter large volumes of water containing contaminant-laden algae and sediment. In
the process they ingest PCBs and other toxins.
Gene Kim is a researcher in the Ohio State University’s Aquatic Ecology Laboratory. He says that
zebra mussels and a non-native fish called the round goby have helped to form a new food chain
within Lake Erie – a chain that can connect harmful chemicals buried in lake mud to humans.
“A lot of the exotic species, these alien species, have incorporated themselves into the Lake Erie
food web, and there’s a lot of ramifications, in terms of, will they change the cycling of historical
contaminants that right now are in the sediments, but they could be redirected back into sport fish
and eventually, humans.”
Zebra mussels have few natural predators in North America, and they reproduce rapidly. As a
result, they’ve been wiping out native mussels and clogging up water intake pipes in the lake. So
the arrival of the round goby, which likes to eat zebra mussels, would seem to be good news.
Instead, it has proven to be a double-edged sword.
Roy Stein is a professor in Ohio State’s Aquatic Ecology Laboratory. He says the PCBs and other
contaminants, once held captive in the sediment at the bottom of Lake Erie are taken up by zebra
mussels, and then the zebras are eaten by the round goby.
“And then, interestingly enough, round gobies are important prey for smallmouth bass that people
eat, and all of a sudden we have the opportunity for those PCBs that were stored in the sediments
to come up through the food chain and influence humans.”
So, Stein says, those contaminants that were trapped in the sediment now have a pathway up the
Gene Kim’s research is confirming the link between smallmouth bass and round gobies. He says
it’s clear round gobies like to eat zebra mussels. But it’s less clear whether bass prefer to eat gobies
over other prey fish. So, Kim devised a laboratory behavior study that let the smallmouth bass
choose between several types of prey, including gobies, emerald shiners, and crayfish.
“The interesting thing is that they actually target these emerald shiners more often than round
gobies, but emerald shiners have superior escape abilities.”
Round gobies, Kim says, just don’t swim away as fast – and so get eaten the most. He adds that
when compared with the stomach contents of Lake Erie bass, this laboratory result is borne out –
more gobies were consumed than any other prey.
Roy Stein says that this puts the system in a kind of double jeopardy.
“The combination of PCBs plus being a slow prey causes perhaps more PCBs to move up through
the food web than otherwise might be the case.”
PCBs have been linked to cancer and birth defects in humans – and they’re not the only
contaminants in the lake.
Other research indicates this new food chain might be helping other pollutants in the sediment find
their way to humans. For example, another Ohio State study finds methylmercury is also getting
into the food web through invasive species. Methylmercury in fish can cause neurological problems
for expectant mothers and other health problems.
Doug Haffner is the Canada Research Chair for Great Lakes Environmental Health and a professor
of Biological Sciences at the University of Windsor. He agrees a zebra mussel – round goby –
smallmouth bass food chain has created a route that exposes humans to harmful chemicals in lake
“For a chemical to be of concern to us, it has to be biologically available, it has to be able to enter a
human being or a fish or whatever it might be. Some chemicals may be out there but not available;
we can measure them, but they’re not really a risk to the ecosystem per se. But processes can
change, which make them available.”
Martin Berg is a professor of Aquatic Ecology at Loyola University Chicago. He says the non-
native species have had a similar impact on PCB transfer from Lake Michigan sediment.
“You can think of it almost like a conduit, like a pipe. Now we have a direct link, as you move up
the food web, to organisms that are going to be directly consumed by humans.”
And the problem spreads as the non-native species expand their range. Researcher Gene Kim says
that the implications are far-reaching.
“Not only are we just talking about a Great Lakes phenomenon – zebra mussels have already
escaped into the Mississippi drainage, and right now round gobies – we’re spending a lot of money
to prevent round gobies from entering that same drainage.”
Scientists’ concerns about toxins in the Lakes are not limited to how invasive species are changing
the food web. Researchers say that other changes caused by people can help harmful chemicals
trapped in sediments to return to the ecosystem. Ultimately, they say, each of these issues is part
of a much larger concern: the overall health of the environment.
For the Great Lakes Radio Consortium, I’m Carolyn Gramling.
A spiny fish that can hunt in the dark has invaded Lake Michigan. The foreign fish is known as the Eurasian ruffe. As the Great Lakes Radio Consortium’s Annie MacDowell reports, biologists fear the ruffe could harm the lake’s yellow perch population:
A spiny fish that can hunt in the dark has invaded Lake Michigan. The foreign fish is known as the Eurasian ruffe. And as the Great Lakes Radio Consortium’s Annie MacDowell reports, biologists fear the ruffe could harm the lake’s yellow perch population:
Experts say the ruffe is originally from the Black and Caspian seas, and it’s an
efficient little machine. It lays enormous numbers of eggs and has no predators because of its spiny skin. Gary Lamberti is a professor in the department of biological sciences at the University of Notre Dame.
He says the ruffe are depleting the yellow perch’s food supply.
“The Eurasian ruffe are specialists on that food, that is they eat that food all the
time. And those are the worms and aquatic insects that are found at the bottom of
the lake. That’s what ruffe eat and that’s also what perch eat at a certain stage of
their lives. But ruffe do it all the time and they do it better.”
Lamberti says the yellow perch’s population is already declining in the Great Lakes,
probably due to competition from many invasive species.
The ruffe could be another blow to the commercial fishing industry, as yellow perch
are widely harvested for food and are a favorite among sportsmen.
The Eurasian ruffe probably migrated from Lake Superior, where they were first
discovered in the 80’s.
For the Great Lakes Radio Consortium, I’m Annie MacDowell.
For many years, state and federal wildlife officials have considered the cougar extinct in the Great Lakes region. However, many people claim to have seen the large predatory cat long after it supposedly disappeared. Conservationists debate whether these sightings are real and if they are, they wonder whether the cougars are wild or merely escaped pets. Investigations are underway in many states, including Minnesota, Wisconsin and Pennsylvania, and in Canada. Now, a wildlife biologist in Michigan says he has proof that a breeding population of wild cougars is living in the Upper Peninsula. The Great Lakes Radio Consortium’s Gretchen Millich reports:
In many ways, the double-crested cormorant is a wildlife success story. The
birds were almost wiped out by pesticide exposure in the 1960’s. But in
recent years, they’ve returned in large numbers to prime fishing areas in
the Great Lakes and elsewhere. In fact, they’re so good at catching fish,
commercial fishermen have been affected. In the first of a two part series,
the Great Lakes Radio Consortium’s Karen Kelly found that the biologists who
protect these birds are also looking for ways to get rid of them:
It’s nothing new to get predators to get rid of pests. The colorfuland cute ladybug, for example, loves to devour aphids, mites andmealybugs and is used by many people instead of pesticides. But workingwith these flying predators presents some problems. Now, one researchermay have a solution. The Great Lakes Radio Consortium’s Wendy Nelsonreports: