Tag: prey

Ten Threats: The Beloved Invader

  • Because alewives are the main source of food for some sport fish, some people forget that they're an invasive species. (Photo courtesy of NOAA Fishery Service)

As we look at the “Ten Threats to the Great Lakes,” we’re spending some time examining the effects of the alien invasive species that have changed the Lakes. One of the first invasive species to arrive in the Great Lakes was the alewife; it’s native to the Atlantic Ocean. It has become the most beloved of all the invasives. That’s because it’s food for the most popular sport fish in the Great Lakes. But in the beginning, the sport fish was introduced to get rid of the alewives. Peter Payette reports:

Transcript

Today we’re continuing our series on Ten Threats to the Great Lakes. The Great Lakes Radio Consortium’s Lester Graham is our series guide:


As we look at the “Ten Threats to the Great Lakes,” we’re spending some time examining the effects of the alien invasive species that have changed the Lakes. One of the first invasive species to arrive in the Great Lakes was the alewife; it’s native to the Atlantic Ocean. It has become the most beloved of all the invasives. That’s because it’s food for the most popular sport fish in the Great Lakes. But in the beginning, the sport fish was introduced to get rid of the alewives. Peter Payette reports:


When autumn arrives in Northern Michigan, salmon fishermen line the rivers. The fish, native to the Pacific Ocean, swim upstream to spawn and then die. That’s why Tim Gloshen says they’re not interested in his bait.


“But if you irritate ’em enough and keep putting it in front of them, they’ll snap at it sometimes and you got to be ready when they hit it and set your hook.”


Anglers caught eight million pounds of salmon in Lake Michigan last year. Most of the fish are caught out in the lake.


“I got buddies that are catching couple hundred a year out there. They’re out there twice a week at least, all summer long, you know.”


Tim and his buddies and everyone else who fishes for salmon in the Great Lakes are at the top of the food chain. The money they spend on food, lodging, tackle, and boats figures heavily into decisions about how to manage the Lakes.


But it wasn’t always so.


Pacific salmon were stocked here about forty years ago to control the invading alewives. The native lake trout had just about been wiped out by overfishing and the sea lamprey. With no big predators left, the alewife population exploded.


At one point, it was estimated that for every ten pounds of fish in Lake Michigan, eight were alewives. Occasional die-offs would cause large numbers of alewives to wash up on beaches all over the Great Lakes. Historian Michael Chiarappa says all this was happening as America was feeling the urge to get back in touch with nature.


“And that’s when you get this rise in greater interest in sport fishing, recreational fishing, hunting. Teddy Roosevelt sort of epitomized the spirit of the strenuous life; get back out there and engage nature. It’s good for the soul, it’s good for the body, it’s good for the mind.”


So the salmon was brought in to control the alewife population and transform the Great Lakes into a sport fishing paradise. And it worked. But alewives remained the best food source for the ravenous salmon.


So now a healthy alewife population is seen as a good thing by the states that benefit economically from the recreational fishing. Mark Holey, with the U.S. Fish and Wildlife Service says this has caused people to forget alewives are an invasive species.


“If alewives were knocking on the door today, there may be a much different discussion about it. It may be more like the Asian carp.”


How the alewife would compare to Asian carp is unknown, because the Asian carp has been found in the Mississippi River, but not yet in the Great Lakes. What is known is that when alewives are abundant, native fish don’t do well. For example, Holey says biologists used to think PCBs caused many young lake trout to die. Now they know early mortality is mostly due to thiamin deficiency.
Thiamine is a vitamin lacking in lake trout that eat too many alewives.


“From the studies that we’ve been involved with, anywhere, right now, anywhere between thirty to fifty percent of the females that we take eggs from show some… their eggs show some signs of thiamine deficiency. Which means survival of those eggs are impaired.”


In some cases, none of the eggs will survive. So a worse case estimate would be half of the wild lake trout in the Great Lakes can’t reproduce because of alewives. This is why advocates for native fish species have been happy to see the alewife populations decline in recent years. They almost disappeared from Lake Huron.


Mark Ebener is a fisheries biologist for the Chippewa Ottawa Resource Authority. He says the government agencies that stock salmon and lake trout should stock more than ever to keep pressure on the alewife. Ebener thinks with alewife numbers down, there’s an opportunity to reestablish the native herring as the main prey fish in the Lakes, especially in Lake Huron.


“Saginaw Bay used to have a huge population of lake herring that’s essentially gone. They used to have a tremendous commercial fishery for it, and people used to come from miles around to buy herring there, and everybody in the lower end of the state used to have herring come fall and the springtime when the fishers were fishing, but they’re gone.”


This opportunity to bring herring back might not last much longer. The warm weather this past summer will probably help alewives rebound next year.


For the GLRC, I’m Peter Payette.

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Owls Crossing Border Into U.S. For Food

  • Owls have been migrating from Canada to the U.S. in search of easy prey. (Photo by Florian Engels)

Owls have been moving from their native habitat in Canada into the United States. Researchers say the number of owls making the trip is unprecedented. The Great Lakes Radio Consortium’s Christina Shockley
reports:

Transcript

Candian owls have been moving from their native habitat into the United States, including MN, WI, MI, and IA. Researchers say the number of owls making the trip is unprecedented. The Great Lakes Radio Consortium’s Christina Shockley reports:


The Great Gray Boreal , northern hawk, and snow owls live in
the upper reaches of Canada. But hundreds of owls have been flying into the U.S. in search of food. The small mammals they prey on in their native range, like mice, voles, and lemmings, are in the midst of a population crash. Susan Foote-Martin is with the Wisconsin Department of Natural Resources. She says it’s common for small-mammal populations to rise and fall. So, even though the owls expend a lot of energy to get here, their stay is temporary.


“They’ll definitely move back. They’re only down here because the population of the animals they eat are down. But there’s also another consideration, and that’s deep snow cover in the areas where they normally live.”


Foote-Martin says the owls have a hard time catching their prey because they burrow deep into the snow. She says if the owls continue to fly into the U.S. over several years, it could signal a problem in their native habitats.


For the Great Lakes Radio Consortium, I’m Christina Shockley.

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States Ready for Wolf Delisting?

  • Once hunted nearly to extinction, the gray wolf has recently rebounded under the protection of the Endangered Species Act. Now, the U.S. Fish and Wildlife Service is proposing to take the wolf off of the Endangered Species List and hand wolf management back to the states. (Photo by Katherine Glover)

The U.S. Fish and Wildlife Service wants to remove the eastern population of the gray wolf from the Endangered Species List and turn over wolf management to state control. But not everyone thinks the states are up for it. The Great Lakes Radio Consortium’s Katherine Glover has the story:

Transcript

The U.S. Fish and Wildlife Service wants to remove the eastern population
of the gray wolf from the Endangered Species List and turn over wolf management
to state control. But not everyone thinks the states are up for it. The Great Lakes Radio
Consortium’s Katherine Glover has the story:


(sound of wolves howling)


The image of the wolf has always had a powerful effect on people. Wolves seem dangerous,
mysterious, romantic. They are a symbol of the untamed wilderness. Before Europeans came
to America, wolves roamed freely on every part of the continent. In 1630, the colony of
Massachussetts Bay started paying bounties to settlers for killing wolves. Over the next
300 years, wolf killing spread across the country, until all that was left was a few small
pockets of surviving wolf packs.


When the Endangered Species Act passed in 1973, the only wolves left to protect in the
Midwest were in Northern Minnesota. By some estimates, there were as few as 350 of them.


Today, Minnesota has a healthy wolf population of around 2400 animals, and smaller populations
are growing in Wisconsin and Michigan. Becaue of this success, the U.S. Fish and Wildlife Service
has proposed removing the animals from the Endangered Species List. This would mean wolves would
no longer be federally protected – it would be up to the states.


(sound of gate opening)


Peggy Callagan works with captive wolves at the Wildlife Science Center in Minnesota. She’s the
Center’s co-founder and executive director. She and her staff research ways to minimize
conflicts between wolves and people. Callahan is looking forward to seeing the wolf taken off
the Endangered Species List.


“It’s a good thing for the Endangered Species Act, to take a wolf off or an eagle off or a
peregrine off when it has recovered. The act was not established to provide a permanent
hiding place. It was established to protect a species until such time that they could be
managed in a different way.”


Wisconsin and Michigan have wolves because young born in Minnesota have migrated east to start
their own packs. Callahan says how Minnesota manages its wolves will affect wolf numbers in the
Midwest. And she isn’t crazy about Minnesota’s current wolf management plan, which has different
rules for different parts of the state.


“Now, there’s a boundary; there’s a boundary called a wolf zone, and there’s a boundary that’s
called the ag zone. And nobody likes it. We went backward.”


In Northeastern Minnesota, where the majority of wolves are, landowners can only kill wolves
if they can demonstrate an immediate threat to pets or livestock. In the rest of the state, where
there is more agriculture and more people, the rules are more lenient. On their own property,
landowners can kill any wolf they feel is a danger, without having to prove anything to the state.


The Sierra Club is opposed to taking the wolf off the Endangered Species list, largely because
of Minnesota’s management plan. Ginny Yinling is the chair of the Wolf Task Force of the Sierra
Club in Minnesota.


“They’ve pretty much given carte blanche to landowners, or their agents, to kill wolves
pretty much at any time in the southern and western two thirds of the state; they don’t even
have to have an excuse, if a wolf’s on their property they can kill it. Instead of this being
what should have been a victory in terms of wolf recovery and the success of the Endangered
Species Act, instead we’re afraid it’s going to turn into something of a disaster.”


Yinling is also concerned with the protection of wolf habitat, such as den sites, rendezvous
sites, and migration corridors.


“The current management plan protects none of those areas; it leaves it entirely up to the
discretion of the land managers.”


But wildlife managers say these are not critical for a large wolf population
like Minnesota’s. Mike DonCarlos is the wildlife program manager for the Minnesota
Department of Natural Resources.


“As you look at the range of species that are threatened by habitat change, ironically the wolf
in Minnesota is not one of them. As long as there’s a prey base that continues, wolves should
do just fine. The key is mortality rates and availability of food.”


In Wisconsin and Michigan, where there are fewer wolves, state laws will continue to protect
wolf habitat. Peggy Callahan says she has faith that the wolves will be fine, even if the
Minnesota state plan is not perfect. But at the Sierra Club, Ginny Yinling says they have
plans to challenge wolf delisting in court.


For the Great Lakes Radio Consortium, I’m Katherine Glover.

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Anglers Competing With Cormorants

  • The cormorant population is booming in the region, and some anglers say they're competing too hard with the birds for fish. (Photo courtesy of Steve Mortensen, Leech Lake Band of Ojibwe)

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:

Transcript

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:


(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
last year.


“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
different way.


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
away.


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
long-term.”


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
isn’t it?”


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
populations.


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.

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Bugs Released to Munch on Invasive Plant

  • Purple loosestrife's looks are deceiving. It's a beautiful plant, but researchers say it has caused enormous damage in many parts of the country. An imported beetle has now shown significant signs of controlling the plant.

Purple loosestrife is a beautiful plant. It’s tall… and each cone-shaped stem produces hundreds of flowers. When the plants bloom in mid-summer they can create a sea of purple in wetlands throughout the region, but the ability of the plant to spread and reproduce in great numbers is what concerns scientists and land managers. Over the years they have been working to control it. The Great Lakes Radio Consortium’s Mark Brush says one way they’re trying to control it is by releasing a bug to eat the plant:

Transcript

Purple Loosestrife is a beautiful plant. It’s tall… and each cone-shaped
stem produces hundreds of flowers. When the plants bloom
in mid-summer they can create a sea of purple in wetlands
throughout the region… but the ability of the plant to spread and
reproduce in great numbers is what concerns scientists and land
managers. Over the years, they have been working to control it.
The Great Lakes Radio Consortium’s Mark Brush says one way
they’re trying to control it is by releasing a bug to eat the plant:


Roger Sutherland has lived next to this wetland for more than 35
years.

He helped build a boardwalk over the soggy marsh so that he can
get a close-up view of some of his favorite plants:


“You see that plant with the big green flower? Yep. That… and
there’s more along here… that’s a pitcher plant. These are insect
eating plants and there’s another one called sundew here… here’s
some right in here…”

(sound under)


But like many wetlands throughout the country, this wetland has
been invaded by a plant originally found in Europe and Asia.


Purple Loosestrife was introduced as an ornamental plant.
It was a
beautiful addition to gardens, but once it took
hold in the environment,
it out-competed native plants.

Frogs, birds, and insects have relied on these native plants for
thousands of years. Purple Loosestrife is crowding out their habitat.


“We’re going to get a lot more shade with this loosestrife.. and so
these plants that are on these hummocks here…
these little insect
eating plants and so on… just can’t tolerate that shade, so we’ll
probably lose ’em unless I can keep it open here… and I am trying
to keep some of it open.”


The plant spreads quickly… that’s because one plant can produce
more than two million seeds that spread with the wind, like dust.

So when it moves into an area, it often takes over creating a thicket
of purple with a dense root system.

Land managers have seen populations of ducks, and turtles
disappear when loosestrife takes over…

And research has shown that the plant can reduce some frog and
salamander populations by as much as half.


So land managers wondered what to do to stop the spread of this
weed.

They initially tried to control the plant by digging it up… or by
applying herbicide to each plant.

Trying to kill the plants one by one is hard work… especially
considering how abundant purple loosestrife is.

But researchers have hope because of a bug.


(Sound of volunteers planting loosestrife)

Volunteers have gathered here in Ann Arbor, Michigan to plant
purple loosestrife.

They’re putting dormant loosestrife roots into potting containers and
adding fertilizer.


(more sound)


When the plants leaf out they’ll be covered with a fine mesh net and
become home to a leaf-eating beetle known as galerucella.

And galerucella loves to munch on purple loosestrife.

The volunteers are creating a nursery to raise more beetles.

Once they’ve got a bunch of beetles growing on the plant… they’ll
take it to a nearby wetland… and the bugs will be released into the
wild…


(sound up)


Linda Coughenour is a member of the Audubon Society.

Her group is working with state and local agencies to raise and
release these beetles.

She says tackling purple loosestrife invasions is a big task – and
governments need help from volunteers to deal with the problem:


“This is a serious problem throughout the entire Great Lakes
wetlands… it has migrated from the East Coast to the Midwest…
so, uh.. the problem’s just too big – so they thought up doing this
volunteer project and they’ve enlisted people all over the state… and
we’re just one of those.”


Volunteers have have been releasing their beetles into this wetland
for few years now and they’re beginning to see progress:


“It’s going really well… for a while we got off to a slow start, but for two
years now we’ve found evidence that the beetles are reproducing on their
own. We see little egg masses, we see larva that are starting to eat
the plants, we see adult beetles on the plants that have wintered
over. And that’s the thing, to get them to do it on their own.”


But releasing a foreign species into the wild is always a concern.

There are a number of examples of bugs released into the wild to
eliminate a pest, but ended up causing a problem themselves.

But before importing a bug that will prey on plants – the federal
government requires testing to make sure it won’t eat other plants.


The tests have been done.


And researchers feel that this is an extremely finicky bug…


Berndt Blossey is a specialist on invasive plants and ways to control
them.

He says the beetles were tested on native plants before they were
allowed to import the bugs:


“And it was shown there that they will not be able to feed and
develop on the plants. They will occasionally nibble on them, but
they will not be able to develop on them and they usually move off
after they have taken a bite, and they move off to other plants.”


The leaf beetle is not the only bug researchers are importing.

They’re also importing two other beetles known as “weevils.”

One that feeds on loosestrife flowers, and one that feeds on its root
system.

Blossey says more than one bug is needed to keep the plant from
growing back:


“Loosestrife will rebound from resources in the root stock. If you
have the root feeder in the system as well, these fluctuations will be
dampened, so loosestrife will not be allowed to comeback to higher
levels.”


(sound of wetland up)


People who admire the diversity of plants and animals in wetlands
like the idea of keeping purple loosestrife in check.


Roger Sutherland welcomes the bugs.

He believes they’ll help him keep this wetland open for the plants,
birds, and insects he’s come to know over the years:


“We know that the purple loosestrife will probably always be here.
But if we can bring it down to a manageable level, where you’re going
to have a pocket here and a pocket there… and you can kind of
maintain the integrity of this wetland system… then you can’t ask for
anything more than that.”


And researchers say that’s the goal.

To help these wetlands reach a balance… so that plants and animals
that have evolved to rely on these wetlands for thousands of years…
can continue to do so.

For the Great Lakes Radio Consortium, I’m Mark Brush.

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Threat Increasing From Invasive Fish

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:

Transcript

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.

Whoopers Go It Alone on Spring Flight

A high-profile flock of whooping cranes may be winging its way back through the Midwest in the next few days or weeks. The Great Lakes Radio Consortium’s Chuck Quirmbach reports:

To find out more about the migrating cranes you can go to: www.bringbackthecranes.org and www.operationmigration.org.

Transcript

A high-profile flock of whooping cranes may be winging its way back through the Midwest in the next few days or weeks. The Great Lakes Radio Consortium’s Chuck Quirmbach reports:

The cranes would be the first migrating flock of whoopers in the eastern U.S. The birds have left their winter home in Florida, and wildlife biologists hope the cranes are on their way to a summer nesting site in Wisconsin. The whoopers are flying on their own this spring, after having followed ultra light aircraft on their southerly migration last fall. U.S. Fish and Wildlife Service spokesperson Charles Underwood says one of the biggest dangers on the northbound journey is from predators.

“Both bobcats and coyotes and as they get further north the possibility of wolves taking one of the birds is always of concern to us.”

Underwood is also urging people not to get to try to get too close to the whooping cranes. He says wildlife officials are trying to keep the huge birds as wild as possible. Two web sites will track the cranes’ progress.

For the Great Lakes Radio Consortium, this is Chuck Quirmbach reporting.

Wolf Killed by Government Order

A timber wolf has been shot by a federal officer in Wisconsin. For the
past twenty-five years the wolf has been listed on the federal
endangered species list. But now the wolf’s status is being changed from
endangered to threatened making it easier to use lethal force on problem
wolves. The Great Lakes Radio Consortium’s Nick Van Der Puy has more: