Tag: invaders

Lake Huron’s Invasive Species

  • Filmmaker John Schmit says he wanted to make this film to show how even the smallest invader could mess up the delicate balance of life in the lake. (Photo courtesy of the NOAA GLERL)

You might call Lake Huron the forgotten Great Lake. There are no major cities on its shores. It doesn’t get the media attention the other four Great Lakes do. But its problems are just as bad or worse. Rebecca Williams reports a new documentary tells the story of Lake Huron’s struggle with dozens of alien invaders… and the biologists and fishermen who are trying to reclaim their lake:

Transcript

You might call Lake Huron the forgotten Great Lake. There are no major cities on its shores. It doesn’t get the media attention the other four Great Lakes do. But its problems are just as bad or worse. Rebecca Williams reports a new documentary tells the story of Lake Huron’s struggle with dozens of alien invaders… and the biologists and fishermen who are trying to reclaim their lake:

The documentary Lake Invaders is a cautionary tale about opening the door to strangers. It tells how Lake Huron was opened up to alien invasive species. The film paints fish biologists as the heroes rushing in.

“Seems like it always has to wait until it’s at a disaster level before you know, we can start fixing it… we’re constantly putting out these biological fires, running from fire to fire, to try to keep them under control. We have to find another way to approach this.”

More than 180 non-native species have gotten into the Lakes… and some of them have turned everything upside down. Long, slithering, blood-sucking parasites called sea lamprey were the first to get in. They slipped through a canal that connects the Atlantic Ocean and the Great Lakes. Lamprey killed off most of the big predator fish in the Lakes.

Then… came the alewife. Since the lamprey had taken out the top predators… there was nothing to eat the invading alewives. In the film… biologist Jeff Schaeffer explains how the small fish took over the lakes.

“At that time over 90% of the fish biomass of Lake Michigan and Lake Huron was probably dominated by the exotic alewife. One of my colleagues refers to the Great Lakes at that time as alewife soup.”

Suddenly… there was a major stinking mess. Each spring, hundreds of millions of dead alewives washed up on shore and rotted. Not the best thing for tourism.

Filmmaker John Schmit says he was surprised to learn what happened to the lakes next.

“The funny thing about the Great Lakes is there’s Pacific salmon in them.”

Schmit says biologists brought in millions of salmon from the Northwest to control the alewives. The crazy thing is… it worked. In the film we see how a 4 billion dollar sport fishing industry was born. And the native fish of Lake Huron were pretty much forgotten about.

The salmon fishery boomed for decades. Until the alewives crashed in 2003.

Fisher Doug Niergarth says then… the salmon started starving.

“Two years ago we saw some monster salmon heads that were sitting on little dwarfed bodies. And it was the ugliest thing and rather nasty. Just skinny and withered away. It was the nastiest thing you ever done seen.”

The fishing industry started slipping away. Marinas just scraped by. Tackle shops and motels closed. People finally realized there was something wrong with the lakes.

John Schmit says he wanted to make this film to show how even the smallest invader could mess up everything… both the delicate balance of life in the lake and the people who fish it and depend on money from tourism.

“Lake Huron has been the most impacted by the newest invaders. My personal concern, my investment in the Great Lakes and making this documentary is for people to be aware of the kind of damage invasive species can do to these huge lake systems.”

He says his film Lake Invaders is an example of what invasive creatures can do… not just to Lake Huron… but any ecosystem.

For The Environment Report, I’m Rebecca Williams.

Related Links

Tiny Pest Threatens the Las Vegas Lights

  • Hoover Dam's backside stretches more than 700 feet from top to bottom, but the dam's seeing trouble from the tiny aquatic zebra mussel. (Photo by Shawn Allee)

Hoover Dam generates some of the power that lights Las Vegas all night long. But there’s something
that’s making that job a bit more difficult. Shawn Allee found out, it’s a tiny aquatic pest:

Transcript

Hoover Dam generates some of the power that lights Las Vegas all night long. But there’s something
that’s making that job a bit more difficult. Shawn Allee found out, it’s a tiny aquatic pest:

The usual tour of Hoover Dam starts at the visitor’s center – way at the top.

Robert Walsh works with the federal agency that runs Hoover.

He says, go ahead – look over the edge.

Allee: “OK. That’s creepy. Seriously, that’s creepy.”

Walsh: “It’s spooky. Are you afraid of heights?”

Allee: “No, they don’t bother me at all.”

The dam stretches down 700 feet, and it holds an enormous reservoir – Lake Mead.

This tour is awesome, but Walsh says there’s another tour, too.

It’s, um, NOT so awesome.

It’s all about the trouble the tiny quagga mussel is causing Hoover and other nearby dams.

To get that tour, Walsh takes me to Leonard Willet.

Allee: “Where are we right now?”

Willet: “It’s kind of a work station where all the quagga mussel control activities take place
for Hoover Dam.”

Allee: “It’s quagga mussel central for this area?”

Willet: “Exactly.”

Willet first heard quagga mussels were growing in the nearby Lake Mead reservoir in 2007.

He called an expert for advice.

“First thing out of her mouth was, ‘I’m sorry to hear that.’ I knew it was a lot more serious.
And I asked her what we’re in for.”

Willet learned quickly enough – quagga mussels attach to nearly anything underwater.

He shows me a sandal that was in water – and is smothered in them.

They’re like clams the size of your pinky fingernail.

“We went from zero to THAT in seven months.”

And that’s the problem.

Hoover Dam uses water from Lake Mead to spin generators.

The water moves around in pipes – and quagga mussels can attach to them – just like on that sandal.

Allee: “What does that mean in a real practical sense?”

Willet: “Our intake towers would close off. Once you start closing off, you can’t spin the
generators. That’s just kind of the big view of it.”

Zero power generation.

That’s the worst-case scenario. It hasn’t happened – but it’s a fight to prevent it.

“Now, we’re going to go down to the third floor, which is the generator floor.”

The generators are inside broad metal cylinders.

Big water pipes turn the generators. Smaller ones cool them off.

“Well, we circulate cold water from those pipes. If those start to plug up with mussels, then
you can’t keep a generator cool, if those … it shuts down due to overheating.”

Right now, it takes a lot of scraping to keep everything clear.

All this effort’s adding up – Willet says he’ll spend 2 million dollars soon on new equipment.

Even with that, Willet is still a bit jittery about some pipes outside, at the very bottom of the dam.

“The one that’s probably the scariest of all is, we have a fireline that runs around here.
Mussels love it. Then, your firelines, when they’re needed, are plugged with mussels. So
that’s another area you have to really be careful of, safety-wise.”

This didn’t have to happen.

Quagga mussels invaded eastern rivers and the Great Lakes first.

Experts figure the mussels hitched a ride West on someone’s fishing boat.

Apparently – someone didn’t clean their boat properly – and mussels dropped into Lake Mead.

Allee: “When they built this amazing structure during the Depression, do you think they had
any idea that something like this could ever happen?”

Willet: “I think there was a lot of disagreement among professionals that a little mussel the
size of your finger nail could impact a large hydro facility, but we’re quickly learning a bunch
of them can impact water and power delivery.”

Willet says if boaters aren’t careful – they’ll spread quagga mussels to the Pacific Northwest, where
there’re lots of dams and hydro power plants.

After all, if it can happen at mighty Hoover Dam – it could happen anywhere.

For The Environment Report, I’m Shawn Allee.

Related Links

States Pass Feds on Invasives Law

  • Federal restrictions have not stopped importation of invasive species. Now some states are passing laws that will stop some ocean-going ships from docking in their ports. (Photo by Lester Graham)

US ports receive more than imported cargo.
They often receive fish and other aquatic organisms
from foreign ports. They stow away in the ballast
water of cargo ships. Once in US waters, some of
the foreign species become invaders, damaging the
ecosystem. The federal government has done little
to stop these invasive species. Rick Pluta reports now some states have decided to take
things into their own hands:

Transcript

US ports receive more than imported cargo.
They often receive fish and other aquatic organisms
from foreign ports. They stow away in the ballast
water of cargo ships. Once in US waters, some of
the foreign species become invaders, damaging the
ecosystem. The federal government has done little
to stop these invasive species. Rick Pluta reports now some states have decided to take
things into their own hands:


The damage caused by invasive species carried to the US in
ballast water is not only harmful to the environment, but it
hurts the economy. The federal regulations have not stopped the
problem. So, states such as California and Michigan have passed
laws that require foreign ships to treat ballast water like
pollution. They have to clean it up before they can discharge it
into a port. The problem is, almost no ships have a way to treat
the ballast.


In Michigan, the Great Lakes shipping industry is trying to delay
the new Michigan rules. Shipping companies, port owners, and
dock workers say Michigan’s new rules are jeopardizing jobs
without actually stopping the introduction of new species into
the Great Lakes.


The damage caused by invasive species carried to the US in
ballast water is not only harmful to the environment, but it
hurts the economy. The federal regulations have not stopped the
problem. So, states such as California and Michigan have passed
laws that require foreign ships to treat ballast water like
pollution. They have to clean it up before they can discharge it
into a port. The problem is, almost no ships have a way to treat
the ballast.


In Michigan, the Great Lakes shipping industry is trying to delay
the new Michigan rules. Shipping companies, port owners, and
dock workers say Michigan’s new rules are jeopardizing jobs
without actually stopping the introduction of new species into
the Great Lakes.


People in the shipping business say the problem is Michigan is
the only state in the Great Lakes region that is requiring ocean-
going freighters to install expensive technology as a condition
of using one of its ports.


John Jamian is the president of the Seaway Great Lakes Trade
Association. He says requiring ocean-going freighters to install
expensive technology before they can dock in Michigan ports won’t
solve the problem. The ships will just go to other Great Lakes
ports.


If a ship goes to Windsor or Toledo that doesn’t have these rules
and regulations, they will discharge their cargo. If there were
any critters on those ships they could still swim or crawl into
Michigan waters, so you still haven’t solved anything.


Jamian represents the owners of ships that travel from the
Atlantic Ocean to the Great Lakes via the Saint Lawrence Seaway.
He says ship owners will very likely avoid Michigan ports, and
choose to unload at ports in other states and Canada:


“The fact of the matter is that they’re not going to put an
expensive piece of equipment just because Michigan calls for it
on their ship when in fact it may not be acceptable anywhere else
in the world and it might just be easier to take that cargo
across the river and unload it where they don’t have these
regulations.”


And for Michigan ports that are near other competing ports,
that’s a concern. Patrick Sutka is the treasurer for Nicholson
Terminal and Dock Company at the Port of Detroit:


“We fear these ships may be going to other ports, such as Windsor
right across the waterway, or other competitors of ours such as
Toledo or Cleveland.”


At the height of the shipping season, there might be three
freighters at a time moored to the docks, offloading steel and
other cargo. A hundred trucks a day will move in and out of the
docking area to get those commodities to factories.


On the dock right now are dozens of stacks of 20-ton slabs of
steel from France and Russia. That Russian steel was most likely
shipped from a port in the Caspian Sea or the Black Sea. The
freighters take on ballast water from those seas for the voyage
to the Great Lakes. That ballast water helps keep the ships low
and steady in the water.


The ships are required to exchange the water in deep ocean mid-
journey. The salt water is supposed to kill the fresh water
organisms. But, some organisms can survive the trip. That’s how
zebra mussels, quagga mussels and the round goby fish made their
way from the Balkans to the Great Lakes.


Those invasive species and others combine to cost the economy an
estimated 5 billion dollars a year. For example, zebra
mussels cost taxpayers and utility customers. It shows up in
your power bill because the utilities have to pay divers to
scrape the crustaceans off pipes carrying cooling water to power
plants.


Shipping companies, port owners, and dock workers’ unions are all
pressuring Michigan to hold off on enforcing its new law. What
they’d really like is for the federal government to step in,
negotiate with Canada, and create a regional set of rules for
combating aquatic invaders:


“…But the federal government has not had the guts or the
gumption to step up to the plate and get this done.”


Patti Birkholz chairs the Michigan Senate Environmental Affairs
Committee. She sponsored the law:


“So we’re going to do it on a state-by-state basis. Our eco-
system within the Great Lakes is what many scientists have termed
‘on the tipping point.’ We cannot deal with any more invasive
species in this system, and we know the majority of the invasive
species come through the ocean-going vessels. They know they’re
the cause. We know they’re the cause. We’ve got to deal with this
situation.”


Michigan’s new law is as much a political statement as anything
else and other states are starting to follow Michigan’s lead.
Birkholz says Wisconsin and New York could pass ballast standards
this year.


In the mean time, Michigan environmental officials say they
intend to enforce the state’s requirements when the Great Lakes
shipping season resumes in the spring. But, so far, no ocean
freighters have applied for a permit to dock at a Michigan Port.


For the Environment Report, this is Rick Pluta.

Related Links

Combating Inland Invasives

  • Eurasian Watermilfoil is one of the non-native species that has invaded inland lakes. (Photo courtesy of National Park Service)

Invasive plants, fish and other creatures are threatening many inland lakes. Environmentalists and property owners are trying to stop the spread…before the invaders dramatically alter the smaller bodies of water. The Great Lakes Radio Consortium’s Ann-Elise Henzl reports:

Transcript

Invasive plants, fish and other creatures are threatening many inland
lakes. Evironmentalists and property owners are trying to stop the
spread…before the invaders dramatically alter the smaller bodies of
water. The Great Lakes Radio Consortium’s Ann-Elise Henzl reports:


It’s strange to think that plants and animals from Europe, Asia and Africa
are living in small lakes in the Midwest. Boaters have taken invaders
there…after picking them up in the Great Lakes.


The big lakes are home to more than 160 aquatic invasive species,
including Eurasian Watermilfoil. The stringy plant grows in thick
clusters that get up to 12 feet tall.


“I have seen lakes where if you fell out of the boat in these massive
weeds and you weren’t wearing a life jacket, I don’t care how good a
swimmer you are, you would sink. You can not struggle your way
through these thick entanglements of weeds.”


Ted Ritter leads an effort to reduce aquatic invasive species…in
Wisconsin’s Vilas County.


(Sound of pontoon motor)


On one afternoon he takes his pontoon boat on a lake that had an
infestation of Eurasian Watermilfoil.


“It is a very aggressive plant and it has no natural predators to control its
growth, it grows up to two inches a day.”


When Eurasian Watermilfoil finds conditions it likes, it takes over
quickly. A piece as small as two inches can break off, and float away to
create a new plant.


Eurasian Watermilfoil is widespread in northern Michigan… northern
Wisconsin and other places. It’s one of dozens of aquatic invasive
species on the move in the region.


One of the worst invaders is zebra mussels. They can ravage a lake’s
ecosystem.


(Sound of motor boat)


So far, they’ve made it to just one lake in northern Wisconsin. Mike
Preul with the Lake Superior Chippewa scuba dives there, to count the
mussels. Three years ago, he found 7 adults per square meter. This year,
he counted more than 14-hundred:


“They’re still increasing. What they’ve seen in other systems is that just
like with any other exotic species they’ll come in, the population will
explode, they’ll kind of eat themselves out of house and home, and then
they’ll come down to a level and reach a steady state.”


No method has been discovered to get rid of zebra mussels, but there are
ways to control some invaders.


Herbicides can be used to kill Eurasian Watermilfoil, and some property
owners chip in to buy aquatic insects to kill the plants.


Les Schramm did that on his local lake:


“As the larvae hatches it burrows into the stem of the Eurasian
Watermilfoil and sort of eats out the center vascular part, and it falls over
and dies.”


People fighting aquatic invasive species say it’s like fighting weeds in a
garden — the work never stops and it can be expensive.


Ted Ritter of Vilas County says it costs thousands of dollars to treat a
lake once. So, often people do nothing.


Ritter says that can hurt the environment. He says it can also threaten the
economy, in areas like northern Wisconsin that rely on tourism.


Ritter says the invaders can reduce the appeal of a lake. He mentions a
plant called “curly leaf pondweed.” When it dies in the middle of
summer, it creates algae blooms that look like slimy green pillows:


“When people arrive at resorts and they look out and they see that very
unappealing lake they say ‘I’m not staying here,’ and they go somewhere
else. When realtors bring prospective buyers out to look at a property,
people get out of their car and they go right to the lake and they say ‘oh
my, I’m not even interested in looking at the house. This lake is
horrible.'”


Because it’s so difficult to control invasive species, Ritter and others
fighting the invaders focus on prevention.


Local volunteers and workers from the Wisconsin Department of Natural
Resources spend hours at boat landings. They urge people to clean their
boats, trailers, and fishing gear thoroughly when going from lake to lake,
that can keep unwanted plants and creatures from traveling along.


For the GLRC, I’m Ann-Elise Henzl.

Related Links

Ten Threats: Break in the Food Chain?

  • Diporeia are disappearing from Lakes Michigan, Huron, Erie, and Ontario. The actual size of a diporeia is ½ an inch. (Courtesy of the EPA)

Some of the life in the Great Lakes has been hit hard by industry and trade. Pollution and
invasive species have hurt some of the native plants and animals important to the food
chain. While popular game fish might be the first to come to mind, it’s a little organism
at the bottom of the food chain that has biologists and fishing experts most concerned.
The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

In a survey, experts said one of the Ten Threats to the Great Lakes is a disappearing
species. Some native fish populations and organisms are declining. Our guide through
the Ten Threats series is Lester Graham.


Some of the life in the Great Lakes has been hit hard by industry and trade. Pollution and
invasive species have hurt some of the native plants and animals important to the food
chain. While popular game fish might be the first to come to mind, it’s a little organism
at the bottom of the food chain that has biologists and fishing experts most concerned.
The Great Lakes Radio Consortium’s Lester Graham reports:


(Sound of swinging doors)


Jack Donlan is taking me behind the fish counter at Donlan’s Fish House. In the
backroom he’s scaling and filleting some whitefish.


“Of the fishes caught in the Great Lakes, whitefish is one of the big volume fishes. Lake
perch, walleye bring more money per pound, but I would think from a tonnage-wise,
whitefish, it’s an extremely popular fish.”


This is a popular place to get Great Lakes fish, but Donlan’s suppliers, the commercial
fishers, are worried about the catch. At some places in the Great Lakes whitefish aren’t
doing too well.


(Sound of Lake Guardian motors)


Tom Nalepa is trying to figure out why whitefish are struggling. He’s onboard the U.S.
Environmental Protection Agency research ship, the Lake Guardian. Nalepa is a
biologist with the National Oceanic and Atmospheric Administration’s Great Lakes
Environmental Research Lab. He’s been studying Lakes Michigan and Huron, and on
this day he’s getting ready to study the bottom of Lake Erie.


He’s not studying whitefish. He’s actually looking for a tiny shrimp-like crustacean, only an
eighth to a quarter inch long, called diporeia. Eighty-percent of the whitefish diet is
made up of diporeia.


“And what we’re seeing is a dramatic drop in populations, and not only drops, but there are
large areas now in all the lakes, except Lake Superior, that no longer have diporeia. This
is real concern because diporeia is a very important fish food.”


Researchers used to find eight to 10-thousand diporeia or more in a square meter of sediment just
a few years ago. Now, there are only a dozen or so, or none at all. Diporeia is one of the
mainstays of the bottom of the food chain, and Nalepa says whitefish aren’t the only ones
that eat the tiny critters in the sediment at the bottom of the lakes.


“Just about every type of species found in the Great Lakes will feed on diporeia at some
stage in its life-cycle. Diporeia is high in calories and has a high-energy content. It’s a
very good food, nutritious food source for fish.”


Without it, fish are not getting enough to eat. Marc Gaden is with the Great Lakes
Fishery Commission. He says when diporeia disappears, commercial fishers can’t help
but notice.


“Right now we’re seeing skinnier whitefish. Whitefish that are somewhat emaciated in
some areas because they just don’t have as much of these low-end of the food web organisms
to eat, and we think it’s related to an invasive species that came in.”


That invasive species is the zebra mussel, and more recently another invader that was
likely carried to the lakes in the ballasts of ocean-going cargo ships, the quagga mussels.


Back on the Lake Guardian, Tom Nalepa says he’s seen the connection again and again.


“There’s no question that it’s related to zebra mussels and quagga mussels. In every area
that we’ve studied, regardless of the lake area, declines were happening a couple of years
after the quagga mussel or zebra mussel were first found, but that connection remains
elusive.”


Biologists thought the invasive mussels might have been filtering out all of the food the
diporeia eat, but when they find diporeia, they don’t appear to be starving. They appear
healthy. Now, scientists are wondering if there’s some kind of disease or toxin spread
by the mussels that’s wiping out the diporeia.


Even if researchers learn why the diporeia are disappearing, there might be nothing that
can be done to help. Some scientists worry that the decline of diporeia and other
organisms at the base of the food chain might ultimately lead to a massive collapse of fish
stocks in the Great Lakes.


For the GLRC, this is Lester Graham.

Related Links

Invasive Fish Rears Ugly Head in Great Lakes

  • With its ability to breathe out of water and wriggle its way over land during dry spells, the media has dubbed the northern snakehead "Frankenfish." Its appearance in Lake Michigan is scary to scientists. (Photo courtesy of USGS)

A few weeks ago, a Chicago fisherman caused a stir when he found a northern snakehead fish. The discovery set off a frantic search to find out if yet another invasive species is threatening the Great Lakes. The Great Lakes Radio Consortium’s Jenny Lawton has this report:

Transcript

A few weeks ago, a Chicago fisherman caused a stir when he found a northern snakehead fish. The find set off a frantic search to find out if yet another invasive species is threatening the Great Lakes. The Great Lakes Radio Consortium’s Jenny Lawton has this report:


Just before Halloween, the so-called Frankenfish reared its ugly head… filled with sharp teeth… in Chicago’s Burnham Harbor on Lake Michigan. And it’s still a mystery as to just how it got there.


Although the snakehead is arare item in some Asian cuisines, there’s a more common suspicion amongst local experts and hobbyists. That snakehead was probably a pet that outgrew its tank, and instead of the traditional farewell down the toilet, it was set free in Lake Michigan. Free to eat through the Lake’s food web.


Local pet store manager Edwin Cerna says that’s why he stopped selling the fish years before they were banned by U.S. Fish and Wildlife. He remembers one day, when he was adjusting a tank, he accidentally got in between a snakehead’s lunch and its mouth.


“He bit me in the hand… made me bleed. It hurts. It’s got a nice strong jaw and that’s why it’s so dangerous because it can kill big fish, literally cut them in half. It’s almost like a big old killer whale, like a miniature version of it.”


But why on earth would anybody buy a vicious fish that can grow up to three feet long in the first place? Jim Robinett is with the Shedd Aquarium in Chicago. He says he’s a fish geek.


“I gotta say, as a little fish, when you first buy them, they’re really attractive; they’re neat little animals, but they eat like crazy. They’re voracious.”


Robinett knows not to be fooled by the little guys because what happens next is the perfect plot for a B-horror movie. He says the snakehead fish grows quickly, eventually eating everything in its tank. If it doesn’t die from overgrowing that tank, its owner might be tempted to dump it into a nearby body of water where it will keep eating its way up the food chain. Robinett says that’s the fear in Lake Michigan.


“They could potentially start picking off small salmon and lake trout, which is native to these waters here, they’re not real discriminating, they’ve been known to take things as large as frogs, some small birds, even small mammals that happen to get in the way there close to shore. They’ll eat anything they get their mouth on.”


Most hobby fish don’t last long in Chicago’s cold water. But the northern snakehead is different. The snakehead is native to northern Asia, and the Lake Michigan Federation’s Cameron Davis says that makes the fish feel right at home around here.


“It’s a lot like us Midwesterners, it just kind of hunkers down and… that’s part of the problem with the snakehead is that it can live under very extreme conditions. Which means it’ll out compete those other fish, and that’s a tremendous problem.”


Snakeheads have another edge on other species. The fish guard their eggs, giving their young a better chance of reaching maturity. But perhaps the most peculiar thing about snakeheads is that they can breathe. In addition to its gills, they have an organ that works like a lung and allows it to breathe air. It’s able to live up to three days as it uses its fins to wriggle across land in search of another body of water.


But looking down into the murky waters at Burnham Harbor, Davis says we shouldn’t run screaming yet. It’s not exactly a horror film scenario.


“I don’t think that the snakehead is going to come and grab our children out of schools and eat them or anything like that. But it is a problem for those of us who like to fish for yellow perch and whitefish and some of the things that make the Great Lakes so fantatstic, could really be threatened by this fish getting into Lake Michigan.”


Other invasive species cause an estimated 137-billion dollars of losses and damages in U.S. waterways each year. Cameron Davis says simply banning the local sale of fish like snakeheads hasn’t been enough to keep the Great Lakes safe.


“We’ve got to stop imports of these kinds of fish into the United States. We can’t protect the Great Lakes unless we’re checking these things at the door when they come into the country. It’s that simple.”


Davis is pushing for the passage of the National Aquatic Invasive Species Act. The bill would allocate a total of 174-million dollars to develop new technology for identifying and eliminating the invaders if and when they arrive.


So far, local authorities ahven’t found another snakehead near the banks of Lake Michigan, but Cameron Davis says the initial find just proves how hard it is to regulate what comes into the country’s largest body of fresh water.


Standing on the dock at Burnham Harbor, Davis looks out over the dark waters and shakes his head.


“It’s just an indicator that we’re in a race against time right now. Let’s hope that if there are more than one out there, that they haven’t hooked up.”


If they have, he says, it could truly be the stuff horror movies are made of… at least, for the other fish in the Great Lakes.


For the Great Lakes Radio Consortium, I’m Jenny Lawton in Chicago.

Related Links

Native Lake Species Fighting Back

  • Alewives washed up on Lake Michigan shores after the invaders' populations exploded, then crashed. Researchers have a difficult time predicting how invasive species will affect the balance of nature in the Great Lakes.

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders:

Transcript

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders.


Some of the exotic species that have caused major problems in the Great
Lakes have been around since the 1940’s and ’50s. For example, the sea lamprey found its way into the lakes through manmade channels. It’s a parasite that attacks lake trout and other large game fish. It devastated the lake trout fisheries. Only recently have efforts gotten the lamprey under control. It’s still out there, but it’s not decimating the lake trout population as it once was.


More recently, a big concern has been the zebra mussel. It hitchhiked its way to the Great Lakes in the ballast water of cargo ships. In the last couple of decades the zebra mussel has caused major changes in all the lakes except for Superior where it seems limited to the shallow and warmer bays.


David Jude is a researcher with the University of Michigan’s Center for
Great Lakes and Aquatic Sciences. He says the huge numbers of zebra mussels siphon through lake water like a giant network of filters. There are so many of them that water in the lakes is actually clearer.


“I think people tend to hear about the water clarity increases. ‘Ah, the water’s clearer,’ you know, ‘That’s great!’ But it’s not great, because there’s a lot of things going on in the water column.”


Things such as, algae converting the sun’s energy into more phytoplankton.
Small fish and tiny invertebrate animals called zooplankton eat the phytoplankton and then they become food for fish. But, the zebra mussels filter out a lot of the phytoplankton, stealing food from the native zooplankton.


David Jude says a couple of other invaders are also causing havoc at the base of the food chain in the Great Lakes. Instead of eating just the green phytoplankton, zooplankton invaders from the Black and Caspian Seas also eat their North American cousins.


“These are predators. And they feed on the zooplankton, our native zooplankton that is out there already. So, not only do we have the impact of zebra mussels removing algae which is a food for these zooplankton, now we’ve got two predators that have been introduced and both of those will eat zooplankton which would have been food for fish to eat.”


Besides the zooplankton floating around in the water column, a major food source for fish is in the sediment at the bottom of the lakes, and it’s disappearing. James Kitchell is with the University of Wisconsin – Madison. He says many different kinds of fish depend on a little creature called diaporeia, which have become scarce in many areas.


“It appears to correlate in general with an increases in zebra mussels. So, there’s the prospect that diaporeia is literally starving to death as a consequence of zebra mussels eating the available food, but when you look at the diaporeia, they appear to be healthy. They’re not skinny and look to be starving. So that doesn’t explain it.”


It’s a big concern because a lot of fish that anglers like, such as yellow perch, depend on diaporeia for food.


Besides the zebra mussels and the two zooplankton predators, a fourth invader is causing problems. Populations of the round goby, an ugly, aggressive feeding little fish from Eastern Europe, have exploded in the Great Lakes. The round goby scours the bottom, eating the eggs and larvae of native fish. The University of Michigan’s David Jude says as big of a problem as the invasive fish has been over the last several years. The round goby’s future might soon be curtailed a bit.


“We did SCUBA dives in Lake Erie, for example, we’d turn over rocks. Round gobys would tear out from under the rocks and we’d have small mouth bass following us around and they would ignore the round gobys. They didn’t know how to catch a round goby. But, because there’s so many round gobys now, they had to learn how to eat them or die. So, the predators are definitely learning how to eat round gobys.”


Other native fish are beginning to eat the exotics. The silver chub, which once nearly disappeared from the Great Lakes, is making a bit of a comeback feasting on zebra mussels. With each invader, the lakes ecosystems go through upheaval, and then find a new balance. But make no mistake. It’s a different balance. Nicholas Mandrak is a researcher at Youngstown State University. He says exotic species invading the Great Lakes will mean continued changes, and for people who fish the lakes, not many of the changes will be good.


“You’re not going to be able to catch as many species that you’re used to catching. You know, the native species are going to decline. The walleye are going to decline. So, I think the bottom line is the recreational and commercial fisheries are going to change in a manner that is negative to most people.”


Researchers, though, have learned to be careful about predicting how invasive species will affect the lakes. They’re often surprised by the intricacies of the food web and the ecosystems that support it. Throwing an exotic invader into the mix makes it that much more unpredictable, and it will likely get worse. Mandrak says they’ve been studying how global warming might affect the lakes. One scenario suggests 30 to 40 new exotic species from the South will make their way through manmade canals as temperatures rise. For the biologists, it’s a worrisome concept. For the Great Lakes Radio Consortium, this is Lester Graham.

NATIVE LAKE SPECIES FIGHTING BACK (Short Version)

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports.


Aquatic Species from Europe and elsewhere have hitchhiked to the Great Lakes in the ballasts of cargo ships for many years. A lot of them have upset the natural ecosystems of the lakes. Lately, though, some native fish are taking advantage of the invaders. Nicholas Mandrak is a researcher at Youngstown State University. He says a Great Lakes minnow that was once thought to have died out has recently re-emerged.


“And they’re eating zebra mussels. So, it looks like the increase
in silver chub is related to zebra mussels, so we finally found a native
fish that is benefiting from the zebra mussel.”


Other researchers say small mouth bass are beginning to prey on another invasive species, the round goby, which eats the eggs and larvae of fish native to the Great Lakes. The researchers say the benefits don’t outweigh the negative affects on native species. But it evens the score a little. For the Great Lakes Radio Consortium, this is Lester Graham.