Tag: native

Weevils vs. The Mile-A-Minute Weed

  • The mile-a-minute weed (Photo courtesy of the USDA)

Sometimes biologists fight foreign
pests with other foreign animals. But that
can be risky because it can create a bigger
problem than the one it’s supposed to solve.
Sabri Ben-Achour reports on one of the latest attempts to stop a weedy pest:

Transcript

Sometimes biologists fight foreign
pests with other foreign animals. But that
can be risky because it can create a bigger
problem than the one it’s supposed to solve.
Sabri Ben-Achour reports on one of the latest attempts to stop
a weedy pest:

On farms, backyards, and rights of way up the Eastern Seaboard a pointy leaved thorny
newcomer is becoming increasingly visible. It’s called mile-a-minute weed.

Bob Trumbule is an entomologist. He leads me through a stream valley north of
Washington DC where blackberries and small trees are being swallowed up by this
invasive vine.

“So now we’re getting into the mile-a-minute here. Basically what it does it, it’s an
annual vine, it grows up and over plants, it smothers them, out competes them for
sunlight, and weighs them down.”

The weed is native to Eastern Asia: China and Japan. It was introduced accidentally in
Pennsylvania in the thirties. From there, it’s spread to seven other states. It prevents new
trees from sprouting in forests. But back in Asia, it’s not a dominating species like it is
here.

Judith Hough-Goldstein is a professor at the University of Delaware.

“Part of the reason is because it doesn’t have anything that’s feeding on it. It’s gonna be
without its predators so it can out-compete other plants.”

Over several years, biologists searched for something that would eat the vine. They
found a tiny, black weevil in China. It feeds on the plant and lays it’s eggs there, keeping
things in check – in Asia.

“Here are the weevils. I’m gonna give you a glimpse of them here in the cup. They look
almost like little ticks. I’m gonna put them down here in the mile a minute weed patch,
and basically what they’ll do – they’re tough little guys – they’ll climb around and in the
past experience have started to feed almost immediately.”

Up close, they look like little anteaters, poking around the leaves with long snouts.

This may sound risky. There are lots of examples where similar approaches have gone
wrong. A parasite was introduced in North America to control gypsymoths. It attacked
native silkmoths. Mississippi catfish farmers used Asian carp to control algae. They got
loose and are taking over the Mississippi River system and threatening the Great Lakes.

And Trumbule admits nobody knows for sure exactly what might happen.

“Any scientist that might say otherwise is not being honest with themselves or the person
asking the question.”

But he says a lot’s been learned since the days when any scientist could introduce a
species on a whim. These days, exhaustive testing and federal permits are required
before anything is released.

That’s why for almost ten years Judith Hough-Goldstein has been trying to determine if
the weevil would eat anything else. Tests were conducted in a U.S. Department of
Agriculture ‘quarantine facility’ with sealed windows and its own re-circulated air supply.

“So what we found was that, in fact, this particular weevil is extremely host specific. The
insect has evolved to depend on the plant.”

So much so that the weevils and larvae actually starved to death rather than feed on other
plants.

In field tests in New Jersey and Delaware, the weevils have decimated mile-a-minute
weed. Some researchers say it’s the most impressive biocontrol they’ve worked with.

For The Environment Report, I’m Sabri Ben-Achour.

Related Links

Westward Ho for the Ash Borer

  • Adult emerald ash borer (Photo by David Cappaert, Michigan State University, courtesy of the Michigan Department of Agriculture)

The emerald ash borer has eaten through
millions of trees in the US and is spreading
west. Erin Toner has more:

Transcript

The emerald ash borer has eaten through
millions of trees in the US and is spreading
west. Erin Toner has more:

For six long years, the tiny metallic-green emerald ash borer has been a killing machine,
starting with millions of ash trees in Michigan and Canada, and then munching its way
into 10 states.

It was recently discovered in Missouri, and now, it’s in Wisconsin.

The prognosis is not good.

Darrell Zastrow is with the Wisconsin Department of Natural Resources.

“Our forests are not typically resilient against non-native species and that is true for
the emerald ash borer. It is generally considered to be a poster child for invasive
species.”

Officials in Wisconsin are doing what everyone else has done – restricting the movement
of firewood and telling people how to protect their trees.

Some promising treatments to fight the emerald ash borer are being tested, but so far,
nothing has worked at keeping the insect from spreading west.

For The Environment Report, I’m Erin Toner.

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Keeping a Big Fish From Butting In

  • Asian Carp can grow up to 110 pounds (Photo courtesy of the US Fish and Wildlife Service)

There are invasive fish swimming their
way toward the Great Lakes. If they get in,
they could swallow up a multi-billion dollar
sport fishing industry. Mark Brush reports,
officials are investing millions of dollars
to keep Asian Carp out of the Great Lakes:

Transcript

There are invasive fish swimming their
way toward the Great Lakes. If they get in,
they could swallow up a multi-billion dollar
sport fishing industry. Mark Brush reports,
officials are investing millions of dollars
to keep Asian Carp out of the Great Lakes:

Asian Carp were imported by fish farms in Mississippi and Arkansas to control algae.
But the fish escaped during floods. They swam out of the fish ponds, and into the Mississippi
river. And they’ve been moving north ever since.

(sound of boats)

Thad Cook is on a tributary of the Mississippi River in Illinois. This river is more than
400 miles upstream from where Asian Carp first escaped the fish farms.

Cook is looking
for two types of Asian Carp known as Silver and Bighead Carp. It turns out t’s not hard to find them. He dips an electrified pole into the water – and the fish jump right out of the
river and into the boat.

(sound of fish flopping in boat)

Cook is with the Illinois Natural History Survey. His group, along with several others,
has been making trips like this one for years. They’ve been keeping a close eye on where
the fish are going. He takes a guess at how big this fish is.

“No he’ll go… uh.. he’s probably…”

“Hold him out there Jimmy!”

“Yep, six, seven, eight, nine, ten pounds.” (Laughter)

His fish story could have gone a lot further. Some types of these Carp can get up to a
hundred pounds. There aren’t many fish that can compete with an appetite like that.

Biologists are finding that these carp are pushing native fish species aside as they spread
north through the Mississippi River system. And some fear it’s only a matter of time
before they swim their way into the Great Lakes.

David Jude is a fisheries biologist with the University of Michigan.

“I’m very concerned about what impact they would have in the Great Lakes because
they’re planktovores which means they filter zooplankton from the water column. And, they’re just huge fish. And so they have the potential for having
a tremendous impact on our ecosystems.”

He says the silver and bighead carps are filter feeders. They pass up eating smaller fish –
and head straight for the bottom of the food chain.

Jude says if Asian carp get in, it’ll make a bad situation worse. The Great Lakes are
already losing zooplankton from other invasive species. Asian Carp could
destroy a 4 billion dollar a year sport fishing industry.

(sound of canal)

And here is where the battle line is being drawn. The fish have been spotted thirty miles
downstream from this spot on the Chicago Ship and Sanitary Canal. A century ago,
engineers blasted through solid rock to connect the Great Lakes with the Mississippi
River system.

Chuck Shea is with the U.S. Army Corps of Engineers.

“Any type of fish that would want to move between Lake Michigan and the Mississippi
river basin – has to pass through the Chicago Sanitary and Ship Canal – there’s no other way to swim through. So, they have to come through this body of water we’re standing in front
of right now.”

Shea is in charge of the construction and maintenance of two electric fish barriers along this canal.
When this barrier is online, machines will pulse electricity into the water. The electric current shocks
the fish – making them swim away.

This barrier hasn’t been turned on yet. There have been delays due to funding shortages. And they’re still
doing safety testing with the Coast Guard.

Right now, the only thing that would keep the carp from getting into the Great Lakes is a temporary electric
barrier built six years ago.

The good news is that there still seems to be a little time. Biologists say, so far, Asian Carp haven’t moved any
closer than thirty miles from the barrier for the last couple of years.

For The Environment Report, I’m Mark Brush.

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A Silver Bullet for Zebra Mussels?

  • Zebra mussels were discovered 20 years ago, and have since spread across the country (Photo courtesy of the US Fish and Wildlife Service)

Researchers say they’ve found something
that will kill invasive zebra and quagga mussels.
The mussels got into the US in the ballast of
foreign ships. Since then they’ve spread throughout
the country. Rebecca Williams reports:

Transcript

Researchers say they’ve found something
that will kill invasive zebra and quagga mussels.
The mussels got into the US in the ballast of
foreign ships. Since then they’ve spread throughout
the country. Rebecca Williams reports:

So, let’s say you have a nasty pest, an invasive species. Then someone says, we can get rid of that
pest and it looks like there’s no environmental downside.

“It kinda sounds like snake oil. But it’s true.”

That’s Dan Molloy with the New York State Museum lab. He’s come up with a
way to kill zebra and quagga mussels.

Molloy says a strain of common bacteria is toxic to zebra and quagga
mussels. And, even if the bacteria are dead, they can still kill the
mussels.

“You know maybe horror stories of people applying biocontrol agents. And it
had effects they didn’t anticipate. We’re applying dead cells. And they’re
just as effective live or dead.”

It’s great news for power plants, because the mussels clog up intake
pipes.

But it’s not clear if the bacteria can kill mussels in open water.

For The Environment Report, I’m Rebecca Williams.

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New Ship Has Balance Without Ballast

  • A diagram of the ballast-free ship (Photo courtesy of Professor Michael Parsons)

Cargo ships move sea life around the world.
Moving aquatic life from one port to another can cause
environmental havoc. Lester Graham reports there’s a
new idea that could nearly eliminate the problem of
transporting sea life to foreign ports:

Transcript

Cargo ships move sea life around the world.
Moving aquatic life from one port to another can cause
environmental havoc. Lester Graham reports there’s a
new idea that could nearly eliminate the problem of
transporting sea life to foreign ports:

There is an invasion of every major port on the globe.

“Today, the world’s shores are under attack. Armies of aliens are secretly invading our coasts.”

If this video, Invaders from the Sea, from the International Maritime
Organization sounds a little over-dramatic, it’s really not. Invaders from far-flung
corners of the world are brought in by commerce. In their travels, cargo ships pick up the
hitchhikers.

Those hitchhikers can be fish, mussels – aquatic bugs of all kinds. They can become
pests. Out-compete native species for food and space. They can destroy the
native ecosystems and often damage the economic well-being of people.

Here’s how it happens. Ocean-going cargo ships dock at a foreign port. They pump in
water for ballast to keep the ship stable. They also pump in some of the living things in
the water. When they arrive at the destination port, they can pump out that water and
the critters that were sucked up with it.

In the US, ports from Chesapeake Bay to San Francisco have been invaded. But,
the Great Lakes have been hit especially hard by invasive species.

Michael Parsons is a professor of naval architecture at the University of Michigan. He
says when foreign ships were able to come in from the Atlantic and travel as far as
inland as Duluth, Minnesota; they brought a lot of invaders with them.

“With the opening of the St. Lawrence Seaway in the ‘50’s, that led to increased
introduction of non-indigenous species such as the zebra mussel, and the round goby, and
the ruffe, and the various smaller creatures that have been brought in to the Great Lakes.”

Those creatures have damaged the ecosystem of the Great Lakes. And they’ve cost the economy.
By one Environmental Protection Agency estimate about five-billion dollars a year.

Parsons and his colleagues have been working to design a ship that has no need for
ballast. In the lab, a scale model has been tested in a long pool. Instead of pumping
water in and out of the ballasts, the water would flow through big
tubes that run the length of the ship.

“And so, that’ll create a slow flow through these trunks so that they’re always swept
clean of foreign water.”

“A ship like that is just what we need in the Great Lakes.”

Andy Buchsbaum runs the Great Lakes office of the environmental group, the National
Wildlife Federation.

“If you eliminate the need for ballast water altogether, then you’re eliminating the vast
majority of invasive species introductions that come in through the discharge of ballast.”

The ballast-free ship design is creating some excitement. Even the shipping industry is
paying attention because the ship also is more fuel efficient.

If someone decides to actually build the ballast-free cargo ship, it’ll be a while before
the first one is on the high seas.

Allegra Cangelosi has been working on the ballast and invasive species problem for
close to a decade. She’s a policy analyst with the Northeast-Midwest Institute.

“I think it’s a wonderful development. I don’t think there’s going to be any one answer
for all ships plying all waters throughout the globe. However, the more good answers
that are out there to choose from, the better for the environment.”

Some of those choices are filtering ballast water or killing organisms in the ballast with
chemicals. Those systems are expensive. And since fuel isn’t getting any cheaper, that
might make a more fuel-efficient ballast-free ship attractive.

For The Environment Report, this is Lester Graham.

Related Links

Big Ships Required to Flush

  • A ship discharging its ballast water (Photo courtesy of the US Geological Survey)

Ships should be bringing in fewer unwanted
pests into the Great Lakes. Both Canada and the
U-S are now requiring ships to flush out their
ballast water tanks before entering the lakes.
Tracy Samilton reports:

Transcript

Ships should be bringing in fewer unwanted pests into the Great
Lakes. Both Canada and the U.S. are now requiring ships to flush out their
ballast water tanks before entering the lakes. Tracy Samilton reports:

Ships need to take on ballast water to keep them stable. When they pump in
water from freshwater foreign ports, they also suck up pests.

Since 2006,
Canada has required ships to flush their tanks with salty ocean water
before entering the Great Lakes. The U.S. adopted the requirement at the
start of this year.

Collister Johnson is with the U.S. side of the St.
Lawrence Seaway, which connects the Atlantic Ocean to the Great
Lakes. He says the rule will eliminate almost 99% of freshwater
pests in ballast tanks.

“If they’re exposed to salt water, especially full strength sea water, they
are effectively killed.”

Samilton: “Why didn’t we do this before?”

Johnson: (laughs) “I don’t know.”

It won’t completely eliminate the problem because some aquatic pests can
still survive in the sediment in the bottom of ballast tanks.

For The Environment Report I’m Tracy Samilton.

Related Links

Watching Artificial Wetlands

  • Natural wetlands that are developed are supposed to be replaced by man-made wetlands somewhere else. (Photo by Lester Graham)

More than half of U.S. wetlands have been drained for
development, farmland, and other purposes. That’s 100
million acres now dried up. The Bush administration has
continued “no net loss” policy of any more wetlands.
So, when someone wants to drain a marsh or a swamp for,
say, a new housing development, they’ve got to build a man-
made wetland to replace it. But a new study is finding that
most of those man-made wetlands aren’t doing very well.
Julie Grant reports:

Transcript

More than half of U.S. wetlands have been drained for
development, farmland, and other purposes. That’s 100
million acres now dried up. The Bush Administration has
continued a “no net loss” policy of any more wetlands.
So, when someone wants to drain a marsh or a swamp for,
say, a new housing development, they’ve got to build a man-
made wetland to replace it. But a new study is finding that
most of those man-made wetlands aren’t doing very well.
Julie Grant reports:


(Sound of truck stop)


These 18-wheelers are lined up on a huge black parking lot
behind a truck stop off Interstate 80. Looking at it, this
wouldn’t seem like the ideal place to create a wildlife area.


But wetland ecologist Mick Micacchion has chosen this place
to show that man-made wetlands can be successful.
At the edge of the parking lot, we walk down into some
brush. The ground is mostly even, there’s no big ditches… just
some gentle slopes. The weather’s been dry the past few
weeks. But water starts seeping into my shoes:


(Mike:) “You getting wet?”


It might be bad for our shoes, but saturated soil is a good
sign for a wetland, and so are a lot of the plants we’re seeing.


As we walk, Micacchion stops at plant after plant…
Impatients, monkey flower, and lots of grass-like plants called
sedges. These all grow in wet soil:


“So even in sedge community, we’re seeing some diversity.
Which is unusal in a wetland that’s only been constructed for
a few years. But it tells you some good things are going on
here.”



Checking out what’s going on at wetlands like this one is a
new job for Micacchion. He works for the state government.
Federal officials used to take authority over wetlands as part
of the Clean Water Act. But a U.S. Supreme Court decision
six years ago took away some of that federal authority, and
left responsibility for these kinds of isolated wetlands up to
states.


That’s why Micacchion is studying man-made wetlands for
the Ohio EPA: to assess how well the state program is
working.



Wetlands that work are not only good for wildlife…they
provide a holding area for water when there’s heavy rain.
That helps prevent flooding. It also gives polluted sediments
time to drop out of the water, so it’s filtered, which means
it’s cleaner by the time it drains into streams, rivers and
lakes.


But this story of a successful man-made wetland is the
exception. A study Micacchion’s is conducting is finding that most are in fair
or poor condition.


The loss of functioning wetlands can lead to more flooding
and polluted waterways.


Micacchion says when developers drain natural wetlands,
they often don’t understand how to build artificial wetlands to
replace those original systems.


Our next stop is a good example of that. We pull into a parking lot just behind a busy street
of car dealerships. One company drained a wetland back
here to build an access road. And to replace it, they built a
pond.


Tom Wysocki walks out of the car dealership to see what
we’re up to out on his property:


“Is there someone in your office, who I mean, is this your
Beliwick in the office?”


“It would come to my desk.”


“You’re the wetlands expert at Klaben Ford.”


“I’m the expert on everything.”


Originally, this site might’ve correctly designed for a wetland. But
Wysocki decided it didn’t look right to him because it wasn’t
holding water. So he had it dug again to make a pond.


He and the actual wetlands expert definitely have a different
idea about what a successful wetland looks like. Micacchion
says a pond isn’t a wetland:


“Usually with natural wetland systems, the slopes
are very gentle. And you have to walk out maybe 15-20 feet
before you get a foot deep of water. Here, you could step in
and maybe immediately be in a foot to two feet of water. And then, the deep
water it becomes difficult for certain plants to grow.”



The area is dominated by a couple of kinds of plants. But
Micacchion says they’re both invasives. And they’re
crowding out the native wetland plants. Native plants would
provide habitat for wildlife:


“This is all reed canary grass. The biggest problem with it, it
comes in, and you can see it gets very thick. It’s pretty much
only species you see growing with just a few other things you see
poking their heads up here and there. This eliminates some
of diversity we might see otherwise.”


Micacchion says his study is finding that this is pretty typical.
Even if a developer starts out with right kind of plan,
somebody can make an arbitrary decision that defeats the
original purpose. But Micacchion says it doesn’t have to be
that way. Man-made wetlands can work if they’re designed
by ecologists and engineers who understand the details of
what makes natural wetlands so useful.


His office is creating wetlands guidelines. They want
developers to understand the natural wetlands they’re destroying and what they need to do to replace them.


For the Environment Report, I’m Julie Grant.

Related Links

Virus Killing Great Lakes Giants

  • Fishing guide Rich Clarke of Clayton, NY, is famous for muskie hunts. He's worried so many adult muskies are falling victim to VHS. (Photo courtesy of Rich Clarke)

Fall is when avid anglers flock to the Great Lakes for one of the most
challenging freshwater catches: the muskellunge, or muskie. Some call it
“the fish of 10,000 casts.” This year’s muskie season is clouded by bad news
of a new fish disease and invasive species crowding muskie habitat. David
Sommerstein reports scientists are watching this top-of-the-food-chain
species carefully:

Transcript

Fall is when avid anglers flock to the Great Lakes for one of the most
challenging freshwater catches: the muskellunge, or muskie. Some call it
“the fish of 10,000 casts.” This year’s muskie season is clouded by bad news
of a new fish disease and invasive species crowding muskie habitat. David
Sommerstein reports scientists are watching this top-of-the-food-chain
species carefully:




It’s a cool afternoon as fishing guide Rich Clarke fillets the day’s catch:


“Went out, caught some northerns, a few bass, some jack perch. Had a
pretty good morning.”


Clarke’s specialty is hunting for muskies, 60 pound fish with a lot of fight:


“I mean, the rod screams, they yank, yank, and yank. It doesn’t come all that
often, but when it comes, it’s one of the most exciting things you’ll see when
you fish in fresh water.”


Clarke worries that magical hit might become even more rare. Since 2005,
several hundred of those prized muskies were found belly-up dead, victims
of viral hemorrhagic septicimia, or VHS.


(Sound of hose)


Clarke washes down his fillet table. He mutters VHS is just another non-
native organism threatening the muskie. There are already more than 180
invasive species in the Great Lakes-St. Lawrence River system:


“Everything from the goby to the , y’know, and weed species and all
sorts of stuff, spiny water fleas, you name it, all sorts of stuff that are not native to this
waterway that we have to deal with, and it changes the whole ecology.”


A new invasive species is found every six to nine months. Scientists can
barely keep up in understanding the impact on the native environment.




In a nearby bay of the St. Lawrence River in northern New York State,
Roger Klindt, John Farrell, and a crew drag a huge net through the water:


“We’ve got two people pulling it slowly through the vegetation just trying
to basically corral fish.”


This is called seining, getting a sample of all the fish that live here. Klindt
and Farrell have been doing this in the same marshy shallows for more than
20 years. And Farrell says what they’ve found this year is disturbing:


“Muskellunge numbers in the index are at their lowest levels on record since
we’ve been collecting data.”


Down from almost 50 in the spring spawning run of 2003 to just 4 this year.
Farrell’s a researcher with the State University of New York Environmental
Science and Forestry. He says this could be the result of VHS killing so
many adult muskies in their reproductive prime.




Yet another invasive species is also troubling, the round goby. It’s an ugly
little fish from Eastern Europe that breeds like crazy. Farrell and Klindt
count minnows flipping and fluttering in the seining net:


“15 black gins, 8 blunt nose, 5 spot tail.”


“I didn’t actually count things, I was just picking gobies.”


Farrell says they’ve found more round gobies in these marshes than ever
before:


“Which is a bit of a surprise to us.”


Now the muskie young have to compete with round gobies for food:


“How these species are going to respond to the presence of gobies is
unknown at this time, but they have high predation rates, they’re very
prolific, becoming extremely abundant, so the food web in this system is
shifting.”


This is what frustrates people who study invasive species. Once researchers
train their focus on one, like the fish disease VHS, another emerges to
confound the equation. Roger Klindt is with New York’s Department of
Environmental Conservation:


“Change happens, y’know, nothing stays the same forever. But when we
have invasive species and exotic species come in, the change is often so
rapid that native species can’t adapt to it.”


That talk makes anglers nervous. Peter Emerson’s been fishing around here
for years. In fact, he participated in a catch and release program that brought
muskie populations back to health in the 1980s:


“There was a real bonanza, til this virus showed up. I’m hopeful they don’t
go extinct.”


Biologists expect adult muskies that survived VHS will develop resistance to
the disease. But they fear the next generation won’t inherit the immunity,
causing more die-offs of one of America’s most prized freshwater fish.


For The Environment Report, I’m David Sommerstein.

Related Links

Ten Threats: The Earliest Invader

  • A bridge for a river... this portion of the Erie Canal crossed the Genesee River via an aqueduct in Rochester, NY. This photo was taken around 1914. (From the collection of the Rochester Public Library Local History Division)

The Ten Threats to the Great Lakes” is looking first at alien invasive species. There are more than 160 non-native species in the Great Lakes basin. If they do environmental or economic harm, they’re called invasive species. There are estimates that invasive species cost the region billions of dollars a year. Different species got here different ways. David Sommerstein tells us how some of the region’s earliest invaders got into the Lakes:

Transcript

We’re bringing you an extensive series on Ten Threats to the Great Lakes. The Great Lakes Radio Consortium’s Lester Graham is guiding us through the reports:


“The Ten Threats to the Great Lakes” is looking first at alien invasive species. There are more than 160 non-native species in the Great Lakes basin. If they do environmental or economic harm, they’re called invasive species. There are estimates that invasive species cost the region billions of dollars a year. Different species got here different ways. David Sommerstein tells us how some of the region’s earliest invaders got into the Lakes:


If the history of invasive species were a movie, it would open like this:


(Sound of banjo)


It’s 1825. Politicians have just ridden the first ship across the newly dug Erie Canal from Buffalo to New York.


(Sound of “The Erie Canal”)


“I’ve got an old mule, and her name is Sal. Fifteen miles on the Erie Canal…”


Chuck O’Neill is an invasive species expert with New York Sea Grant.


“At the canal’s formal opening, Governor DeWitt Clinton dumped a cask of Lake Erie water; he dumped that water into New York Harbor.”


Meanwhile, in Buffalo, a cask of Hudson River water was triumphantly poured into Lake Erie.


“In a movie, that would be the flashback with the impending doom-type music in the background.”


(Sound of ominous music)


It was an engineering and economic milestone, but a danger lurked. For the first time since glaciers carved the landscape twelve thousand years ago, water from the Hudson and water from the Great Lakes mixed.


(Sound of “Dragnet” theme)


Enter the villain: the sea lamprey. It’s a slimy, snake-like parasite in the Atlantic Ocean. It sucks the blood of host fish.


Within a decade after the Erie Canal and its network of feeders opened, the sea lamprey uses the waterways to swim into Lake Ontario. By the 1920’s and 30’s, it squirms into the upper Lakes, bypassing Niagara Falls through the Welland Canal.


What happens next is among the most notorious examples of damage done by an invasive species in the Great Lakes. By the 1950’s, the sea lamprey devastates Lake trout populations in Lake Superior. Mark Gaden is with the Great Lakes Fishery Commission.


“They changed a way of life in the Great Lakes basin, the lampreys. They preyed directly on fish, they drove commercial fisheries out of business, the communities in the areas that were built around the fisheries were impacted severely.”


The sea lamprey wasn’t the only invader that used the canals. Canal barges carried stowaway plants and animals in their hulls and ballast. In the mid-1800’s, the European faucet snail clogged water intakes across the region. The European pea clam, purple loosestrife, marsh foxtail, flowering rush – all used the canal system to enter the Great Lakes.


Chuck O’Neill says the spread of invasive species also tells the tale of human transportation.


“If you look at a map, you can pretty much say there was some kind of a right-of-way – railroad, canal, stageline – that was in those areas just by the vegetation patterns.”


Almost one hundred invasive species came to the Great Lakes this way before 1960. O’Neill says every new arrival had a cascading effect.


“Each time you add in to an ecosystem another organism that can out-compete the native organisms that evolved there, you’re gradually making that ecosystem more and more artificial, less and less stable, much more likely to be invaded by the next invader that comes along.”


(Sound of “Dragnet” theme)


The next one in the Great Lakes just might be the Asian Carp. It’s swimming up the Illinois River, headed toward Lake Michigan. Cameron Davis directs the Alliance for the Great Lakes.


“If this thing gets in, it can cause catastrophic damage to the Great Lakes, ‘cause it eats thirty, forty percent of its body weight in plankton every day, and plankton are the base of the food chain in the Great Lakes.”


The U.S. Army Corps of Engineers has installed an electric barrier in the Chicago Sanitary and Ship Canal that might stop the carp. But as long as the canals around the region remain open for shipping and recreation, it’s likely more invaders may hitch a ride or simply swim into the Great Lakes.


For the GLRC, I’m David Sommerstein.

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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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