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.

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Fish Detectives

  • The fish detectives (a.k.a. scientists who specialize in fishery genetics) survey the scene. (Photo courtesy of the Lake Erie Center)

On television, the CSI detectives make forensic lab work look glamorous. It’s a cinch for them to track a criminal by the DNA left behind at the scene. In real life, DNA is also a powerful tool for solving environmental crimes and mysteries. Rebecca Williams visits the Fish Detectives:

Transcript

On television, the CSI detectives make forensic lab work look glamorous. It’s a cinch for them to track a criminal by the DNA left behind at the scene. In real life, DNA is also a powerful tool for solving environmental crimes and mysteries. Rebecca Williams visits the Fish Detectives:


(Sound of gulls and reel being cast)


It’s midday, and it’s so hot the gulls are just standing around with their beaks open.


But Joe Al-Sorghali is still trying to get himself a fish dinner:


“Hopefully I can get a good amount of perch today… they’re not that fishy so they’re a really good catch.”


It takes a lot of these little fish to fill up a dinner plate. But that doesn’t stop Al-Sorghali from going after perch and walleye any chance he gets. A lot of people call Lake Erie the Walleye Capital of the World.


Fishing is a really big deal here. So it makes sense that Lake Erie’s also home to the Fish Detectives.


(Dragnet theme music)


The fish detective headquarters is tucked away on the edge of a quiet cove. The investigators at the Lake Erie Center are not wearing trench coats. They’re not even wearing lab coats. This crew of laid-back lab techs and grad students comes to work in jeans and T-shirts.


Carol Stepien heads up the fish detective squad. She says they solve lots of cases of mistaken identity.


Take the Case of the Fried Perch.


Last year the detectives got a call from a TV station in Milwaukee. The news crew was suspicious that the fried local perch on restaurant menus wasn’t really local.


Stepien says she asked the news station to send her some frozen filets.


“So instead they sent their news crew out into restaurants and had their news crew eat the fish and put a little bit of the breaded, cooked fish in a plastic bag and froze those and sent them to me. We were pretty shocked to get those in our laboratory. We didn’t know if we could get DNA from breaded, fried material like that.”


But Stepien says they scraped off the breaded coating… and they actually were able to extract DNA from the little bits of cooked fish.


“And we found that about half of those fish were yellow perch from Europe.”


Stepien says it’s gotten more common for fish brokers to import yellow perch from outside the U.S. because it’s cheaper. She says even though the foreign perch might taste the same when they’re deep-fried… a close look at the DNA of the European yellow perch reveals big differences from Great Lakes yellow perch.


“They probably could be called freshly caught lake perch, but they were certainly frozen and didn’t come from any local lakes, they didn’t come from the Great Lakes. Instead they came from overseas.”


Stepien’s team will tackle any sort of mystery, as long as it involves gills and fins.


Lately they’ve solved cases of home invasion. That is, invasions by exotic species that’ve gotten into the Great Lakes. The scientists can track the invaders by their DNA fingerprints, and find out where they’ve been.


Joshua Brown is a Ph.D student at the lab. He’s been tracking the round goby. It’s a fish native to Europe. Scientists say it caught a ride to the Great Lakes in the ballast tanks of ocean going ships. It’s been crowding out native species.


“We’re going to find somebody to point the finger at, as it were. We’ve found evidence they came from the northern portion of the Black Sea, right around one of the major ports.”


That port is in Ukraine. Even though they’ve found the culprit, Brown says there’s not much governments can do, because everyone’s guilty.


“I don’t think you could really sue a nation for you know, not keeping their species under wraps. If so, we’d be open for a lot of lawsuits too – we export almost as many as we import.”


But Brown says knowing exactly where a foreign species comes from might help keep the door closed to future invaders from that same region.


Whether it’s a case of consumer fish fraud or defending the home turf from invaders, there’s one bottom line for these detectives. They want to find out as much as they can about native fish so they can keep them from going belly up.


For The Environment Report, I’m Rebecca Williams.

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Yellow Perch Making Resurgence?

A popular fish might be making a comeback in the upper Great Lakes. Yellow perch were once a favorite catch for sport and commercial fishermen, but their populations crashed in the 1990’s. Biologists say new surveys in Lakes Huron and Michigan have found huge numbers of young perch. The GLRC’s Peter Payette reports:

Transcript

A popular fish might be making a comeback in the upper Great Lakes.
Yellow Perch were once a favorite catch for sport and commercial
fishermen, but their populations crashed in the 1990’s. Biologists say
new surveys in Lakes Huron and Michigan have found huge numbers of
young perch. The GLRC’s Peter Payette reports:


A survey of Lake Michigan found more perch were born last year than in
the best years on record. Two or three times as many.


Recent studies of perch in Lake Huron’s Saginaw Bay have shown
similar results. It’s not clear why fish numbers would suddenly
skyrocket. Weather is believed to be one factor.


Dave Fielder is a biologist with the Michigan DNR. He says perch in
Lake Huron have also benefited from the decline of alewives, which are
an invasive species.


“We’ve known for a long time that alewives are formidable predators and
competitors on newly hatched yellow perch fry.”


Fielder says most of the newborn perch are not surviving so the adult
population in Saginaw Bay has not grown. He says it may be too many
perch have been born and there’s not enough food for them all.


For the GLRC, I’m Peter Payette.

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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.

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Cormorant-Killing Policy Ruffles Feathers

  • Cormorant populations have risen exponentially from their previously dismal numbers. (Photo courtesy of the NOAA)

Across the Great Lakes region, the recovery of the cormorant
is booming. But some anglers and resort owners think the cormorants are eating too many of the fish that people like to eat. In some areas, wildlife managers have resorted to killing cormorants on popular fishing lakes. In one case, critics say there’s not enough evidence to justify the killing. The Great Lakes Radio Consortium’s Stephanie Hemphill reports:

Transcript

Across the Great Lakes region the recovery of the cormorant is booming. But some anglers and resort owners think the cormorants are eating too many of the fish that people like to eat. In some areas, wildlife managers have resorted to killing cormorants on popular fishing lakes. In one case, critics say there’s not enough evidence to justify the killing. The Great Lakes Radio Consortium’s Stephanie Hemphill reports:


Larry Jacobson is the third generation in his family to run the Hiawatha Beach Resort on Leech Lake, about two hundred miles north of Minneapolis. Three years ago, on fishing opener weekend, all of his twenty-one cabins were full. This year, he had no guests. Jacobson says the word has spread that fishing is down on Leech Lake. He blames the cormorants. The birds nest on a small island in the south end of the lake. Eight years ago, there were fifty nests; last year, there were two thousand five hundred.


“The cormorants eat about a pound fish a day. The way the population was just exploding out there, you could see writing was on the wall, that this was really going to make dramatic impact.”


Jacobson says his guests are still catching big walleye, but the smaller, pan-sized walleye are getting hard to find.


There are several reasons why the walleye population might be down, but Jacobson and other business owners blame it on the cormorants, and they’ve asked the Department of Natural Resources to do something about the birds.


“Leech needs to be maintained as high quality fishery. There’s such an economic impact to the area from walleyes, that if you don’t maintain it that way, everyone’s going to be suffering.”


(Sound of boat motor)


Resource officials are responding to the resort owners’ concerns. The Leech Lake Band of Ojibwe owns the island. John Ringle is wildlife manager for the tribe.


“Okay we’re headed right at Little Pelican Island right now.”


Little Pelican Island is about three acres of sand and scruffy shrubs. Hundreds of cormorants cover the shore. Ringle says they fish out here in the open waters of Leech Lake.


“They’re omnivorous so they’re eating all sorts of different varieties of fish. Right now they’re probably eating large numbers of perch.”


Ringle is working with state and federal agencies to reduce the number of cormorants nesting here, eating fish, and crowding out other birds, such as the endangered common tern.


Normally, cormorants are a federally protected bird, just like eagles. That’s because they were almost wiped out by the insecticide DDT before it was banned in 1973. But a new rule allows resource officials to harass and even kill cormorants where they’re damaging other wildlife.


This summer, workers are sitting in hunting blinds on Little Pelican Island, shooting cormorants. They use air rifles to make as little noise as possible, so the other cormorants aren’t spooked away.


So far, they’ve killed more than two thousand birds. They plan to leave about five hundred nesting pairs alive. Ringle says nobody’s happy about shooting cormorants, but he says he thinks it’s necessary.


RINGLE: “My philosophy is that as mankind utilizes the resource, we have to manage them, we’re not in finite supply.”


HEMPHILL: “Do you think we know enough to manage them?”


RINGLE: “Not really. I think the public is demanding action prior to any conclusive study being conducted.”


And that’s a big problem for Francie Cuthbert. She’s a professor and cormorant researcher at the University of Minnesota. Cuthbert says the agencies that want to cut down the cormorant population skipped an important part of the management process: finding out what’s actually happening on Leech Lake.


“They’re really being driven by complaints from citizens and resort owners who are concerned about local economics, and who just don’t like the birds; they’re afraid of the numbers. If we responded to all natural resources conflicts this way, we’d be in a state of chaos.”


Cuthbert says even with the cormorants’ dramatic comeback since the days of DDT, there still aren’t as many as there were a hundred years ago. She says rather than kill cormorants, wildlife officials should try to boost the number of fish.


The state of Minnesota is working on that. It’s stocking Leech Lake with walleye for the first time this year. Conservation officials are studying some of the birds they killed to find out what they’re eating. And the state is also limiting what size of walleye anglers can catch so the fish can recover.


That makes resort owners like Larry Jacobson nervous, because he says a lot of anglers don’t like the limits. But at least he’s glad someone’s doing something.


“The fishery is a business, there’s no question about that. If you want to sustain our economy in this area, you’ve got to manage the lake.”


Workers will continue shooting cormorants occasionally through the summer. And the control effort could continue. Experts say it’ll take several years for the fish to recover enough to draw anglers back to the lake.


For the GLRC, I’m Stephanie Hemphill.

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Gobies Send Toxins Up the Food Chain

New research is showing that a foreign fish might be aiding the transfer of toxic substances into sportfish populations. The Great Lakes Radio Consortium’s Mark Brush has more:

Transcript

New research is showing that a foreign fish might be aiding the transfer
of toxic substances into sportfish populations. The Great Lakes Radio
Consortium’s Mark Brush has more:


Fish such as bass, trout, and walleye normally eat small native fish.
Now, these large sportfish have learned how to eat a new foreign fish – round
gobies. The gobies can contain toxic pollutants because they feed on
zebra mussels. And because of the way zebra mussels feed they can take up
a lot of pollutants like PCBs.


David Jude is a research scientist at the University of Michigan. He’s
been studying fish living near polluted areas.


“Yes, a lot of sportfish are eating round gobies, we found them in a lot of
predators we looked at in the St. Clair River – perch, brown trout,
walleyes – so the possibility of transferring PCBs into a
lot of the sportfish that people catch is certainly real.”


Jude says he hopes his research will determine ways to control goby
populations where they’ve become a problem.


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

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.

Fed Bill to Allow Cormorant Hunting

In recent years, the double-crested cormorant population has
exploded. And commercial fishermen say their business has suffered as a
result. The Great Lakes Radio Consortium’s Karen Kelly reports on a
new federal bill intended to reduce the population of this controversial
bird:

Transcript

The numbers fo bass and perch in the Great Lakes have declined. And many say the cormorant is to

blame. Now New York congressman John McHugh and Minnesota representative Collin Peterson are

proposing a solution. McHugh says they want to give states the option of creating a hunting season

for cormorants.


“The cormorant population is at an all-time high and I think most people who are even a

disppassionate, casual observer can understand that the cormorant population is having a

devastating effect on the fisheries and on the general environment.”


However, the National Audubon Society opposes the measure. They say the birds are protected under

the Migratory bird treaty act. The bill has been sent to the House committee on Resources. McHugh

hopes to have public hearings on the issue next spring.


For the Great Lakes Radio Consortium, I’m Karen Kelly.