Fish-Eating Bird Disrupting Food Chain?

The once near-extinct double-crested cormorant has made a dramatic comeback in the past few decades, and sport fisherman say the fish-eating birds are hurting their business. But as states move to limit their cormorant populations, there’s still no solid research that the birds are really to blame. The GLRC’s Gregory Warner reports:

Transcript

The once near-extinct double-crested cormorant has made a dramatic
comeback in the past few decades, and sport fisherman say the
fish-eating birds are hurting their business. But as states move to
limit their cormorant populations, there’s still no solid research that
the birds are really to blame. The GLRC’s Gregory Warner reports:


More states are joining the war on cormorants: oiling eggs to prevent
them from hatching, or shooting the birds. More than 11,000 of the
federally-protected birds were shot last year.


But there’s still no scientific proof saying birds compete with sports
fisheries. Jim Farquar is a biologist with the New York Department of
Conservation:


“We’ve not been able to detect declines in the fisheries at this point
in time. But that doesn’t mean that with a larger cormorant population
it won’t happen.”


At issue is diet. Cormorants eat whatever small fish are available,
leaving big game fish alone. In some regions, the birds eat almost
exclusively round gobies, an invasive species. Anglers believe that
cormorants disrupt the food chain, causing the numbers of larger fish to
decline.


For the GLRC, I’m Gregory Warner.

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Ten Threats: Luring the Lamprey

  • The sea lamprey, up close. (Photo courtesy of USFWS)

One of the Ten Threats to the Great Lakes is the decline of many of the native species. The lake trout has been in trouble from over-fishing and because of an invasive species called, the sea lamprey. Conservation agents use a pesticide to keep the lamprey down, but it’s expensive, and sometimes it kills other fish. Now, researchers have discovered a lamprey pheromone that could help the fight against the sea lamprey. Stephanie Hemphill has that story:

Transcript

In our next report in the series Ten Threats to the Great Lakes we hear about how a native
fish has been hurt by an invasive species that swam into the lakes through a canal. Lester
Graham is our guide through the series.


One of the Ten Threats to the Great Lakes is the decline of many of the native species.
The lake trout has been in trouble from over-fishing and because of an invasive species
called, the sea lamprey. Ever since it invaded the Great Lakes, scientists have been trying
to keep the invasive sea lamprey under control.


Conservation agents use a pesticide to keep the lamprey numbers down, but it’s expensive,
and sometimes it kills other fish. Now, researchers have discovered a lamprey
pheromone. They think the chemical attractant could be a big help in their fight against
one of the most destructive invasive species in the Great Lakes. Stephanie Hemphill
has that story:


The sea lamprey came into the Great Lakes through canals more than a hundred years
ago. The slimy parasites attach themselves to big fish and feed on them until they die.
Each lamprey can kill 40 pounds of fish in its lifetime.


Between sea lampreys and over-fishing, the big native fish, the Lake Trout, was wiped out
in the lower Great Lakes. Only a few survived in small pockets in Lake Huron. Lake
Superior is the only place Lake Trout survive in healthy numbers.


There’s an aggressive 15-million dollar a year program to keep sea lamprey numbers
down. Part of the effort is using a chemical called TFM that kills the lamprey.
Wildlife managers spread the lampricide in streams in the spring. It kills some of the
young lamprey as they swim down into the lake.


University of Minnesota biologist Peter Sorensen says he and other scientists noticed that
TFM kills not just the juveniles, but the larvae that live in the streambed too. They also
realized, after a stream is treated, very few adult lamprey come back to the stream to
spawn, or lay new eggs.


“And this led to an observation decades ago, which was key, that adult lamprey must be
selective in how they pick streams. They only pick a few, and if you remove the larvae
they don’t seem to go in there.”


Scientists suspected the larvae might play a role in the spawning migration of adults.
That might mean the larvae are putting out a pheromone that tells the adults it’s a good
place to spawn. Just one larva attracts a lot of adult lamprey, indicating the pheromone
is very potent.


It was up to Jared Fine to determine what the chemical is. Fine is a PhD student working
with Peter Sorensen. For two years he sifted through the water in tanks holding lamprey
larvae.


“Separating the different chemical compounds, testing them biologically, seeing which
ones have activity, coming back to the active ones, further separating them, and just
repeating this until you get down to the one or two or three compounds that have the
activity.”


Fine narrowed it down to three compounds. He purified them and gave them to a colleague in the chemistry department, Thomas Hoye. Hoye created a synthetic version of the most potent pheromone. He says it should be possible to produce it on a large scale, and that means it could be used to treat the
Great Lakes. The question is, how much would he need?


“You know, would it be a tank car load, would it be a football field, would it be a dump
truck? It’s none of those. Would it be a barrel? No. Is it a bucket-full? No. In
fact it’s only about 500 grams, that’s just one pound, would treat all that water for a
month.”


And that’s all it would take, because the lamprey only spawn for a month, but the
treatment would have to happen once a year. Peter Sorensen says when lamprey
approach a stream to spawn, their clock is ticking. They have a powerful urge to lay
eggs, and once they’ve done that, they die.


“They are driven animals. Frankly they’re kind of on autopilot and pheromones are
what’s driving that autopilot to a very large extent, and now that we’ve got it, I think we
can really powerfully use that to our advantage.”


Sorensen says fisheries managers could use the pheromone to attract more lampreys to
streams outfitted with traps.


“You know the key here is the fact that this pheromone is natural, safe, and should be
very inexpensive to add.”


Fisheries managers hope the pheromone will help reduce the cost of controlling the
lamprey and add a new weapon to their arsenal.


The news on lamprey couldn’t have come at a better time for wildlife managers
around Lake Superior. After years of relatively constant numbers, the lamprey
population jumped dramatically this year. Scientists say lamprey may be finding new
spawning grounds in the mouths of streams, where lampricide is less effective. They’re
hoping they can use the pheromone to draw the lamprey to traps further upstream.


For the GLRC, I’m Stephanie Hemphill.

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Study: Sturgeon Stocks Down Worldwide

A new survey by the Pew Institute for Ocean Science finds sturgeon populations are severely depleted throughout the world, including in the Great Lakes region. The Great Lakes Radio Consortium’s Erin Toner reports:

Transcript

A new survey by the Pew Institute for Ocean Science finds sturgeon populations are severely depleted throughout the world, including in the Great Lakes region. The Great Lakes Radio
Consortium’s Erin Toner reports:


Sturgeon are called “living fossils” because their bodies are virtually unchanged since the time of the dinosaurs. The only species native to this region is the lake sturgeon. Nancy Auer is a fish biologist with Michigan Technological University.


She says sturgeon populations in the Great Lakes dropped severely in the 1850’s because of overfishing and because dams were built that blocked migration routes. She says now there are only a couple of places where sturgeon are somewhat abundant.


“One is the St. Clair River area and Detroit River are and one is up in Lake Superior in the Portage Lake area and these stocks are some of the last ones that have free capacity to range throughout the Great Lakes system.”


Hour says the state of Michigan has closed all sturgeon fisheries in an effort to boost populations. Other Great Lakes states are developing lake sturgeon management plans.


For the GLRC, I’m Erin Toner.

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Little Fish, Big Fish: Which to Keep?

The common practice of throwing the little ones back could be harming future fish populations. The Great Lakes Radio Consortium’s Christina Shockley reports:

Transcript

The common practice of throwing the little ones back could be harming future fish populations. The Great Lakes Radio Consortium’s Christina Shockley reports:


Anglers and commercial fisheries are often only allowed to take fish that are larger than a certain size. So the smaller fish are left to reproduce. And researchers say that means their offspring will also be smaller, and not as healthy.


David Conover is a marine scientist at Stony Brook University. He says the larger fish are vital to the overall health of their species.


“The eggs that these big, old females produce tend to be of higher quality. The egg diameters may be a little larger, the yolk that is supplied to the eggs seems to be more rich, the larvae hatch at a larger size, they have a higher survival.”


Conover says fish populations can be harmed in as little as three or four generations. And it can take much longer for a population to rebound – if it can at all.


He says possible solutions could include different rules that protect larger fish, and new limits on where fish can be harvested.


For the GLRC, I’m Christina Shockley.

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Scientists Keep Tabs on Exotic Crab

  • Sightings of the Chinese mitten crab outside of its native habitat make some scientists uneasy that it will turn into an invasive species. (Photo courtesy of the California Department of Fish and Game)

Biologists are asking people to keep their eyes peeled for another potential invader into the Great Lakes. A Chinese mitten crab was found in the St. Lawrence River last fall. The Great Lakes Radio Consortium’s David Sommerstein reports:

Transcript

Biologists are asking people to keep their eyes peeled for
another potential invader into the Great Lakes. A Chinese mitten
crab was found in the St. Lawrence River last fall. The Great Lakes
Radio Consortium’s David Sommerstein reports:


Scientists aren’t sounding the alarm yet. One Chinese mitten crab found near Quebec City doesn’t constitute an invasion. But if they reproduce, the critters could spread quickly.


David MacNeill is a fisheries specialist with New York Sea Grant. He says one was found in Lake Erie in the 1970s, but didn’t proliferate. The mitten crabs spawn in salt water, so they don’t really threaten the upper Great Lakes. But the St. Lawrence River may be better habitat. Regardless, MacNeill says the discovery highlights problems with foreign ships exchanging ballast water before they enter the Great Lakes system.


“Inside ballast tanks on ships, they’re like giant tidal mud flats. When you empty all the water out, there’s this large mud layer. Some of these organisms can burrow into the sediment which is what the mitten crabs do.”


In January, the Coast Guard conceded its ballast discharge rules don’t always work. It said it must find new ways to keep foreign invaders out of the Great Lakes.


For the Great Lakes Radio Consortium, I’m David Sommerstein.

Related Links

Luring an Invasive Fish With Pheromones

A scientist has discovered a chemical compound that attracts
an invasive fish. The Great Lakes Radio Consortium’s Mike Simonson
reports that this could be a breakthrough in controlling harmful fish
populations:

Transcript

A scientist has discovered a chemical compound that attracts an invasive fish. The
Great Lakes
Radio Consortium’s Mike Simonson reports that this could be a break through in
controlling
harmful fish populations:


Eurasian ruffe were introduced in the Duluth-Superior harbor from ballast water of
ocean-going
ships in the 1990’s. Ruffe reproduced so quickly, they now make up 80 to
90-percent of the fish
population, squeezing out native fish. Now, they’re spreading eastward across Lake
Superior
toward the lower Great Lakes.


University of Minnesota Fisheries Professor Peter Sorenson says he’s isolated a
pheromone that
will cause the fish to cluster in great numbers of male ruffe who are tricked into
thinking it’s time
to mate.


“It causes a great deal of sexual arousal and excitement. So to help detect this
thing, I suppose
like a dog they get a little crazy and just start swimming around like crazy and
nudging and
inspecting the fish in the tank.”


Once they’re clustered, Sorenson says it may be possible to find a way to cut their
population.
Sorenson hopes to find a similar pheromone in carp and sea lamprey, other invasive
species
which threaten native fish in the Great Lakes.


For the Great Lakes Radio Consortium, I’m Mike Simonson.

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Bait and Switch in the Seafood Section?

You might not be getting what you paid for in the seafood section of your grocery store. The Great Lakes Radio Consortium’s Lester Graham reports… a new study has found some fish are being sold in the guise of others:

Transcript

You might not be getting what you paid for in the seafood section of your
grocery store. The Great Lakes Radio Consortium’s Lester Graham reports a new
study has found some fish are being sold in the guise of others:


A new study finds cheaper fish are being sold as ‘red snapper.’ Amy Moran at
the University of North Carolina is a co-author of the study published in
Nature
. She says DNA tests showed three-fourths of the ‘red snapper’
filets they tested from grocery stores were actually other species. Moran says
consumers are being deceived a couple of ways:


“The public perception of how common these species are is obviously influenced
by how common they appear to be on the marketplace. And if you go to the
grocery store and see Red Snapper everywhere and it’s $6.95 a pound, you can
rightly assume that it’s fairly common. But if what you’re getting is something
different, it’s going to lead to some public misapprehension of how common these
species are and that may at some level affect policy.”


Because less valuable fish are being reported as ‘red snapper’ catches,
fisheries managers are fooled into overestimating the population of the fish,
contributing to over-harvesting.


For the Great Lakes Radio Consortium, this is Lester Graham.

Saving the American Eel

  • Eel fisherman John Rorabeck near his home and fishery on Point Traverse, near Kingston on northeastern Lake Ontario. He says these waters were once practically boiling with eels. One night, he caught 3 tons of eels. Today he's lucky to catch one eel. (Photo by David Sommerstein)

For centuries, the American eel dominated the waters of parts of the Great Lakes. Only fifty years ago, the snake-like fish accounted for half of the biomass of Lake Ontario. Today, it has all but disappeared. Researchers and fishermen see the decline as a shrill warning about changes in climate and the environment. And they say now is the time to do something about it. The Great Lakes Radio Consortium’s David Sommerstein reports:

Transcript

For centuries, the American eel dominated the waters of parts of the Great Lakes. Only
fifty years ago, the snake-like fish accounted for half of the biomass of Lake Ontario.
Today, it has all but disappeared. Researchers and fishermen see the decline as a shrill
warning about changes in climate and the environment. And they say now is the time to
do something about it. The Great Lakes Radio Consortium’s David Sommerstein reports:


Before you say, who cares about a slimy critter like an eel, hear me out. Eels are
amazing.


They spawn in the Sargasso Sea – the Bermuda Triangle. But no one’s ever caught them
in the act.


“There is a mystery that we haven’t solved. We have never seen them spawn.”


After they’re born, they’re like tiny glassy leaves. They float thousands of miles north
and west on ocean currents. Then they wiggle up rivers and streams from Florida to
Quebec.


“The eel is a fish that we should be looking at very closely.”


They live up to 20 years in freshwater before they start the long journey to the Sargasso
to spawn.


The problem is their offspring are not coming back.


“A very important native species of the Great Lakes, that we’re at serious risk of losing.”


As you can hear, a lot of people are worried about the eel, and not just in the Great Lakes.
European eel young are down 99% from the 1970’s. The Japanese eel is down 80%. In
Lake Ontario, the fish is all but gone. And the people who rely on it feel like they’re
disappearing too.


(sound up of waves)


Just ask fisherman John Rorabeck. He grew up here by the lighthouse on Point Traverse,
a peninsula that juts out into northeastern Lake Ontario.


Rorabeck’s been fishing these waters for more than thirty years. Eels were his prime
catch. He points past the lighthouse.


“I remember when I started fishing there were nights on that south shore, the most fish
that was in there would be eels at certain times and there was literally tons of them on
that south shore. Now you could go back and you’ll find nothing.”


He stopped fishing eels three years ago because it just wasn’t worth it.


“That eel is telling man we better smarten up because this is happening all over the
world.”


Now Rorabeck dedicates his fishing time to science. He catches specimens for leading
eel expert John Casselman, who examines them in his lab.


“It is truly a crisis. A crisis of concern.”


Casselman’s a scientist at the Glenora Fisheries Station, run by the Ontario Ministry of
Natural Resources. In 1980, at a point on the St. Lawrence River in mid-summer, he
counted more than 25,000 eels a day. Last year, there were scarcely 20 a day.


Casselman ticks off a host of possible causes – overfishing, dammed-up rivers, erosion,
pollution, invasive species, and perhaps most troubling, a climactic change of cooling
ocean currents.


“There is an interrelationship between what’s going on in the ocean and the recruitment of
eels.”


And he says we’re mostly to blame. The problem is, Casselman and other researchers
don’t know exactly how all the factors relate or which is worse. And they say there’s no
time to find out. Last summer eel experts from 18 countries made an unusual statement.
In what’s now called the Quebec Declaration of Concern, they urged more action, not
more science.


“I’m a research scientist and of course, I love data. At this stage, you don’t want me.
Don’t ask me to explain what’s going on here because by the time I get it figured out, it
may be too late.”


The Great Lakes Fishery Commission has issued an emergency declaration of its own. It
represents commercial fishermen and anglers in the region. Spokesman Mark Gaden
says it’s calling on the U.S. and Canada to do everything they can to reduce eel deaths in
the Great Lakes.


“We’re committing ourselves, our resources to working to make the recovery of the
species a reality.”


Last month, the province of Ontario halted commercial eel fishing for the foreseeable
future.


(sound up at beach)


Fisherman John Rorabeck supports that plan. He stares out across the waters he’s trawled
for decades. He says he’s behind anything to bring the eel back to Lake Ontario for
future generations.


“And hopefully we can. But…I don’t expect to see it in my time. When I… (crying)
…when I think of all the times that we’ve had out in the lake and my forefathers and see
what’s happening here, it breaks you down.”


Rorabeck says when he thinks of the eel nearing extinction, he feels like he and his way
of life are becoming extinct too.


For the Great Lakes Radio Consortium, I’m David Sommerstein.

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States to Have More Control Over Goose Populations?

The U.S. Fish and Wildlife Service plans to give the states more power in reducing the resident Canada geese population. The Great Lakes Radio Consortium’s Karen Kelly has more:

Transcript

The U.S. Fish and Wildlife Service plans to give the states more power in reducing the resident
Canada geese population. The Great Lakes Radio Consortium’s Karen Kelly has more:


An estimated 3.2 million Canada geese have made permanent homes on lawns, farms, and airport
runways across the U.S.


Officials say the birds collide with aircraft, damage crops and pollute water supplies.


States traditionally needed a permit to get rid of geese.


But Ron Kokel, a biologist with U.S. Fish and Wildlife, says the new proposal would allow
communities to have more say in how the bird population is managed.


“It puts the decision on exactly what management technique the state or local authorities want to
use; it puts that decision more on the local level.”


The public has until October 20th to comment to the U.S. Fish and Wildlife Service on the
proposal.


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

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Estrogen Feminizing Male Fish

Research is finding that the hormone in birth control pills is getting into water and affecting the reproduction of fish. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

Research is finding that the hormone in birth control pills is getting into water and
affecting the reproduction of fish. The Great Lakes Radio Consortium’s Lester
Graham reports:


Researchers had already noted that fish near sewer plants were affected by the estrogen from birth
control pills that passes through a woman’s body. Further research for Fisheries and Oceans
Canada reveals that levels of estrogen even lower than found downstream of some U.S. sewer
plants can have dramatic effect on fish. Karen Kidd is the lead scientist.


“And what we’re finding is that the males are all becoming feminized. And
we’re seeing declines in numbers
in one of our minnow species as well.”


That minnow species has declined more than 95-percent. The scientists say if the estrogen in the
water is affecting the fish… there might be human implications as well.


For the Great Lakes Radio Consortium, this is Lester Graham.

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