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:
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
“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
Officials say a disease might be killing an invasive species of fish in Lake Ontario and the St. Lawrence River. The GLRC’s David Sommerstein reports:
Officials say a disease might be killing an invasive species of fish in Lake
Ontario and the St. Lawrence River. The GLRC’s David Sommerstein
Where the lake and the river meet, people have been finding dead round
“Dozens in some cases, hundreds of dead gobies that have been washing up on shores.”
Steve Litwiler is with New York’s Department of Environmental
Conservation. He says a change in water temperature or a poison could
cause the die-off, but initial sampling suggests some kind of disease.
“Is it a disease that could potentially affect other fish? Fortunately right
now the only fish that are dying appear to be the round gobies.”
If only the round gobies die, this could be a good news story. Round gobies
hitched a ride from Europe in the ballast of foreign freighters. They’ve
displaced native species across the Great Lakes by breeding faster and eating
other fishes’ eggs and young.
The Great Lakes is the largest group of freshwater lakes in the world. Preservation and usage of the Lakes is a hot issue for 2005. (Photo courtesy of michigan.gov)
This coming year will likely see some major policy decisions regarding the Great Lakes. Because the lakes stretch out along eight states in the U.S. and two provinces in Canada, getting all the governments to agree on issues is a long and sometimes trying process. But… those involved think 2005 will be the year that some real progress on Great Lakes issues will be made. The Great Lakes Radio Consortium’s Lester Graham recently talked with the Chair of the U.S. Section of the International Joint Commission, Dennis Schornack. The IJC deals with disputes and advises the U.S. and Canadian governments on issues regarding the Great Lakes:
This coming year likely will see some major policy decisions regarding the Great Lakes. Because the Lakes stretch out along eight states in the U.S. and two provinces in Canada, getting all the governments to agree on issues is a long and sometimes trying process. But those involved think 2005 will be the year that some real progress on Great Lakes issues will be made. The Great Lakes Radio Consortium’s Lester Graham recently talked with the chair of the U.S. Section of the International Joint Commission, Dennis Schornack. The IJC deals with disputes and advises the U.S. and Canadian governments on issues regarding the Great Lakes:
The International Joint Commission and the Government Accountability Office both have been critical of the U.S. government for not finding clear leadership on Great Lakes issues. Different agencies sometimes find their efforts overlap or conflict with others. At times, it seems there’s no organized effort to restore the health of the Great Lakes. Dennis Schornack says he thinks things were starting to get better because recently appointed U.S. Environmental Protection Agency Administrator Mike Leavitt took a real interest in the Great Lakes. But now Leavitt is leaving to become the new Health and Human Services chief.
“It’s going to be hard to beat the enthusiasm of Mike Leavitt. He spent literally about fifty percent of his time as EPA Administrator in the Great Lakes throughout. He was everywhere this past summer. But it does fall to the new administrator, whomever he or she may be; but in the meantime, the governors and mayors are proceeding forward on the priorities that they set over a year ago, and fleshing those out into very tight kinds of recommendations.”
Countless studies and reports on the Great Lakes point out one of the biggest threats to the lakes is invasive species. Those are foreign critters such as zebra mussels and round gobies that hitchhike in the ballast water of cargo ships, or are introduced unintentionally. Often the invasives damage the native fish, plants, and ecosystems of the Great Lakes. Nothing has been done to effectively stop importing the invasives, and some have gone so far as to suggest that the St. Lawrence Seaway connecting the Great Lakes to the Atlantic Ocean should be closed. The IJC’s Dennis Schornack says he’s hopeful that we’ll soon see laws that will do more to help prevent invasive species from getting into the Lakes.
“In the United States, at least, there is pending legislation that has been pending for over two years now called the National Aquatic Invasive Species Act. This legislation is overdue. It’s time for Congress to act on it. And in the ’05 legislative Congressional year, it’s time for them to act. And that’s the place where the standards get set, the authority gets established and where all of the rubber really hits the road. Now, that’s just in the United States. Bi-nationally, because the Great Lakes are a shared resource, the IJC, that I’m the chair of the U.S. section, has continued to advocate cooperation and collaboration between the two countries in terms of at least setting a common standard, a common rule, common regulation on the Great Lakes. Because, obviously, setting it on one side of the boundary line doesn’t do any good if the other side doesn’t follow.”
Another issue that’s recieved a lot of attention in the Great Lakes region recently is water diversion. A document called Annex 2001 tackles the issue of how much water can be used or withdrawn from the Lakes. The various state governors and province premiers put together draft agreements for public comment. Schornack says there’s been a huge response, and a lot of it hasn’t been positive.
“They recieved, I think, over ten-thousand public comments. And there is differing viewpoint, a growing difference between the view taken in Canada and the view taken in the United States on this effort. Canada, the province of Ontario, has come out and point-blank opposed the existing documents. There are concerns in Canada that this is just some kind of a ruse to somehow allow diversions of the Great Lakes waters to occur. I’m not part of that viewpoint, to tell you the truth. What’s being done right now and what will happen in 2005 is that the comments are being digested, we’ll see new draft documents come out from the governors and premiers and hopefully begin the process making those agreements stick.”
Schornack says 2005 will also see some important reports on the economic costs of invasive species. Studies on the logistics of shipping, cargo ship traffic and alternative freight haulers and design plans that look at the total cost of shipping – including the infrastructure costs and the environmental damage caused by invasive species. It should be an interesting year for the Great Lake if Congress moves on key issues, and then finds money to make the Great Lakes more sound.
For the Great Lakes Radio Consortium, this is Lester Graham.
For decades, aquatic invaders have been plaguing the Great Lakes. They’ve changed the way the ecosystems work and affected the balance of life in the lakes. Most of them didn’t just wander in. They hitchhiked a ride into the Lakes in the ballast water of ships from across the Atlantic. The Great Lakes Radio Consortium’s Carolyn Gramling reports… now the combination of these invasive species is causing changes that concern scientists:
For decades, aquatic invaders have been plaguing the Great Lakes. They’ve changed the way the
ecosystems work and affected the balance of life in the lakes. Most of them didn’t just wander in.
They’ve hitchhiked a ride into the Lakes in the ballast water of ships from across the Atlantic. The
Great Lakes Radio Consortium’s Carolyn Gramling reports…now the combination of these invasive
species is causing changes that concern scientists:
Zebra mussels were one of those species that hitched a ride in the ballast of a ship. They first
appeared in the Lakes in the mid-1980s. Zebras and their cousins the quagga mussels compete for
food needed by aquatic animals native to the lakes.
Researchers say now these mussels are part of another problem. They’re changing the food web.
The food web is made up of organisms that feed on each other. Usually it’s a chain of small, even
microscopic species that are food for ever larger species. Zebra mussels are near the bottom. For
their food, they filter large volumes of water containing contaminant-laden algae and sediment. In
the process they ingest PCBs and other toxins.
Gene Kim is a researcher in the Ohio State University’s Aquatic Ecology Laboratory. He says that
zebra mussels and a non-native fish called the round goby have helped to form a new food chain
within Lake Erie – a chain that can connect harmful chemicals buried in lake mud to humans.
“A lot of the exotic species, these alien species, have incorporated themselves into the Lake Erie
food web, and there’s a lot of ramifications, in terms of, will they change the cycling of historical
contaminants that right now are in the sediments, but they could be redirected back into sport fish
and eventually, humans.”
Zebra mussels have few natural predators in North America, and they reproduce rapidly. As a
result, they’ve been wiping out native mussels and clogging up water intake pipes in the lake. So
the arrival of the round goby, which likes to eat zebra mussels, would seem to be good news.
Instead, it has proven to be a double-edged sword.
Roy Stein is a professor in Ohio State’s Aquatic Ecology Laboratory. He says the PCBs and other
contaminants, once held captive in the sediment at the bottom of Lake Erie are taken up by zebra
mussels, and then the zebras are eaten by the round goby.
“And then, interestingly enough, round gobies are important prey for smallmouth bass that people
eat, and all of a sudden we have the opportunity for those PCBs that were stored in the sediments
to come up through the food chain and influence humans.”
So, Stein says, those contaminants that were trapped in the sediment now have a pathway up the
Gene Kim’s research is confirming the link between smallmouth bass and round gobies. He says
it’s clear round gobies like to eat zebra mussels. But it’s less clear whether bass prefer to eat gobies
over other prey fish. So, Kim devised a laboratory behavior study that let the smallmouth bass
choose between several types of prey, including gobies, emerald shiners, and crayfish.
“The interesting thing is that they actually target these emerald shiners more often than round
gobies, but emerald shiners have superior escape abilities.”
Round gobies, Kim says, just don’t swim away as fast – and so get eaten the most. He adds that
when compared with the stomach contents of Lake Erie bass, this laboratory result is borne out –
more gobies were consumed than any other prey.
Roy Stein says that this puts the system in a kind of double jeopardy.
“The combination of PCBs plus being a slow prey causes perhaps more PCBs to move up through
the food web than otherwise might be the case.”
PCBs have been linked to cancer and birth defects in humans – and they’re not the only
contaminants in the lake.
Other research indicates this new food chain might be helping other pollutants in the sediment find
their way to humans. For example, another Ohio State study finds methylmercury is also getting
into the food web through invasive species. Methylmercury in fish can cause neurological problems
for expectant mothers and other health problems.
Doug Haffner is the Canada Research Chair for Great Lakes Environmental Health and a professor
of Biological Sciences at the University of Windsor. He agrees a zebra mussel – round goby –
smallmouth bass food chain has created a route that exposes humans to harmful chemicals in lake
“For a chemical to be of concern to us, it has to be biologically available, it has to be able to enter a
human being or a fish or whatever it might be. Some chemicals may be out there but not available;
we can measure them, but they’re not really a risk to the ecosystem per se. But processes can
change, which make them available.”
Martin Berg is a professor of Aquatic Ecology at Loyola University Chicago. He says the non-
native species have had a similar impact on PCB transfer from Lake Michigan sediment.
“You can think of it almost like a conduit, like a pipe. Now we have a direct link, as you move up
the food web, to organisms that are going to be directly consumed by humans.”
And the problem spreads as the non-native species expand their range. Researcher Gene Kim says
that the implications are far-reaching.
“Not only are we just talking about a Great Lakes phenomenon – zebra mussels have already
escaped into the Mississippi drainage, and right now round gobies – we’re spending a lot of money
to prevent round gobies from entering that same drainage.”
Scientists’ concerns about toxins in the Lakes are not limited to how invasive species are changing
the food web. Researchers say that other changes caused by people can help harmful chemicals
trapped in sediments to return to the ecosystem. Ultimately, they say, each of these issues is part
of a much larger concern: the overall health of the environment.
For the Great Lakes Radio Consortium, I’m Carolyn Gramling.
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:
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.