Invasive Fish Rears Ugly Head in Great Lakes

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

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

Transcript

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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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

Related Links

Endangered Mussel Rides to Renewal

  • Biologists release bass, gills laced with Higgin's Eye Pearly Mussel larvae, into the Mississippi River. Photo courtesy of the Minnesota Department of Natural Resources.

Up and down the Mississippi River, people once collected tons of mussels for the pearl button industry. Factories stamped out pearl buttons from the shells, sometimes wiping out 50,000 tons of mussels annually in the early part of the last century. In recent years, the biggest threat to local mussel species has come from the zebra mussel. That invasive species came to North America in the ballast water of ships and has since disrupted many local ecosystems. Today, there’s a new effort underway to bring back local species like the Higgin’s Eye Pearly Mussel, and it’s in an unlikely place. The Great Lakes Radio Consortium’s Todd Melby has this report:

Transcript

Up and down the Mississippi River, people once collected tons of mussels for
the pearl button industry. Factories stamped out pearl buttons from the shells,
sometimes wiping out 50,000 tons of mussels annually in the early part of
the last century. In recent years, the biggest threat to local mussel species
has come from the zebra mussel. That invasive species came to North America in
the ballast water of ships and has since disrupted many local ecosystems. Today,
there’s a new effort underway to bring back local species like the Higgin’s
Eye Pearly Mussel. And it’s in an unlikely place. The Great Lakes Radio Consortium’s
Todd Melby has this report:


Urban areas like Minneapolis-Saint Paul might seem like an unusual
location to boost the population of an endangered species.


But it’s here, below a busy bridge that spans the Mississippi River, that
biologists are searching for a safe place for their project. Divers have
just come up from the bottom of the river with a few mussel specimens.


“Well, we’ve got Big Toe, Maple Leaf, Three Ridge. Good enough I think.”


That’s Mike Davis rattling off the names of mussel species. Davis is
a biologist with the Minnesota Department of Natural Resources. The fact that
some mussels live in this part of the river makes Davis think that this
might be a good spot for the Higgin’s Eye. The Higgin’s Eye, which has an olive-
colored shell, has been languishing on the Endangered Species List since
1976.


Just two decades ago, this part of the river suffered from sewage runoff. The river is cleaner now and some mussels have returned. But not the Higgin’s Eye. And that has Roger Gordon worried. He’s a biologist with the U.S. Fish and Wildlife Service.


“They function as the kidneys of the river, more or less. They siphon everything that
goes through the river. They are a very good indicator species if we have a problem in the environment. They are usually the first species to get hit hard and disappear.”


For the past decade or so, it’s been the zebra mussel that’s been hitting the Higgin’s Eye. But the zebra mussel hasn’t made it to this part of the river. That’s why biologists are on a small flotilla of boats on this morning with 800 large-mouth bass. The bass and the Higgin’s Eye have a strong connection. Attached to the gills of those bass are thousands of Higgin’s Eye larvae.


“Right now, we’re counting fish in the cage. We have a known number of fish, 25 in
this case, that we’re going to place in these cages. And hopefully over the next several weeks, they’ll drop off and we’ll have clams in the river.”


Melby: “You’re putting them in the bucket?”


“Right now we’re putting them in a bucket and placing them in the cage over the
side of the boat.”


(sound of buckets banging and water sloshing)


The bass are put in cages so they don’t swim somewhere that’s not a good home for the Higgin’s Eye. In the wild, adult females mussels shoot embryos at unsuspecting fish swimming overhead.


“The larvae have a chemo-receptor in them. When they touch flesh, they actually shut. It’s a one-shot deal. If that fish clamps on a fin or an eyeball or a lip, it’s a no-go. He’s not going to develop. But if he’s lucky, and he just happens to be going through a gill arch of a fish and it’s the right fish, the right species of fish and the right size fish, it
will shut on that gill.”


But the Higgin’s Eye population is too low to leave to chance.


(Bubbling sounds of fish hatchery)


So Gordon and his colleagues bumped up the number of mussel larvae
per fish here at a federal fish hatchery in Genoa, Wisconsin. Instead of just a
few larvae per fish, the bass dropped into the Mississippi have several dozen
larvae attached to their gills.


That prep work took place inside the “Clam Shack,” which is really
just a metal pole barn that biologists built themselves.


“We didn’t have any money to do this. We scraped up and saved up at the end
of the year. We had seven or eight-thousand dollars. The hatchery guys just got together and built this little building.”


Since beginning their work two years ago, they’ve added approximately
12,000 mussel-rich fish to rivers in Wisconsin, Illinois, Iowa and Minnesota.


“We’re probably going to have to build another little building
like this. But we’ll scrape along and do what we can.”


Back on the river, Mike Davis of the Minnesota DNR calls the return
of the Higgin’s Eye historic. But with the zebra mussel closing in on native
mussel species like the Higgin’s Eye, he’s also a bit wistful.


“The former dead zone of the Mississippi may become
one of the last refuges for the Mississippi’s mussel species.”


In September, divers return to that same spot to check on the Higgin’s
Eye. They hope to find thousands of young clams nestled safely in their new
home. For the Great Lakes Radio Consortium, I’m Todd Melby.