National Geographic News
Photo of a man holding a small carp and a large carp.

These invasive silver and bighead carp were collected on the Illinois River in May 2011.

Photograph by Jon Amberg, U.S. Geological Survey

Brian Clark Howard

National Geographic

Published March 11, 2014

One of the most reviled invasive fish in North America has been unexpectedly found in the upper Mississippi River, raising concern about its spread, federal scientists announced Tuesday.

The invasive Asian carp has been breeding and spreading across the U.S. for more than 20 years, "but we were surprised that they got up so far," says Cindy Kolar, a science adviser on invasive species for the U.S. Geological Survey (USGS).

On Tuesday, USGS said its scientists found Asian carp eggs, including late-stage embryos nearly ready to hatch, in samples taken in 2013 from the upper Mississippi River in Lynxville, Wisconsin. That's 250 river miles (400 kilometers) upstream of their previously known reproductive populations.

Ecologists worry about the Asian carp because it is a large fish that can grow up to 110 pounds (50 kilograms), too big for predators to keep in check. It eats copious amounts of plankton and aquatic vegetation, with significant impacts on other species. Sports fishers fear it will crowd out their quarry.

As a result, the federal and state governments have spent hundreds of millions of dollars on efforts to thwart the spread of Asian carp, including the use of electric barriers, water guns, and scent-based lures to try to catch them.

Despite those efforts, the spread of the fish through the Mississippi River Basin has been well documented, with fishers occasionally pulling adult carp out of the water as far north as the Twin Cities, said Kolar. "But no one thought they would be reproducing that far north," she said of Lynxville, which is about 200 miles (320 kilometers) southeast of the Twin Cities.

Northern Exposure

Kolar says the scientists had not been looking for Asian carp around Lynxville. Instead, they were hoping "to get some background on other fish before Asian carp began invading."

But they found Asian carp eggs at seven locations between Keokuk, Iowa, and the main channel of the upper Mississippi River near Lynxville.

Kolar adds that the scientists are puzzled as to how the fish get so far up the Mississippi. At no time of the year is the water high enough for the fish to jump over a series of dams, she says.

"Were they carried inadvertently in bait buckets?" she asks. "Understanding how they got there is important in stopping their spread in the future."

juvenile bighead carp
Juvenile bighead carp are shown in a stock photo.
Photograph by U.S. Geological Survey

What Are Asian Carp?

The term Asian carp can be confusing, because it is generally applied to a group of related species, including the bighead (Hypophthalmichthys nobilis), silver (Hypophthalmichthys molitrix), grass (Ctenopharyngodon idella), and black carp (Mylopharyngodon piceus). These fish are all related to the familiar goldfish, koi, and common carp (Cyprinus carpio). The latter has already been established as an invasive species across most of North America for more than a century.

The eggs identified by the scientists today in the Mississippi were identified as either bighead or silver carp. The researchers say it's also possible that some may be grass carp.

Asian carp have worked their way northward through the Mississippi over the past few decades. They are thought to have escaped from aquaculture operations in the South in the 1970s, where they were imported to clean ponds.

Asian carp are generally considered better eating than common carp, and they are prized as food in Asia, where they have been farmed for more than 1,000 years. As part of efforts to control their spread in the U.S., a growing number of biologists are trying to convince people to catch and eat them, with varying degrees of success.

Are the Great Lakes Safe?

The biggest fears over the spread of the Asian carp have centered around whether they will make it into the Great Lakes, which are critically important for fishing and tourism, and are thought to be at high ecological risk. Millions of dollars have been spent on barriers in the Chicago River to try to keep them out, although critics have questioned if the invasion is just a matter of time.

In 2012, four grass carp were caught by a commercial fisher in the Sandusky River, a tributary of the Great Lakes.

Kolar says the finding in Lynxville doesn't have any direct bearing on whether the fish might enter the Great Lakes. She said the area is close enough to the headwaters of the river that it is essentially a "dead end."

But she says fears about the Asian carp's spread are "warranted." Kolar says, "We notice changes in fish populations in places where they are, so there is definitely concern about them getting into the Great Lakes."

12 comments
Holly Melley
Holly Melley

How about no limit fishing on them, freeze 'em and ship 'em back to China. After all they consider them a delicacy and lets face it the trade imbalance could use some shaking up.

Elliot Stephens
Elliot Stephens

We can put people to work, feed the hungry, and get rid of the carp as follows:  Hire twenty thousand fishermen, supply them with inflatable boats, and pay them each a living wage and benefits, and fire anyone who fails to catch carp.  The whole operation would cost less than one billion of Federal tax dollars per year, (based on $40,000 per worker per year including benefits, plus equipment.)  The US Gov't can't find 9 trillion dollars, or at least, cannot account for that much of the Pentagon's expenditures, so a billion shouldn't make a difference in the greater scheme of things.  Then, we sell the carp, or donate it to local food pantries.  

Carter Fox Jr.
Carter Fox Jr.

You want to get rid of the "Asian Carp", just figure out a way to cook them and they will be hunted for the dogfish they are!

JACQUE CARLE
JACQUE CARLE

I  think they are being released by people on purpose. Cheaper to grow here than have shipped here. It would not be the first fish that has been done with.

Dwayne LaGrou
Dwayne LaGrou

These fish need to be kept out of the Great Lakes. AT ALL COST!!! The potential damage to the Great Lakes ecosystem would be Devastating. These fry eat all of the vegetation that the local fish population rely on for cover from predators. And the Zebra Mussel has already been proven to cost the tax payers MILLIONS to be removed from fresh water intakes for industries that use the water for production. Not to mention, How would you feel about a Nuclear Reactor that uses water from the Lakes for cooling. We all know what happens if they cannot get water to flow fast enough through the cooling towers. The river between Chicago should be blocked in such a way to be CERTAIN that they cannot get through even in case of a flood. After all, That's how they got loose in the first place!!!

Food For Thought!

Louis Meluso
Louis Meluso

As I wrote to the N.G. editors months ago, here is as potential fish meal industry just ripe for the harvesting. Desiccated fish meal is a great organic plant fertilizer.  The business would use local labor, can't be out-sourced and has slight start-up costs. Though, fish plants are smelly, I hear.

KENNETH LANE
KENNETH LANE

Seems to me they are a boon to the rivers.  Cleaning up the over production of algae due to fertilizer run off seems good to me.  A better problem to solve is the insane erosion we enjoy in the hapless US.  Let's make the Mississippi less MUDDY!

Christopher Bove
Christopher Bove

They are not a problem in the Mississippi river ,the catfish just get bigger ,just like the zebra mussel was not,the fish eat them too,In fact they are good for the river they go where no other fish want to be and are food for the other fish,best blue cat bait is cut Chinese carp,so whats that tell you,they are eating them,biggest blue cats are coming out of the river than I ever seen.In my thirty years on the river .big hoax hundreds of millions of dollars for nothing.

Walter Matera
Walter Matera

The Chinese will buy them.  Keep catching and exporting . . . and not 'sustainably'!

Christopher Bove
Christopher Bove

@Dwayne LaGrou  The fish eat zebra mussels , predatory fish eat asian carp,we have both here on the mississippi ,commercial fishing is better then ever.I know what I'm talking about.I have lived fished and talked to all the fisherman on this river for thirty years. none of what you say has panned out.Big hoax

Dwayne LaGrou
Dwayne LaGrou

That may be true in the Mississippi floodplain, However the Ze bra mussels have cost the state of Michigan MILLIONS of dollars and have to be constantly removed from water intakes because they block the flow so much. PLUS, once these invasive fish reach a certain size they become an apex species with very few fish able to prey on them. The article even said they can reach sizes up to 100 pounds. There are very few Great Lakes fish that can survive a fish of that size. And then what about the juvenile fish and their loss of habitat? These fish would simply devastate the entire ecosystem of the Great Lakes. It is already suffering from so many smaller invasive species like the Zebra Mussel, the Goby and more than one invasive plant species. These fish are the WORST POSSIBLE Scenerio, and there is scientific proof of it already.

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