Asian carp pose formidable threat
to Midwest waters
By Dennis Lien
Knight Ridder Newspapers
BOONVILLE, Mo. - Fishing for catfish on the Missouri
River in July, Gary Hoskins, his daughter and son-in-law
found themselves in the middle of a spectacular show.
"Just as we started up the Lamine River, my daughter
said, "Look at all the lightning bugs,' " said
Hoskins, who lives in nearby Nelson, Mo. "She said,
"It looks like Christmas in July.' "
As Hoskins turned to his left, a 30-pound silver carp
shot out of the river and struck him on the right side
of his face, then fell to the boat floor. The blow knocked
a molar from his mouth and the fish's fin sliced his arm.
Downriver near Hartsburg, Vivian Nichols had a similar
encounter. She and her husband, Edwin, were circling their
boat through the quiet waters behind a wing dike, when
a silver carp leaped from the river and whacked her on
the nose, breaking it.
While her husband and a friend scrambled to corral the
fish, Vivian lay across a center console, blood streaming
from her nose.
"They didn't realize I had been hurt," she
said. "They were talking and saying, `I can't believe
this fish jumped into the boat.' I'm going, `Hey, guys!'
"I thought it was the fish's blood," Edwin
Life on the Missouri River has changed a lot recently,
thanks to the huge Asian carp that have invaded seemingly
every bay and inlet of the river's watershed. The fish
- the ugly bighead carp and the frenzied, leaping silver
carp - have made it all the way up the Missouri to South
Dakota and are threatening Minnesota via the Mississippi
Their potential impact in Minnesota, where sport fishing
is a $2.5 billion industry, could be enormous. With four
major river systems and almost 12,000 lakes, the state
has 750,000 registered boats, more per capita than anywhere
else in the United States. Only three states have more
On the Missouri and its tributaries, people now think
twice about taking a spin in their personal watercraft.
They avoid fishing by themselves at night. They watch
their speed as they head along the river. They've even
constructed barriers, or carp guards, on their boats,
all to avoid injury from silver carp, which become so
disturbed by engine noise that, without warning, they
leap 6 to 10 feet into the air, often landing in boats.
"I've had at least 50 of 'em land in my boat,"
"We thought it used to be funny," said Nichols,
a part-time commercial fisherman from Hartsburg. "But
it ain't funny anymore."
Imported from Asia in the early 1970s by Southern aquaculture
farmers to consume unwanted plant growth in ponds, silver
and bighead carp later escaped or were released into the
wild, where they have flourished, moving up major rivers
and tributaries over the past two decades.
Bighead carp can tip the scales at more than 100 pounds,
with silver carp typically a bit smaller. Voracious eaters,
they consume zooplankton and phytoplankton, tiny organisms
at the base of the aquatic food chain, more efficiently
than do native bigmouth buffalo and sturgeon. Other native
larval fish and mussels also need that plankton.
In addition, they produce huge quantities of eggs. "A
50-pounder we caught had a 5-gallon bucket of babies in
it," Edwin Nichols said.
Neither fish would win a beauty contest, but the bighead
is particularly ugly, with a disproportionately large
head and eyes set lower than the mouth, giving it an upside-down
appearance. Both bleed easily, leaving the insides of
boats a mess.
In the lee side of the Missouri's many wing dikes, where
they find protection from the swift current, they hang
out in large numbers.
"There's an awful lot of fish in there," Duane
Chapman, a fisheries biologist for the U.S. Geological
Survey in nearby Columbia, observed at one of those areas
on a recent outing to capture carp, gutting some for food
samples and tagging others to learn more about their movements.
After setting long nets to close escape routes, Chapman
whirled the boat around a confined area between the dike,
a sandbar and the shore to chase fish into nets. Most
passes produced at least one silver carp, leaping behind
or alongside the boat. With loud bangs, they also slammed
into the bottom of the hull. One landed in the boat.
In short order, the nets held almost three dozen fish,
almost all of them 10- to 30-pound bighead and silver
carp. Three buffalo and a shovelnose sturgeon were the
only native fish caught.
Chapman said it is difficult to measure the ecological
impact on the Missouri, the longest river in North America.
But he said the numbers and size of the carp pose problems.
"Their impact on the environment is directly proportional
to their biomass," Chapman said. "And under
the right kind of circumstances, they can reach enormous
biomasses. Sometimes, when you have invaders, there's
a huge peak, then it drops after a while. We haven't seen
a sign like that with Asian carp, but it's possible."
In St. Paul, Jay Rendall, head of the Minnesota Department
of Natural Resources' exotics species program, has been
warning about approaching Asian carp for years.
To get here, the fish have a straight shot north, interrupted
only by a penetrable system of locks and dams.
They already are moving up the Illinois River, threatening
the Great Lakes, with only an electrical barrier near
Chicago standing in their way. Last month, a 23-pound
bighead carp was netted in Lake Pepin, 100 miles farther
north than any previous discovery. Silver carp, which
apparently got into the wild later than bighead carp,
are believed to be still farther down the Mississippi.
Rendall and other state and federal fisheries specialists
in the Midwest are desperately trying to come up with
ways to hold the fish at bay. In the next few months,
they'll explore a variety of options, including electric
or acoustic barriers on the Mississippi and chemical ways
of tricking the fish.
If they get here, they could have a profound impact on
Minnesota's fishing and recreational industries, he said.
"Because they consume such a large amount of the
food chain, they could dramatically reduce what is available
for other species," Rendall said. "The other
big impact is on recreation. … The impact of silver carp
on water recreation could be dramatic. In the South, people
are starting to not be very excited about going on the
water when fish jump in their boats."
A national task force has been meeting to devise a federal
strategy and hopes to have a proposal ready by August.
The U.S. Fish and Wildlife Service, meanwhile, is entertaining
proposals to place bighead and silver carp on a national
list of injurious species, which would make it illegal
to import them or move them across state lines without
a permit, actions some have described as too little and
"If we could wave a wand and get them out of the
Mississippi, listing them might make sense," said
Mike Freeze, an Arkansas fish farmer and vice president
of the National Aquaculture Association, a trade organization
of 4,000 fish farms. "Without that, it just doesn't."
The agency also is considering similar actions against
black carp, another Asian native and a mollusk-eating
monster. Authorities do not believe any reproducing black
carp exist in the wild.
The aquaculture industry wants to keep the option of
moving sterile black carp across state lines and of shipping
live bighead carp to fish markets.
"The silver will be the least controversial of the
three," predicted Kari Duncan, a U.S. Fish and Wildlife
Service fisheries biologist.
What scientists like Chapman learn will play a crucial
role in the effort to minimize the impact of the fish.
Chapman has been trying to determine precisely what they
eat and how the diet changes during the year, whether
baby fish make up any portion of the diet, what types
of habitat the fish prefer, and their spawning patterns
and habitat needs.
Eventually, he said, scientists may be able to generate
chemical substances that carp use to transmit information,
disrupting their normal patterns. Already, he believes
bighead carp in Missouri move long distances up tributaries
during the winter while silver carp prefer to remain in
the river's main channel.
As a rule, the carp are tough to net, according to Chapman.
"They're so darned net-shy," he said. "They
know what nets are and they avoid them."
Spending as much time as he does on the Missouri, Chapman
also has observed how people have changed their behavior.
"We don't have the amount of recreation on the river
that you guys (in Minnesota) do," he said. "We
don't have as many impacts from Asian carp as you'd have.
But everybody knows they are out there, silver carp in
"Every boat you pass is doing something related
to jumping fish. Some have homemade spears, lawn chairs
they hide behind, or nets hanging out of the boat just
to catch them out of the air. Everybody you see driving
up the river is in some way dealing with these fish."
On many of the tributaries, people used to zip around
on personal watercraft. "You do not see that anymore,"
Chapman said. " If you use a tributary, you use them
In Missouri, the state encourages commercial and recreational
anglers to catch and keep all the Asian carp they want.
"Asian carp are by far the most abundant fish in
our part of the world," Chapman said.
Fishing, commercial and recreational, may not provide
the final answer, but it promises to cut down the numbers,
reducing the impact of the fish.
At the Big River Fish Corp., in Pearl, Ill., Rick Smith
said he wants all the Asian carp he can get. The company
processes and sells the fish, which, until recently, have
only appealed to ethnic Asian communities.
With each bout of publicity, however, Big River Fish
and other processors are finding new markets for the fish,
which Chapman and others describe as bony, but good and
flaky. Recently, for example, the company sold 200,000
pounds to a Spirit Lake, Iowa, company, which has since
put in another order.
Smith, Big River's owner, has only been able to offer
10 cents a pound for the carp, well below what commercial
fishermen need to make a decent living. But he said that
could improve as demand increases.
Meanwhile, he said, the government should consider subsidizing
commercial fishing, instead of spending millions of dollars
on other efforts. In China, the carp are overfished, according
to Chapman and Smith.
"If China can do it, we can do it," Smith said.
"We can take those fish out of the rivers, bring
the numbers down."
Without some sort of incentive, that won't happen, according
to Nichols, the Hartsburg fisherman.
He agreed that 10 cents a pound for carp is hardly worth
the effort. The fish, he said, tear up expensive trammel
nets, fish markets are too far away, and only about a
quarter of the fish is salvageable as meat.
"The meat is not bad, but the waste is so bad,"
He and folks like Mike Rea, a man from O'Fallon, Mo.,
who was struck in the chest and knocked in the river by
a silver carp while using a canoe to get to a hunting
spot, have some advice for Minnesota and Wisconsin residents.
"You won't want `em," said Nichols, who grew
up in the small Missouri River town. "They're filter
eaters. They eat everything. And that affects all the
other species. Nothing else has anything to eat. You'll
be sick of 'em."
"Somebody is going to probably die from being hit
by these things," Rea said. "I'm almost positive."