Researchers Fight to Keep Asian Carp Out of WV’s Upper Ohio
Charleston Gazette Mail
22 July 2017
John McCoy , Staff Writer
There’s a war going on.
Along West Virginia’s western border, biologists are battling to
keep Asian carp from invading the Ohio River.
They might win. Then again, they might not. The work they’re doing
right now could decide which way the war will end.
The invaders already have infiltrated the river. Katie Zipfel, a
research biologist for the state Division of Natural Resources,
said individual fish have been detected as far north as Wheeling.
“That’s farther north than most people thought they’d ever go,”
she explained. “The good news is that there are aren’t many of
them in our part of the river.”
That isn’t the case farther downstream, where the river borders
Illinois and Indiana. There, the two Asian species — bighead carp
and silver carp — are so abundant they’re changing the river’s
Zipfel and her DNR colleagues don’t want that to happen to the 256
miles of the Ohio that border the Mountain State. That’s why West
Virginia has joined a coalition of federal and state agencies
trying to figure out what makes the invaders tick.
“We’re putting forth as much effort as we can to try to slow the
upriver expansion of these species,” Zipfel said.
The work they’re doing extends along several fronts. They have an
ongoing monitoring effort, which includes capturing fish, tracking
them, and searching for genetic clues that reveal their presence.
They also have a removal effort, which centers on capturing and
killing the carp.
“For part of the monitoring project, we sample the river as far
north as the Robert C. Byrd pool with gillnets or by
electrofishing,” Zipfel said. “The problem with sampling like that
is that Asian carp are notorious for being very hard to catch
unless they’re present in extraordinarily high densities. This
spring, for example, we only caught one bighead carp.”
The sampling efforts aren’t a waste of time, however, because they
allow Zipfel and her fellow biologists to keep tabs on how other
fish species are doing.
“We’re collecting [data on other fish] to be able to show any
impacts that might occur in the future if the invasion front does
advance [that far upriver],” she explained.
Telemetry studies make up the second part of the Asian carp team’s
monitoring effort. Biologists implant acoustic transmitters in the
abdomens of a few captured carp.
Receivers placed strategically along the river detect the signals
and record on a memory chip the identity of any transmitter-tagged
fish that passes nearby. The receiver array runs all the way
upriver to the Willow Island Dam near St. Marys.
Zipfel said telemetry data have shown that Asian carp can move
astonishing distances, and can do so quite quickly.
“One bighead carp that was tagged several pools downstream [in
Kentucky] moved several hundred miles in just a few days,” she
added. “It skipped by all the receivers in the Robert C. Byrd pool
and ended up in the lower Racine pool. We got pings on it from
receivers in the Ravenswood area. It’s still there.”
So far, only four tagged fish are known to be present in the river
— the one in the Racine pool, and three others tagged by a U.S.
Fish and Wildlife Service crew in Raccoon Creek, a tributary on
the river’s Ohio side. Zipfel said acoustic receivers are
gathering data on all four fishes’ movements.
Biologists also are gathering what they call environmental DNA,
“eDNA” for short. Essentially, they take water samples and analyze
them for any hint of bighead carp or silver carp DNA. Using that
approach, they have a chance to detect the presence of invaders
even in places where no carp have been captured or tagged.
The final arrow in the biologists’ quiver is an ongoing removal
effort, in which crews capture and kill all the carp they catch.
“We focus on areas where we know we have caught fish or where
people have been seeing fish,” Zipfel explained. “We set our
gillnets and get our electrofishing boats out there. The idea is
to make a lot of noise and herd the carp into the gillnets.
“We tried to do one of those last year, in the old lock chambers
just above the Robert C. Byrd Dam. We had crews from the West
Virginia DNR, from Kentucky and from the Fish and Wildlife
Service. It was a two-day effort, and we only caught four
bigheads. The Fish and Wildlife Service crew tagged three and let
them go, mainly because they thought they needed the [acoustic]
data. Those will be the only fish we release on our section of
river. Any other Asian carp we catch in the Robert C. Byrd pool
are as good as dead.”
One factor that might help keep the invaders out of the upper Ohio
is the nature of the river itself. Asian carp prefer muddy,
slow-moving rivers with lots of backwaters. The upper Ohio is
relatively clear, relatively fast-moving and doesn’t have many
backwaters. Zipfel warned, however, that Asian carp have a way of
proving wrong science’s conventional wisdom.
“Just when we think they won’t like a certain type of habitat,
they move in on us,” she said. “They’ve already gone places we
didn’t think they’d be. Competition [with other Asian carp] seems
to force them to move into non-preferred habitat.”
Scientists believe the upper Ohio’s relatively short pools might
impair the invaders’ ability to spawn, but that isn’t a sure
“Asian carp eggs need to stay suspended in the water for 24 to 36
hours in order to remain viable. That’s why spawning tends to take
place when the water is really high,” Zipfel explained. “Based on
high-water flows, a pool would have to be at least [62 miles] long
to keep the eggs suspended that many hours. All of our pools on
the Ohio are less than 62 miles long.
“However, recent studies show that in the right conditions, the
eggs could survive in as little as 15 miles. Given the overall
habitat, though, we think that even if adult carp ended up in [the
upper Ohio], they wouldn’t have much success spawning.”
Ultimately, the key to keeping Asian carp out of rivers might be
to find something that makes them uncomfortable.
“We think sound might be one way,” Zipfel said. “Maybe blast a
certain kind of noise to keep them away. We’d have to be careful,
though, to find a noise that didn’t affect paddlefish or blue
catfish, which are species that share the same habitat.”
The answer might ultimately come, oddly enough, from fishermen.
While Asian carp feed on plankton and are only caught by accident
on hook and line, efforts are underway to create a commercial
market for them.
“Commercial fishermen can catch Asian carp better than we can,”
Zipfel said. “Kentucky is setting up fish-processing plants for
them so they can sell the carp they catch for fertilizer and dog
food. Developing a market for Asian carp might ultimately be the
solution to the problem.”
Reach John McCoy at firstname.lastname@example.org, 304-348-1231 or
follow @GazMailOutdoors on Twitter.