GLIN==> Illinois-Indiana Sea Grant News: Asian Carp May Compete with Key Mississippi River Fish

[Irene Miles <miles@uiuc.edu>]

June 28, 2004

Source: John Chick 
618-466-9690; chick@uiuc.edu

Asian Carp May Compete with Key Mississippi River
Fish 

URBANA--Invasive Asian carp consume similar food
as a native fish that is a major component of the Mississippi River
ecosystem, according to preliminary results of an Illinois-Indiana Sea
Grant study. If populations of Asian carp species go unchecked, they may
adversely affect numbers of gizzard shad, the most abundant fish in the
river.

Brought to the U.S. for use in aquaculture, Asian carp escaped into the
Mississippi River in the 1980s. They are now plentiful in much of the
river--in fact, they have moved into the Illinois River and are
approaching Lake Michigan. At this point, an experimental electric
barrier stands between these fish and the Great Lakes. But, concern is
high because Asian carp consume zooplankton, which all fishes typically
feed on in their larval stages, so they have the potential to adversely
affect many species of fish in the Mississippi River and Great Lakes.

John Chick and Mark Pegg, biologists at the Illinois Natural History
Survey, are assessing the potential impact of Asian carp on several
native Mississippi and Illinois River fish who feed in a similar fashion
to the carp, by filtering suspended food particles from the water current
through their gills.

By analyzing stomach contents, the researchers compared the diet of two
Asian carp species, bighead and silver carp, with the diet of paddlefish,
bigmouth buffalo and gizzard shad. “We sampled these fish in back-water
habitats during spring flooding, which is a good way to find all these
species in the same location,” said Chick. They also collected
zooplankton samples at the same site.

Despite the fact that Asian carp can grow to more than 50 pounds in the
Mississippi River, the researchers found that these species typically eat
zooplankton smaller than 200 microns in length, as do the prevalent
gizzard shad. “On the other hand, in our samples, paddlefish and bigmouth
buffalo primarily ate larger prey, including crustacean zooplankton,
insects and fish larvae,” explained Chick. 

“At this point there’s no evidence that Asian carp are reducing abundance
of zooplankton in the Mississippi River; it is a very productive system,”
said Chick. “But if populations of bighead and silver carp go unchecked,
zooplankton numbers may drop, impacting gizzard shad. The shad are eaten
by all predatory fish--channel catfish, blue catfish, flathead catfish,
largemouth bass, walleye and more.”

“If Asian carp populations are able to take off in Lake Michigan, the
impact will likely be even more detrimental,” said Chick. “The lake is a
less productive system, and its zooplankton populations have already been
depleted by zebra mussels.”

In addition to their preliminary data collection, the research team has
sampled fish from locations in the Mississippi and Illinois Rivers
throughout the spring and summer. When analyzed, this data will provide a
thorough picture of the diet of Asian carp and native filter-feeding fish
in these waterways.

Early detection of Asian carp in new waters can help control their
spread.You can help with the monitoring of these fish by learning how to
recognize them and reporting any sightings. To order a free Bighead and
Silver Carp Watch ID Card from Illinois-Indiana Sea Grant, visit
www.iisgcp.org/products/free.htm
on the Internet, or call Susan White at 217-333-9441 or email
white2@uiuc.edu.Report sightings in new locations online at
www.iisgcp.org/il-ans

or call 847-872-8677.

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The Illinois-Indiana Sea Grant College Program is one of more than 30 National Sea Grant College Programs. Created by Congress in 1966, Sea Grant combines university, government, business and industry expertise to address coastal and Great Lakes needs.  Funding is provided by the National Oceanic Atmospheric Administration (NOAA), U. S. Department of Commerce, the University of Illinois at Urbana-Champaign and Purdue University at West Lafayette, Indiana.

Irene Miles
Illinois-Indiana Sea Grant
376 NSRC
1101 W. Peabody Dr.
Urbana, Il 61801
(217) 333-8055
FAX (217) 333-8046