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Invasive Carp Threaten Native Species, Boaters
by Gordon Murdock

excerpted from Imprint, Summer 2004

In 1831, common carp were imported into North America. Less than two centuries later, they make up most of the biomass of fish in the Mississippi River. They uproot aquatic plants important to other fish and waterfowl and stir up sediments, releasing nutrients and other pollutants trapped there. Today, new invaders threaten further ecological disruption.

Bighead, silver, grass and black carp have been imported into the United States from Asia since 1960. All are native to rivers in China with conditions similar to those of the upper Mississippi. They would do well here. Possession in Minnesota is illegal.

Bighead and silver carp threaten Minnesota but are rare here (one bighead was found in Lake Pepin in 2003). Both are very common in the Iowa and Illinois waters of the MIssissippi and have moved upstream about 40 miles per year. Near St. Louis, the Asian carp population has increased 100 times (10,000 percent) from 1991 to 1993, when a backwater fish kill showed 97 percent of the fish to be Asian carp. The Asian carp population increased 600 times (60,000 percent) in the lower Illinois River from 1999 to 2000. Because a large female bighead or silver carp can lay up to one million eggs in a year, just a few fish could have a large effect.

Bighead and silver carp are filter feeders, straining tiny animals and plants (plankton) out of the water. Some may eat their weight in plankton daily. In eating plankton, these fish compete with native filter feeders such as paddlefish, bigmouth buffalo (a major commercial species), gizzard shad, and the various native mussel species, some threatened or endangered.

Silver carp have made the news because they may leap high out of the water when disturbed by watercraft. Boaters have been injured when speeding watercraft struck leaping fish. Hitting a 10-pound carp at 30 miles per hour is roughly like being hit with a 10-pound bag of flour dropped from the top of a three-story building. Silver carp can reach 110 pounds.

Grass and black carp are not now an issue in Minnesota. Grass carp are used in some places to clear out underwater weeds. But the threat of uncontrolled spread is great — and carp do not distinguish between desirable and undesirable plants. Black carp may not now be breeding anywhere in the U.S., but if they were to start, they would be a threat to our mussels and snails, which they eat.

Among the measures used to prevent the spread of invasive carp is an electric barrier being tested in Illinois. This technology conceivably could prevent Asian carp from entering Lake Michigan, but its effectiveness is not yet clear. Blocking migration with curtains of bubbles or using sounds to repel fish have been proposed but aren't proven. The Minnesota Department of Natural Resources is encouraging federal agencies and states to the south on the Mississippi to test these before fish reach our state.

At the University of Minnesota, fish geneticist Anne Kapuscinski, is studying how to assess risks of releasing sterile or genetically modified fish to reduce the numbers of Asian carp in the wild. Peter Sorensen is an expert on the responses of fish to sensory cues and especially how pheromones (chemical signals between individuals) might be used to control both common and Asian carp. Both are faculty in the Department of Fisheries, Wildlife and Conservation Biology in the University's College of Natural Resources.

Articles:

http://www.jsonline.com/news/state/may04/226545.asp
An article from a Wisconsin paper, Milwaukee Journal Sentinel, on Bighead carp and their threat to the great lakes eco system.

http://www.nwo.usace.army.mil/html/pde/RecRiver/EvalSamplingTechLifeHistoryBigheadCarpMissouriRiver.pdf
Information on bighead carp prepared by the Fish and Wildlife Service.

http://www.hq.usace.army.mil/cepa/pubs/may04/story9.htm
Article on invasive carp by a member of the Army Corp of Engineers St. Paul district.

http://www.glfc.org/fishmgmt/carp.asp
Summarizes options to slow the migration of Asian carp up the Mississippi.

http://www.scienceblog.com/community/older/2002/D/20024331.html
Summary of research behind electrical barriers against carp.

http://www.seagrant.wisc.edu/outreach/nis/Barrier/Barrier.html
Information on the electrical barrier before the Chicago Sanitary and Ship Canal.

http://www.startribune.com/stories/122/4825194.html
An article with basic information on the sterilization of black carp.

Research/Data:

http://www.umesc.usgs.gov/reports_publications/psrs/psr_2000_05.html
Summary of USGS data on invasive carp.

http://www.umesc.usgs.gov/data_library/fisheries/graphical/fish_front.html
Database of USGS data on different fish species. Interactive, search for charts and data on particular species populations in different areas.

http://nas.er.usgs.gov/fishes/index.html
USGS provides access to databases, distribution maps, and species lists and warnings about non-indigenous fish species.

http://www.dnr.state.mn.us/invasives/aquaticanimals/asiancarp/index.html
Provides access to the entire feasibility study on preventing Asian carp from spreading, as well as an article about the threat to Minnesota from Asian carp.

Other:

http://www.umesc.usgs.gov/invasive_species/asian_carp.html
USGS fast facts on Asian carp

http://www.optimizethroughdesign.com/testpage.htm
Short video on Asian carp in the Mississippi and efforts to prevent the fish migrating into the Great Lakes.

http://www.pierwisconsin.org/educ/LessonPDFs/AsianCarpInvasion.pdf
Lesson plan on Asian Carp.

http://wwwaux.cerc.cr.usgs.gov/MICRA/
Access to articles and power point presentations dealing with Asian Carp throughout the Mississippi.