Carp Harvest Uses Innovative Techniques
A harvest of Asian carp in February from a recreational lake in St. Louis (Mo.) County that was two years in the planning used some innovative techniques that could provide another tool in the arsenal of those fighting the invasive species.
The harvest took three weeks and removed about 57,000 pounds of bighead, silver and grass carp from the lake, or about 90 percent of the estimated total. Small boats used engine noises and mild electric currents, to which the carp are sensitive, to herd them into pens made of fishing nets next to shore. The engine noise didn’t seem to bother other fish species.
According to Darrow Wenom—a commercial fisherman who took part and who has helped with previous carp-control efforts—when herded this way, the carp form into tight stacks or balls five or six fish deep, from which they are able to be hauled ashore and taken in backhoes to dumpsters.
“We used sound and shocking methods to herd the fish and then circle them with nets. This was an amazing breakthrough in understanding these fish. When they panic they school and form a tight pod for protection, which makes them easier to harvest.”
Wenom added, “I believe through everyone’s combined efforts and hard work, we now better understand how to deal with this invasive species in order to manage its population to protect our native fish in our lakes and waterways.
One of the largest natural lakes in Missouri, Creve Coeur Lake was formed from an oxbow cutoff of the Missouri River. It was a resort in the late 19th century, and ever since has been a popular site for sailing and recreational activities. The lake and surrounding 2,145 acres became the first St. Louis County park in 1945. Between 1974 and 1981, the lake was dredged from 18 inches to 10 feet deep and its surface area was increased from 220 to 320 acres. Since then, it has been regularly stocked with crappie by the Missouri Department of Conservation.
In 2009, floodwaters from the nearby Missouri River introduced the carp, the same population that has been there ever since. Since carp need running water to oxygenate their eggs, they could not reproduce. But the voracious algae-eaters began to displace other fish species nevertheless, and even to turn on each other. By the time of the removal, according to a park ranger who didn’t want to be named, they were “starving.”
Agencies involved in the harvest included the Missouri Department of Conservation, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey.
Several scientists involved in the effort told local media they planned to publish papers in scientific journals on the methods used.
University Receives 115-Pound Carp Specimen
Across the river from St. Louis, in Carbondale, Ill., Southern Illinois University-Carbondale announced February 13 that university researchers received what is believed to be the biggest specimen of black carp ever brought in for analysis.
The 115-pound female carp was caught by commercial fishermen in the Mississippi River near Cape Girardeau, Mo. SIU manages a program funded by the Illinois Department of Natural Resources that pays fisherman for black carp they turn over for research.
The zoology department in SIU’s College of Science will dissect and analyze the specimen to help study issues involving the carp’s range, feeding and breeding habits, and spread.