In a recent fishing exercise at Creve Coeur Lake in Maryland Heights, Missouri, our biologists worked with the Missouri Department of Conservation, U.S. Geological Survey, and the St. Louis County Parks Department to remove 47,000 Asian carp from the lake. The lake is primary infested with silver carp, a type of Asian carp that jumps out of the water when agitated by the sound of a boat motor. With conventional fishing methods unable to efficiently and effectively capture thousands of these unwanted fish, the team of partners looked to China, the country of origin for silver carp and other Asian carp species, for inspiration.
Able to swim 30 miles per hour, evade nets and fishing boats, as well as fishing hooks and lures, silver carp pose an extreme fishing challenge. While silver carp populations have steadily increased in lakes and rivers of the United States, they continue to decline in China where they are seen as a valuable source of nutrition. To remove thousands of Asian carp from the 320 acre Creve Coeur Lake, partners deployed a Chinese “fish herding” technique to slowly move fish across the lake into a confined space for removal.
Herding was done with high intensity sound coupled with deep water electricity and floating nets. The technique was largely successful, until the fish formed a tight ball, refusing to move the last few feet into the desired removal location. Concerned the tight ball of fish would escape, the quick-thinking partners assembled equipment and personnel to remove the fish from the water.
The successful removal of 47,000 silver carp, averaging 5 pounds each, was a monumental undertaking. From start to finish, the effort took three full weeks, 20 people, one track hoe, two skid loaders, 10 boats, and a mile of net. Cool temperatures at night also created ice on the lake that had to be broken each morning before work could continue.
Creve Coeur Park Lake, once packed full of silver carp, is now largely free from them. After nearly a decade of competing with native fish species for food and space, native sport fish like crappie have a chance to regain their foothold in the lake and create a desirable fishery for anglers. Once again, recreational boaters will be able to enjoy the lake without the excessive risk of jumping silver carp. The absence of the invasive Asian carp will also reduce the likelihood of smelly and unsightly fish kills at the scenic urban park. Through this partnership effort, it is anticipated the lessons learned will allow for other groups to successfully remove Asian carp in invaded waters throughout the Midwest.