Nebraskaland

January-February 2021 • Nebraskaland 47 fi sh moved the entire length of the lake in a matter of hours. "The distance that we're able to push these fi sh and the rapidity with which were able to do it is frankly amazing," Chapman said. "The great advantage we have with this method when it comes to bycatch is most of our native fi sh don't run away from the sound like the carp do." Using sound, electricity and block nets to drive the fi sh to a capture area, state and federal biologists and commercial fi shermen removed 100,000 pounds of silver and bighead carp. Similar eff orts have since been conducted on other lakes in Illinois, a section of the Illinois River, bays of Kentucky Lake, and several lakes in Missouri. At Creve Coeur Lake, a 2,100-acre lake in suburban St. Louis, biologists and commercial fi shermen spent three weeks in 2018 driving fi sh and setting nets and, in the end, removed about 47,000 silver and bighead carp, weighing 225,000 pounds. Many more fi sh were released from the trap nets when ice storms and scheduling confl icts ended the project. Not only had the Asian carp become a nuisance to kayakers and other users of Creve Couer, they also had decimated what was a premier crappie fi shery. Chapman suspected several years ago that crappies would be the game fi sh most aff ected by Asian carp, and that is coming to fruition. "In all of these fl oodplain lakes, when they get Asian carp in them, the crappie catch goes through the fl oor eventually," he said. The reason, he believes, is reduced recruitment because 2- to 4-inch crappie compete directly with large carp for that zooplankton resource. The year carp were removed, crappie recruitment was the best it had been since their arrival, and offi cials are now working on a barrier to keep the invasive fi sh out for good after the next roundup. The eff ects Asian carp can have on a fi shery were evident at Lake Yankton, located below Gavins Point Dam. When silver and bighead carp and other rough fi sh invaded the border water during fl ooding on the Missouri River in 2011, the game fi sh populations collapsed. By the time the lake was renovated in 2014, rough fi sh, primarily silver carp, made up 90 percent of the biomass. Bass, panfi sh, catfi sh and walleye, as well as aquatic vegetation, have since thrived. CONSIDERABLY smaller in size, the work at Hansen Lake No. 3 wouldn't require the manpower or equipment needed at other operations. The fi rst afternoon on the lake, Havranek, Riedmann and their crews used boats with side-scan sonar to survey the lake. A shallow bay on the east end of the lake where they planned to net the fi sh was devoid of them. A narrow channel connects this bay to the main lake where sonar found several large schools of Asian carp. Using boats equipped with underwater speakers, they drove fi sh out of the western portion of the lake and left speakers running overnight on the west shore. The next day, they again used sound to again push fi sh east before setting a block net across the middle of the lake. Gill nets were set on the ends of the net and behind a small hole beneath it in an area that was deeper than the net. They continued to use sound and an electrofi shing boat to drive fi sh east before leaving speakers running on the block net overnight. Tony Havranek of WSB Engineering in Minnesota deploys an underwater speaker used to drive Asian carp in Hanson Lake. F our species of carp — bighead, silver, grass and black — were brought to the United States in the 1960s and 1970s. All but black carp were brought in to control algae and vegetation in fish farms in Arkansas. The black carp, which feeds on snails and mussels, arrived in a shipment of grass carp stock. Asian carp escaped during flooding or accidental releases and have since spread throughout the Mississippi River and its tributaries, including the Missouri, Ohio and Illinois rivers. Silver carp, the most abundant and most annoying of the species due to their predication to jump as high as 10 feet out of the water when startled, especially by a passing boat, are believed to be present in at least 17 states. BIGHEAD SILVER GRASS BLACK

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