AUTHORS: Brett Anderson, Nebraska Cooperative Fish and Wildlife Research Unit, University of Nebraska-Lincoln; Jonathan J. Spurgeon, U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit, University of Nebraska-Lincoln.
ABSTRACT: Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (hereafter bigheaded carp) have invaded tributaries to the Missouri River and Platte River in Nebraska. Herding is a method used to increase the capture efficiency and detection probability of adult bigheaded carp by using active and passive sampling gears simultaneously. Nevertheless, more information is needed about how herding can be applied to mid-order rivers and how it compares to more conventional methods such as electrofishing. During June-July 2023, four herding techniques were assessed regarding their ability to elicit directional movement past an enclosure gate. Herding using an underwater speaker and pulsed-DC electrofishing proved effective at directing bigheaded carp into a capture area. From June-August 2024, herding was conducted on three tributaries to the Missouri River and one tributary to the Platte River to assess the effectiveness of gill-net sets at removing fish from a capture area. Herding and standard electrofishing were assessed based on catch rates, labor hours, and crew sizes. The results of this study will provide managers, researchers, and stakeholders knowledge regarding efficient and cost-effective sampling strategies for invasive bigheaded carp that enable assessments of presence and population status as well as provides control options for population reduction and potential removal.
