Project Sampling Efficiency Assessment for Silver Carp and Bighead Carp in Nebraska Mid-Order Streams and Rivers

Currently, eDNA is being used to investigate the distribution of invasive carp among lotic systems in Nebraska. However, attempts to verify eDNA results via live-fish collection have seen limited success due in part to limited understanding life-stage specific habitat use within prairie systems and the sampling methods to collect individuals effectively among different habitat types. Therefore, the study objectives of this project are to: (1) investigate sampling methods (i.e., towed trawls, various net configurations, and different electrofishing methods, etc.) that can effectively sample the invasive carp population, and (2) devise a sampling protocol for use in prairie systems that can target different life-stages of invasive carp populations. Such a protocol can be used to inform information gaps based on desired management objectives including documenting presence, assessing demographic rates, and/or eradication efforts. We have employed multiple gear-types including trawls, nets, and tow-barge electrofishing. Sampling efforts occured in the spring, summer, and fall of 2023 and 2024. We focused on sampling efforts in mid-order prairie streams and rivers that are tributaries to the Missouri River and the Platte River in Nebraska. Streams and systems may include the Blue River, Nemaha Rivers, and Papillion Creek, along the Missouri River. Streams and systems may include the Salt Creek, Elkhorn River, Shell Creek, and Loup River along the Platte River. We have used information from eDNA results to direct sampling to locations with both positive and negative results for presence of invasive carp. Lower reaches of these systems may be accessible by boats using traditional sampling gears. We sampled river and stream reaches higher in the watersheds where traditional methods are not easily employed.

Goals

Invasive Bighead Carp and Silver Carp are expanding into Great Plains rivers and limited information regarding basic population demographics exists. Information on population demographics including abundance and reproduction can highlight areas where populations are expanding and possibly contributing individuals to other aquatic systems.