AUTHORS: Adam McDaniel ¹, Thomas Boersig III ¹, Jessica Howell ², Jason Goeckler ², Jahn Kallis ², Pablo Oleiro², Kellie Hanser ², Bryon Rochon ², Edward Sterling ², & Kasey Whiteman ¹ ¹ Missouri Department of Conservation; ² U.S. Fish & Wildlife Service
ABSTRACT: Invasive carp, particularly Silver Carp Hypopthalmichthys molitrix and Bighead Carp Hypopthalmichthys nobilis have expanded throughout the Mississippi River basin over the last thirty years. Studies to better understand these species and infer control measures in the Missouri River sub-basin have increased in the past several years. The Missouri Department of Conservation in collaboration with the U.S. Fish & Wildlife Service conducted intensive carp removals on two lower Missouri River tributaries with varying watersheds, the Grand River in northwest Missouri and Lamine River in central Missouri. This study evaluates the removal of invasive carp in closed and open fluvial systems, removal gears and effort to reach exploitation goals, changes in density of Silver Carp and immigration rates. Fish capture gears included experimental equipment such as the electrified paupier and dozer trawls in conjunction with standard electrofishing boats, and experimental gill nets to sample multiple habitat types. Hydroacoustic sonar surveys were conducted pre- and post-removal to quantify changes of invasive carp densities. Acoustic telemetry was also utilized to track daily movements and behavior of local Silver Carp previously implanted with acoustic tags. Removal efforts on the Grand River removed 28,848 kg of invasive carp and 17,506 Silver Carp in thirteen days of effort. Hydroacoustic density estimates indicated Silver Carp densities overall in 2023 were lower than 2022 and densities decreased each removal period in the Grand River. Missouri River tributaries most likely support all stages of invasive carp such as spawning, nursery and recruitment. Tributaries also represent areas invasive carp are probably vulnerable to overfishing as Silver Carp tend to congregate in deep slow pools and habitats easier to sample than mainstem Missouri River with faster water velocities and rock training structures. These efforts can aid biologists moving forward on future control and management actions of invasive carp in Missouri River tributaries.
