AUTHORS: Hannah Mulligan, Department of Natural Resource Management, South Dakota State University; Benjamin J. Schall, South Dakota Department of Game, Fish and Parks; Tanner Davis, South Dakota Department of Game, Fish and Parks; Greg W. Whitledge, Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University-Carbondale; Alison Coulter, Department of Natural Resource Management, South Dakota State University
ABSTRACT: Preventative management strategies are essential for minimizing the negative ecological, economic, and social impacts of invasive species. Silver Carp and Bighead Carp, two invasive species of concern in the United States, are currently managed using various containment and removal strategies to prevent further range expansion. Understanding where Silver Carp and Bighead Carp are recruiting and moving can assist managers in selecting removal locations to reduce recruitment and spread. The objectives of this project are to evaluate the natal origins of Silver Carp and Bighead Carp using otolith microchemistry to 1) determine recruitment sources and 2) identify movement among tributaries and main channel reaches throughout the Missouri River Basin. A maximum of 80 adult Silver Carp and Bighead Carp will be collected from each location (n = 22) in collaboration with state partners. Lapilli otoliths will be removed and processed for trace element analysis (barium, Ba; strontium, Sr; and calcium, Ca) and potentially δ18O analysis. Water samples will also be analyzed for trace elements (Ba, Sr, and Ca) and oxygen isotope ratios (δ18O). To determine natal origin, trace-elemental markers and their ratios (Sr:Ca, Ba:Ca) measured from otoliths will be compared to chemical signatures from the water samples. Correlation analysis will be used to evaluate relationships between element concentrations in water samples and otoliths. Trace elements and δ18O in lapilli otoliths that are correlated to water concentrations will be included in a model-based discriminant function or cluster analysis, such as k-nearest neighbor. Chemical composition results will be used to quantify the amount of movement based on the natal origins of adults. Results will complement ongoing telemetry work and spawning assessments, inform source-sink dynamics, and identify locations for targeted management actions such as removal.
