AUTHORS: William J. Radigan, University of Nebraska; Dr. Mark Pegg, University of Nebraska; Christopher Longhenry, South Dakota Department of Game, Fish, and Parks, Dr. Cameron Goble, Alberta Environment and Protected Areas; Dr. Kevin Pope, United States Geological Survey—Nebraska Cooperative Fish and Wildlife Research Unit
ABSTRACT: Walleye Sander vitreus and Sauger Sander canadensis are both socioeconomically important sportfish species in Lewis and Clark Lake, an interjurisdictionally managed mainstem Missouri River reservoir fishery. Adult Walleye (n=136) and adult Sauger (n=82) movement patterns were assessed from March 2021 to September 2024 among four management zones corresponding roughly to quarters of Lewis and Clark Lake using acoustic telemetry. We used a multistate live-dead model approach to assess survival, detection, and movement probabilities. Walleye survival probabilities (mean 85%) varied over time. Detection (mean 81%) and movement (mean 14%) probabilities varied by zone. Sauger detection probabilities varied by zone (mean 58%), and transition probabilities varied by sex, with female Sauger more likely (mean 14%) to transition among zones than male Sauger (mean 6%). Approximately 34-44% of all Walleye and Sauger were site residents, moving less than 10 km from their tagging location over the study duration. Non-site resident male and female Sauger utilized 44-47 km of the reservoir. Female Walleye utilized more of the reservoir (58 km) than male Walleye (45 km). Walleye tagged near Fort Randall Dam utilized more of the reservoir (69-72 km) than Walleye tagged elsewhere (47 km). Exploitation estimates were derived from angler-reported tags and entrainment estimates were based on detections recorded on receivers placed downstream of Gavins Point Dam. Annual exploitation (0-19%) and entrainment (0-5%) are considerable sources of loss for adult Walleye and adult Sauger in Lewis and Clark Lake. Examination of Walleye and Sauger movement patterns and sources of loss enables fisheries managers to focus management on areas identified to be important for spawning and validates the appropriateness of maintaining current harvest regulations.
