Spatially Explicit Hydrological Influences on Individual Variation in Shovelnose Sturgeon Reproduction and Recruitment in a Regulated River

Flow regime and channel morphology of regulated streams and rivers determine habitat availability and in turn may influence reproductive and recruitment success of sturgeon populations. A mechanistic understanding of how hydrology drives sturgeon spawning behavior and larval dispersal is, however, still elusive. To understand how altered hydrologic conditions affect spatial and temporal population dynamics and viability, we developed a spatially explicit individual-based model (SEIBM) for shovelnose sturgeon (Scaphirhynchus  platorynchus) in the Lower Platte River (LPR), a tributary of the Missouri River. We simulated daily foraging, growth, survival, longitudinal movement, and spawning by tracking individual sturgeon's state variables using LPR hydrology and water quality data, including water discharge, temperature, dissolved oxygen, and turbidity. Preliminary simulation experiments indicated that changes in water discharge are highly correlated with sturgeon’s longitudinal movement and energy allocation including gonadal development in adults. Resulting changes in hydrologic experiences and altered energetics of sturgeon led to reduced growth and survival, and delayed maturation and spawning. Process-oriented models such as SEIBM can facilitate understanding of ecological consequences of altered hydrologic conditions and inform management decisions for sturgeon populations in large, regulated rivers.