Empirical, spatially explicit natural mortality and movement rate estimates for the threatened Gulf sturgeon (Acipenser oxyrinchus desotoi)

Understanding mortality rates and movement patterns across a species' distribution can provide key insight necessary for developing effective conservation, recovery, and management plans. We directly estimated site fidelity and natural mortality rates for the threatened Gulf sturgeon (Acipenser oxyrinchus desotoi) across a large portion of their range in the northern Gulf of Mexico using acoustic telemetry methods and a simulation-tested, multistate mark-recapture model. Our results suggest that fidelity rates to riverine habitats used during spring and summer are high, but natural mortality rates vary widely. Our results are highly relevant for managing this species. The high fidelity rates, coupled with supporting genetic analyses, suggest that management of individual riverine populations of Gulf sturgeon should be considered. The need for individual river-based management is exacerbated by the variation in natural mortality rates among rivers. The reasons for these differences in mortality are unclear, but are an important area of future research because higher mortality rates may impede recovery of some Gulf sturgeon populations to stated management targets.