AUTHORS: Jenna Ruoss, School of Natural Resources - University of Nebraska-Lincoln; Christopher Pullano, School of Natural Resources - University of Nebraska-Lincoln; Mark Pegg, School of Natural Resources - University of Nebraska-Lincoln; Jonathan Spurgeon, U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit; Kirk Steffensen, Nebraska Game and Parks Commission
ABSTRACT: Pallid Sturgeon Scaphirhynchus albus is a long-lived species that occupy the lower Mississippi River and the mainstem Missouri River, along with its major tributaries. In 1990, Pallid Sturgeon was listed as federally endangered, stemming from anthropogenic activities including habitat alterations and overharvesting leading to population declines. Conservation efforts and studies have primarily focused on understanding life-history requirements, population dynamics, habitat use, and productivity in the mainstem Mississippi and Missouri rivers. Limited information exists on the potential role of tributaries for Pallid Sturgeon recovery. Previous studies documented that Pallid Sturgeon occupy the lower Platte River, a large tributary to the Missouri River, year-round. Nevertheless, the environmental cues that trigger movement into and out of the Platte River are not fully understood. Therefore, our objective was to assess potential environmental cues for immigration and emigration between the Platte and Missouri rivers using acoustic telemetry. We implanted 29 acoustic transmitters and recorded an additional 64 unique Pallid Sturgeon, previously tagged by other agencies in the mainstem Missouri River, throughout 2022-2023 in the Platte River. Pallid Sturgeon were assigned to one of three migratory statuses (e.g., immigration, emigration, or individual occurrence). We used generalized linear models to investigate the additive effects of mean discharge, mean temperature, and photoperiod for Pallid Sturgeon immigration and emigration at the Platte River confluence with the Missouri River. We determined that the global model with the additive effects of mean discharge, mean temperature, and photoperiod was the highest-ranking model for predicting the probability of immigration. In contrast, mean temperature was identified as the best candidate model for predicting the probability of emigration. Our findings provide important insights concerning Pallid Sturgeon migration between river systems. The high affinity that Pallid Sturgeon displayed for the Platte River could suggest that the tributary plays an important role in fulfilling their life-history.
