Juvenile and subadult Gulf Sturgeon (Acipenser desotoi) use of the Pascagoula River estuary

Gulf Sturgeon (GS) are an anadromous species currently listed as “Threatened” under the Endangered Species Act. They reside in habitats across the northern Gulf of Mexico including coastal rivers, estuaries, and marine waters, making annual migrations between freshwater and marine habitats for spawning/summer resting and feeding, respectively. Since past studies prioritize adult movement, understanding how and when juvenile and subadult GS use the Pascagoula River estuary (PRE), a complex, bifurcated river delta federally designated as critical habitat is necessary to improve conservation efforts. My thesis assessed juvenile and subadult GS use of the PRE across four years (2020-2024) by analyzing transient and resident movement patterns, comparing the influence of environmental variables (conductivity, water temperature, gauge height, air pressure, tidal amplitude, rainfall), and calculating survival estimates of GS within the lower reaches of each distributary. Additionally, my thesis is the first to quantify depth and bottom features for defined sections of the PRE to associate with juvenile and subadult GS use within the system. I found GS used the western distributary more than the eastern, moved in/out of the PRE in response to all environmental variables, and showed lower survival probability in the west for acoustic tags with higher battery life. Younger juveniles spent more time within western sections predominated by sand when compared to subadults, and subadults had more variable use across each section. This thesis provides insight into juvenile and subadult GS movement and use within a natural and altered estuarine environment to help inform management and recovery goals.