Non-natal Adult Atlantic Sturgeon Are Common in the Altamaha River Estuary, Georgia, USA

The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus is an anadromous species with a wide range along the Atlantic coast of North America. Because of overharvest and a variety of other anthropogenic stressors, the numbers of estuaries that currently host successful natural reproduction and the abundances of extant populations are depressed compared to historic numbers, resulting in its listing under the US Endangered Species Act as five Distinct Population Segments (DPS). Atlantic sturgeon are vulnerable to stressors not only within their natal estuaries but also at distant locales because of the highly migratory behavior of their subadult and adult life stages. In this study, we used our previously derived microsatellite DNA catalogue of 13 reference spawning populations and Individual-Based Assignment testing to determine the origin of 202 adult Atlantic sturgeon that were collected from the lower Altamaha River during spring, several months prior to their fall upriver spawning. We found that approximately one third (37%) of these adults assigned to populations other than the Altamaha, almost all (96%) to other populations within the South Atlantic DPS, a finding consistent with our earlier acoustic telemetry results. These results have management implications, including the likelihood of recolonization of depleted populations in the South Atlantic DPS and the compilation of reference population genetic profiles used in population delineation and mixed-stock analyses.