Current and Historic Status of Shortnose Sturgeon in the Altamaha River, Georgia

The shortnose sturgeon is a small long-lived species of fish that is currently protected by the United States Endangered Species Act. As part of the Endangered Species Act, a comprehensive species recovery plan must be constructed that includes an assessment of current status and a measurable recovery threshold. Presently, limited information is included in the current species recovery plan regarding the current and historic status of this species in southern systems. Such information represents a critical research need for successful conservation and restoration. Thus, the objective of this study was to assess the current status and to establish a recovery threshold for shortnose sturgeon in the Altamaha River, Georgia, using information gathered from a long-term population dynamics study. From 2004-2010 we sampled shortnose sturgeon in the Altamaha using anchored entanglement gear. For each year of the study, we used mark-recapture analysis to assess abundance, survival and recruitment of shortnose sturgeon. Our results suggested that reproductive success of shortnose sturgeon was positively correlated with spring river flow. To estimate historic abundance, we then constructed an age-structured population model that incorporated empirically derived demographic rates and historic river flows. Based on our model, the historic population of adult shortnose sturgeon in the Altamaha varied between 1400 and 4300 individuals. Our study demonstrates that long-term population assessment can be used to infer past abundance and current status when historical data is lacking. The results of this study can be used to establish an appropriate recovery goal and to inform conservation policy regarding shortnose sturgeon in the southeastern United States.