Baker, M. A., E. C. Ingram, D. L. Higginbotham, B. J. Irwin, and A. G. Fox. 2023. Refining capture-recapture recruitment estimation methods for Atlantic Sturgeon. Endangered Species Research 51: 203-214. https://doi.org/10.3354/esr01250
Abstract
The Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) was once of great commercial importance in many coastal rivers of the eastern U.S.A. Over the 19th–20th centuries, most historical stocks of Atlantic Sturgeon were depleted by human activities. Estimating recruitment for the remaining populations is challenging due to sampling constraints, limited age data, and natural variability. However, recruitment estimates could inform recovery efforts. The objectives of this study were to compare two modeling approaches to estimate recruitment of age-1 Atlantic Sturgeon and provide an updated index of abundance across more than a decade of sampling in the Altamaha River, GA. First, we constructed capture histories of river-resident juveniles, using capture-mark-recapture data collected from 2008–2020, and assigned ages based on length-frequency analysis. Second, we compared more traditional Huggins closed population models and a recent nonlinear extension of Huggins models – vector generalized additive models (VGAMs) – to estimate abundance of age-1 fish. Both model types suggested similar yearly age-1 abundance estimates, which varied from 163 in 2017 to 3,839 in 2010, but the VGAMs provided more direct interpretation for factors that might affect capture probability (e.g., sampling effort, temperature, fish length). This study indicates that the Altamaha River Atlantic Sturgeon population has remained relatively stable over the past decade, and provides a long-term baseline which will better allow managers to assess the effects of either future restoration actions or environmental disturbances on the population.