Recruitment of Juvenile Atlantic Sturgeon in the Savannah River, Georgia

Abstract

AbstractAtlantic Sturgeon Acipenser oxyrinchus oxyrinchus were once abundant along the Atlantic coast of North America from the Saint Lawrence River, Canada, to the St. Johns River, Florida. Severe overfishing, coupled with habitat losses during the 1900s, resulted in major population declines that eventually led to the subspecies’ listing under the U.S. Endangered Species Act in 2012. Despite this listing, quantified recruitment data are largely lacking for most Atlantic Sturgeon populations, particularly those within the South Atlantic distinct population segment. The objective of this study was to quantify annual recruitment of Atlantic Sturgeon in the Savannah River, Georgia, by estimating annual abundance of age‐1, river‐resident juveniles. During the summers of 2013–2015, we used anchored gill nets and trammel nets to sample juvenile Atlantic Sturgeon throughout the Savannah River estuary. Ages of captured juveniles were determined by using length‐frequency analysis, and abundance of each juvenile age‐class was estimated with Huggins closed‐capture models in RMark. We estimated the Savannah River to contain 528 age‐1 juveniles in 2013, 589 in 2014, and 597 in 2015. The results from this study indicate that the Savannah River population is likely the second largest within the South Atlantic distinct population segment. Future studies are needed to determine the relative importance of the Savannah River as a natural source of recruitment for smaller, more imperiled populations in adjacent rivers. Consequently, we suggest that management efforts continue to prioritize the protection of both the population and the associated critical habitats within the Savannah River estuary.Received April 7, 2016; accepted June 28, 2016 Published online September 23, 2016