A Novel Approach For Identifying Concentration Areas Of Reproductively Mature Atlantic Sturgeon and Assessing The Impacts Of Targeted Anchored Gillnetting

Worldwide, sturgeons are recognized as one of the most imperiled groups of organisms. In 2012, Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were listed under the ESA due to concerns over population declines.  In June 2013, through a combination of passive mobile telemetry and high-resolution side-scan sonar, we assessed the distribution of reproductively mature Atlantic sturgeon in a 10km reach of the Hudson River, near Hyde Park, New York.  Atlantic sturgeon were concentrated in three distinct regions. In the region of highest density, which was previously unknown, we conducted pre, during, and post surveys to evaluate the distribution and relative abundance of sturgeon during targeted gillnetting sampling efforts.  We collected a total of nine reproductively mature Atlantic sturgeon, of which, the vast majority were imaged.  Over the course of netting activities, the distribution of Atlantic sturgeon transitioned from small clusters to a more uniformly dispersed state. We also documented a corresponding decrease in relative abundance in the study area during sampling.  We recommend the use of high-resolution side-scan sonar to identify concentration areas of reproductively mature Atlantic sturgeon.  Furthermore, when developing population estimates, the impact of sampling activities on sturgeon distribution and relative abundance should be considered.