Use of non-island, shallow nearshore beach environments by Gulf Sturgeon (Acipenser oxyrinchus desotoi) within the Mississippi Sound, USA

Large sub-adult/adult western population Gulf Sturgeon move to barrier islands in winter to feed whereas eastern fish move offshore or to nearshore non-island environments; most small sub-adults/juveniles remain in the estuarine system during winter. To test this, we used an acoustic data set deployed around the Port of Gulfport (hereafter Port footprint, east gate, west gate) within Mississippi Sound. We documented between three and six fish on each receiver totaling 12,285 detections for all 19 receivers between September 2012-May 2013. Only 30% of fish had both a high number of overall detections and a high number of detection days. In contrast, from October 2013-May 2014, between three and nine fish were detected on each receiver but with only 2,371 detections. Five fish (29.4%) had a high number of detections but a reduced number of detection days in the acoustic array; all fish appeared to be transients. Adults, unexpectedly, had the most prevalent occurrence and number of detection days in these shallow, non-island beach environments contrary to our initial hypothesis. Our data suggests annually variable, regional-scale use of beach environments not associated with barrier islands that likely serve as a travel corridor between drainages/offshore barrier islands, or as feeding zones; these movements may enhance the potential for mortality in Mississippi Sound.