A Novel Approach to Surveying Sturgeon Using Side-Scan Sonar and Occupancy Modeling

Technological advances represent opportunities to enhance and supplement traditional fisheries sampling approaches. Use of hydroacoustic technologies, such as side-scan sonar, are becoming more widespread.  Side-scan sonar has advantages over traditional techniques, such as the ability to sample large areas efficiently and potential to survey fish without physically handling them – important for species of conservation concern, such as endangered sturgeons.  Our objective is to design an efficient survey methodology for sampling Atlantic sturgeon using side-scan sonar and develop methods to analyze these data.  We surveyed six rivers in North and South Carolina, thought to contain varying abundances of sturgeon, using a combination of side-scan sonar, telemetry, and video cameras (to sample jumping sturgeon). We surveyed lower reaches of each river, near the saltwater/freshwater interface, on three occasions (generally successive days) and used an occupancy modeling approach to analyze these data.  We were able to detect sturgeon in five of six rivers using these methods.  Side-scan sonar was effective in detecting sturgeon, with estimated detection probabilities ranging from 0.2-0.5 and occupancy estimates for individual rivers ranging from 0.0-0.8.  Future work with side-scan sonar will involve assessing sturgeon habitat and abundance in different river systems.