Autonomous underwater vehicle based camera and side-scan sonar assessments of scallop grounds in West Iceland

No abstracts are to be cited without prior reference to the author.

Underwater robots, such as autonomous underwater vehicles (AUVs) equipped with digital and acoustic imaging capabilities, offer a new platform for fishery studies with some known benefits over conventional methods. The proposed approach here was to investigate the use of this survey technique for macrobenthic organisms, specifically the Iceland scallop (Chlamys islandica). A pilot survey in Breidafjordur, western Iceland, was conducted in September 2010, where ten sites were surveyed. Sample locations were previously known scallop dredging sites, with one exception. Two to four parallel transects, 30–50 m apart, were taken at each site, sampling between 400–800 m in length. The AUV was programmed to bottom‐track either at 2.0 or 2.5 m from the seabed. Photos taken from a downward‐facing camera at 2.0 m from the bottom covered approximately 3 m2 of ground area. High‐ and low‐frequency sidescan sonar images were also taken at 10 m and 30 m range, respectively. Image‐enhancement techniques were used to identify and count scallops from the digital photos. Other organisms, such as the common whelk and sea urchins, were also quantifiable. Maps of sidescan sonar images revealed the substrate type at the scallop grounds. Furthermore, it was apparent that higher quality photos were obtained at 2 m from the bottom, where organisms could be identified without difficulty. The imminent objectives are to obtain population density estimates of the scallops within a defined area and relate the distribution and population density to habitat type.