Legare, B. and Mace, C., 0000. Mapping and classifying Eastern Oyster (Crassostrea virginica) habitat in Copano Bay, Texas, by coupling acoustic technologies. The Texas coast is characterized by an extensive array of shallow turbid embayments containing expansive oyster habitats and is home to a large Eastern Oyster (Crassostrea virginica) fishery. Mapping habitats in shallow (1–10 m), turbid environments is challenging, since direct visual access to the habitats limited. To quantify the extent of habitats, the integration of remote sensing and GIS technologies is used. The Texas Parks and Wildlife Department coupled two acoustic technologies (sidescan sonar and echosounder) to map habitats within Copano Bay, a 181-km2 shallow water embayment along the mid-Texas coast. Data were collected during 17 days from September 2013 to February 2014 and resulted in 159 km2 of sidescan imagery and 375 km of single beam echosounder data. Individual echosounder transmissions were segmented and processed in Ar...

The detection, classification, and localization of targets or features on the seafloor in acoustic data are critical to many disciplines. This is most important in cases where human safety is in jeopardy, such as hazards to navigation, mitigation of mine countermeasures, or unexploded ordnance. This study quantifies the absolute localization of targets, in the form of inert unexploded ordnance, in very shallow waters (2–3 m) on two intertidal bottom types in a meso-tidal environment (tide range = ~3.0 m). The two sites, a sandy intertidal flat and a mixed sand and gravel beach with abundant cobble-sized material, were seeded at low tide with targets (wax-filled 60-, 81-, 105- and 155-mm, projectile and mortar shells). An RTK-GPS was used to collect positional data for the targets and an unoccupied aerial system (UAS) survey was conducted on both sites. At the next high-tide, a vessel-based acoustic survey was performed, and at the subsequent low tide, the targets were re-surveyed with RTK-GPS. We focus here on the sidescan backscatter from a phase-measuring sidescan sonar (PMSS) and the sources of uncertainty for absolute localization. A total of 1426 calls of acoustic targets were made within the sidescan backscatter data, yielding an accuracy of 0.41 ± 0.26 m, with 98.9% of all calls <1 m from their absolute location. Distance from nadir was the most significant source of uncertainty, and targets between 3–7 m had the lowest uncertainty (0.32 ± 0.23 m) with increasing values toward and away from nadir. Bathymetry and bathymetry-mode backscatter were less useful for the detection and classification of targets compared to sidescan backscatter, but once detected, the accuracy of absolute localization were similar. This is likely due to target calls from these two datasets that were orders of magnitude less and that focused on the larger sized targets, thus more work is needed to better understand these differences. Lastly, the absolute localization of targets detected on sandy and cobble bottoms for all datasets were statistically similar. These acoustic instruments, their datasets, and methods presented herein can better document the absolute localization within acoustic data for many uses in very shallow waters.