NOPP ARU Remote Sensing Survey
Sanctuary maritime archaeologists carried out 9 days of remote sensing survey during Fall 2007 and Winter 2008 on board the research vessel Auk to comply with the sanctuaryís responsibilities under Section 106 of the National Historic Preservation Act (NHPA). Section 106 of the NHPA, requires the sanctuary to take into account the effect of its undertakings on historic properties such as shipwrecks or submerged archaeological sites. The remote sensing project surveyed 29 areas where acoustic recording units (ARU) may be deployed to record marine mammal vocalization.
The sanctuary research vessel Auk was the remote sensing projectís platform.
The project conducted spaced lane side scan sonar surveys covering the ARU deployment locations. Survey lanes, each 1 km long, bracketed each of the ARU deployment locations. Survey lanes were spaced at 30 meter intervals. Lane orientation followed the surrounding topography minimizing depth changes within the survey area. The side scan sonarís range was set to 50 meters assuring 200% sonar coverage of the deployment location. Sonar data was gathered at both 100 and 390 kHz frequencies with a towfish altitude between 5 and 10 meters above the seafloor. All data was recorded with geographic positioning derived from a WAAS-corrected GPS unit.
The side scan sonar uses sound to create images of the
seafloor. Depicted here are furrows created by scallop dredges towed on
top of Stellwagen Bank.
The side scan sonar can also detect fish in the water
column. This image shows a school of fish swimming above a sandy bottom on top of Stellwagen Bank.
Upon completion of the survey, all sonar data was reviewed to identify anomalies. All sonar anomalies were then characterized and classified into three categories: geologic, man-made, or unknown. The side scan sonar survey did not locate any sonar anomalies that had characteristics of a shipwreck or archaeological site that would be affected by the ARU deployment. The National Undersea Research Center for the North Atlantic and Great Lakes at the University of Connecticut supported this project with an equipment loan.