Abstract

This research cruise was focused on identifying hardbottom habitat along the outer shelf of the De Soto Canyons eastern margin. These benthic habitats support a wide range of benthic communities and essential fish habitat. The distribution of these habitats are poorly known, making impacts from events such as the DwH oil spill difficult to assess. Based on existing maps of the seafloor, as well as reconnaissance mapping of this area in 2012, we mapped the seafloor in areas that appear most likely to contain high-relief bottom topography a key ingredient for mesosphotic coral ecosystems. We used a Teledyne-Benthos C3D interferometric sidescan sonar that produces high-quality 200 kHz backscatter imagery and sub-meter resolution swath bathymetry. Swath coverages are 400-500 m for the backscatter and 7-8 times towfish altitude (or sidescan limit) for the bathymetry. We also be acquired acoustic imaging of the water column and seafloor using the EK60 echo sounder on the WBII. The EK60 can be used for fish stock assessment and can be directly correlated with bottom type mapped by the C3D. We also conducted CTD casts for sound velocity profiles and water sampling.