Developing the SeaBED AUV to Monitor West Coast Groundfish and Their Habitat

Many of the commercially important species of demersal fish off the U.S. West Coast inhabit rocky habitats of varying relief that are not accessible with traditional survey gears such as bottom trawls. Due to the number and geographic extent of these habitats, and the number of fish stocks that must be assessed on a regular basis, there is a need for cost-effective tools to survey these areas. Over the past several years, we have been developing a SeaBED type AUV (Autonomous Underwater Vehicle) to survey various benthic habitats for fish and biogenic structure-forming invertebrates (e.g., deep-sea corals, sponges). The SeaBED AUV, developed by Hanumant Singh’s lab at Woods Hole Oceanographic Institution, is a bottom tracking AUV that collects high-resolution digital still images of the seafloor and associated fauna. This AUV can be deployed from a variety of vessels ranging from fishing boats to larger oceanographic research vessels.  The AUV is primarily an imaging platform that can provide high-resolution georeferenced images as well as associated oceanographic information such as temperature and salinity. We have configured the AUV with both orthogonal (vertical) and oblique (forward) perspective cameras to provide multiple views to aid in the identification of fish and invertebrates. Utilizing its very precise inertial navigation system, we have also employed the AUV to validate habitat information interpreted from high-resolution multibeam sonar imagery. Results from initial surveys show that many fish species can be identified from the images and that associations between fish and emergent fauna (e.g, deep-sea corals) can be quantified. The ability to collect precisely positioned still images has also facilitated photo-mosaicing techniques that show a broader view of the relationships between fauna and habitat than by individual images alone. Some limitations of this AUV relative to ROVs and manned submersibles are that samples cannot be collected and that there is more limited navigational control of the AUV during missions. This limits opportunistic adjustments while surveying, but also minimizes operator chosen diversions from the survey track. In general AUVs have the advantage of being untethered. This can allow the support vessel to conduct other operations in the vicinity thereby maximizing the data that can be collected per sea day.  Furthermore, the complexity of operating the SeaBED AUV in relatively deep depths up to 1500 meters is generally less than those for tethered devices.