Using Imagery from the Seabed AUV to Determine Fish, Invertebrate and Habitat Associations

The SeaBED bottom-tracking autonomous underwater vehicle is used to conduct surveys to quantify fish, invertebrate and habitat associations.  The AUV sampling platform provides stereo downward-looking images and a forward-looking image used primarily for better faunal identification.  The downward-looking images are particularly useful for making accurate distance measurements between fish and associated geological structures or structure-forming invertebrates.  In addition, the overhead view also provides a unique perspective from which to observe usage of the structures as habitat.  We will present several example analyses using overhead imagery to quantify potential groundfish habitat associations.  Investigations in an area with high sponge density showed use of sponges by rockfish as apparent refugia.  We were able to quantify the relative distances between rockfish and a variety of structures to determine potential specific associations. In a recent survey of an area with high concentrations of large shortspine thornyhead, we are using images from the AUV to quantify their spatial distribution relative to nearby structure forming invertebrates. The AUV has photo mosaicking capability providing us with the capacity to stitch images together in order to see structure and fish relationships in a view of the larger survey site, giving a unique perspective on fish/ habitat associations.