Estimating the density of Blainville's beaked whale (Mesoplodon densirostris) in the Tongue of the Ocean (TOTO) using passive acoustics

Techniques to detect and localize marine mammals including Blainville's beaked whales (Mesoplodon densirostris) using the bottom-mounted hydrophones of the Atlantic Undersea Test and Evaluation Center have been developed. A series of verification tests using these passive acoustics techniques to determine the presence and position of vocalizing animals are being conducted. These acoustic "sightings" are verified by a team of surface observers. Based on Woods Hole Oceanographic Institution tag data and the ongoing verification tests, vocalizations associated with M. densirostris appear to be distinct in type, frequency, and repetition rate. Group size estimates have been derived from these tests and from previous long-term observations. By acoustically mapping the distribution of animals and applying estimates of average group size an initial density estimate for M. densirostris is derived