Automated Passive Acoustic Tracking of Dolphins in Free-ranging Pods

Research in passive acoustic detection and localization of marine mammals has largely focused on isolated cases of single or few individuals. However, many marine mammals, such as dolphins, characteristically aggregate in large pods. In addition, dolphins vocalize frequently, emitting broadband clicks and frequency-modulated whistles, which, coupled with a large number of individuals, further complicates the detection and localization problem. Using acoustic data collected on a high-frequency horizontal line array deployed in the Southern California Offshore Range (SCORE), automated tracking of individual dolphins within large pods is achieved by exploiting time differences of arrival and frequency-domain beamforming. Visual observations are used to corroborate acoustic localization results and to describe dolphin vocalization and group behavior patterns.