Acoustic Tracking of Migrating Bowhead Whales

An acoustic study was conducted off Point Barrow, Alaska in the springs of 1984 and 1985 on the bowhead whale, Balaena mysticetus, during their annual migration. Multi-channel tape recordings were made using arrays of sonobuoys, and whales were acoustically located using a customize hardware and software system specifically designed for performing sophisticated signal analyses. The system was field calibrated out to a distance of 4.5 km. The mean error in range to the source was 2.5%, while the mean error in bearing was 0.4 . At present, the acoustic analysis has concentrated on locating and tracking bowheads in order to census the whales and document their acoustic behavior as they move through and under the arctic ice. Results indicate that whales migrate through the area even during very rough ice conditions when visual observers see very few whales, many whales are more than 2.5 km offshore of the visual observation sites, whales that are within 2.5 km of the visual observers are often never seen, and whales use calls to communicate and maintain the cohesion of the herd.