ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4aAB5. Using combined acoustic tracking and visual observation techniques to study humpback whales.

Adam S. Frankel

Christopher W. Clark

Cornell Biacoust. Res. Program, 159 Sapsucker Woods Rd., Ithaca, NY 14850

The technique of acoustic location was combined with visual tracking and behavioral observation to study humpback whales on the winter mating grounds in Hawaii. The behavior and movements of nonvocalizing whales and singers could be studied simultaneously. Social interactions that had not been previously described were observed. These included affiliations of singers and nonsingers while the singer continued to sing. Visual tracking also allowed the comparison of visual and acoustic locations to verify the accuracy of the acoustic locations. Acoustic location allowed the simultaneous tracking of several humpback singers, and their relative distribution and orientations were examined. Results indicate that song mediates inter-singer separation and that 4 km was the preferred minimum spacing between singers off Hawaii. Humpbacks have been described as being distributed within the 100 fathom contour while on the mating grounds. However, singers were acoustically located up to 13 km offshore in water as deep at 305 fathoms. While singers are typically described as stationary, combined tracking techniques revealed singer speeds of up to 3.6 km/h. In conclusion, the combination of acoustic and visual tracking provided a more comprehensive view of humpback whale behavior and distribution than either technique separately.