Insights into underwater behavior and vocalizations of blue and fin whales from attachments of acoustic recording tags

Abstract

The underwater behavior and vocalizations of blue and fin whales in the northeast Pacific were examined using three types of electronic archival tags attached with suction cups. The bulk of the attachments were of the ‘‘Bioacoustic Probe,’’ a commercially available acoustic recording tag developed by Greeneridge Sciences under ONR support. We completed more than 30 deployments of this tag between 2002 and 2004 at multiple locations off California and in the Sea of Cortez, Mexico. Acoustic data recorded by the tags were used to investigate: (1) vocalizations made by the tagged subject whale and nearby animals; (2) anthropogenic noise to which the subject was exposed, including airguns and vessel noise; and (3) the variability of flow noise, which indicated the relative speed of the subject through the water. Results to date have revealed a number of new findings on blue whale vocalizations, including that only a small proportion of blue whales are producing regular calls, that more blue whales may be producing calls irregularly than regularly, and that callers are males. The new data have also clarified the behavioral context in which calling takes place. [Work supported by ONR, SERDP, CNO N45.]