Call localization of marine mammals using directional autonomous recorders.

Citation

Blackwell, S. B., C. R. Greene Jr, C. S. Nations, T. L. McDonald, A. Thode, and M. A. Macrander (2009). “Call localization of marine mammals using directional autonomous recorders.” In: The Journal of the Acoustical Society of America 125.4, p. 2647. DOI: 10.1121/1.4784130.

Number of Citations: 0

Abstract

Directional sensors of low-frequency acoustic waves have been used by navies in sonobuoys for submarine detection and localization for decades. Composed of an omnidirectional pressure sensor and two horizontal directional elements sensitive to particle motion, they provide information for determining the relative bearing to a sound source without ambiguity. They were adapted for bowhead whale monitoring in the mid-1980s and have been used in autonomous seafloor acoustic recorders since 2000. Applied to the coastal Beaufort Sea north of Alaska, fall bowhead migration was observed in detail during 2007 and 2008, providing a wealth of information on variability in the migration paths of calling whales and the influence of industrial sounds on the locations of calling whales. For example, many calls were detected within about 30 km of seismic survey activities, where received sound pressure levels from airgun pulses were often greater than 140 dB per 1 \(\mu\)Pa. Also, seismic activities were correlated with statistically significant shifts in the whales’ distance from shore, either offshore or inshore. However, interpretation of the results was challenged by the difficulty in distinguishing between a whale that ceases calling and a whale that deflects away from the study area. [Work supported by Shell Oil Co.]