Waveguide propagation allows range estimates for north pacific right whales in the bering sea

  • Sean M. Wiggins Scripps Institution of Oceanography, 9500 Gilman Drive-0205, San Diego, CA 92093-0205
  • Mark A. McDonald Whale Acoustics, 11430 Rist Canyon Road, Bellvue, CO 80512
  • Lisa M. Munger Scripps Institution of Oceanography, 9500 Gilman Drive-0205, San Diego, CA 92093-0205
  • Sue E. Moore NOAA, National Marine Mammal Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115
  • John A. Hildebrand Scripps Institution of Oceanography, 9500 Gilman Drive-0205, San Diego, CA 92093-0205
Keywords: Acoustic waves, Modal analysis, Parameter estimation, Sediments, Waveform analysis, Waveguides, Acoustic recording, Sediment density, Waveguide propagation, Whales

Abstract

The shallow and uniform water depth of the eastern Bering Sea shelf results in an acoustic waveguide. Propagation within this waveguide produces waveform dispersion which is dependent upon range. We present a means for using dispersed waveforms to determine range to calling whales from a single autonomous acoustic recording instrument. The predominant North Pacific right whale (Eubalaena japonica) call is frequency upswept from about 90 Hz to around 160 Hz and lasts approximately 1 s. The regional bathymetry of the eastern Bering Sea middle shelf is relatively uniform and shallow (∼70 meters deep). This geometry provides a plane-layered waveguide in which right whale upswept calls can be detected at ranges over 50 km and have multiple modal arrivals that become dispersed, displaying different propagation velocities for different frequencies. Dispersion characteristics of modal arrivals are dependent on the calling whale's depth, the receiver's depth, the water depth, the range from caller to receiver, and various environmental parameters including water and sediment density and sound velocity. A model of sound propagation for the eastern Bering Sea middle shelf is developed from right whale call dispersion recorded on sonobuoys and seafloor acoustic recording packages, using individual calls recorded at multiple instruments. After development of the model, waveform dispersion allows estimation of caller range based on single instrument recordings. Estimating range between instrument and calling whales provides a means to estimate minimum abundance for the endangered North Pacific right whale.
Published
2004-06-01
How to Cite
1.
Wiggins SM, McDonald MA, Munger LM, Moore SE, Hildebrand JA. Waveguide propagation allows range estimates for north pacific right whales in the bering sea. Canadian Acoustics [Internet]. 2004Jun.1 [cited 2019Dec.10];32(2):146-54. Available from: //jcaa.caa-aca.ca/index.php/jcaa/article/view/1598
Section
Proceedings of the Acoustics Week in Canada