Differentiation of Narrow-band High-frequency Signals Produced by Odontocetes
- Author(s): Teller, Grace
- Advisor(s): Baumann-Pickering, Simon
- et al.
ABSTRACT OF THE THESIS
Differentiation of Narrow-Band High Frequency-Signals
Produced by Odontocetes
Grace Elizabeth Teller
Master of Science in Oceanography
University of California, San Diego, 2016
Simone Baumann-Pickering, Chair
Passive acoustics are an excellent method for studying marine mammals through echolocation. The data captured in acoustic recordings has the ability to relay information about density, distribution, and behavior over long time periods. The ability to understand, monitor, and predict these factors is imperative to the conservation and management of marine mammals. In order to utilize passive acoustics effectively, researchers must first become well acquainted with how to distinguish acoustic emissions.
The northeast Pacific Ocean is home to at least four species of odontocetes producing narrow-band high-frequency (NBHF) signals. Utilizing bottom moored passive acoustics these signals were recorded at three sites. Eight unknown click types of NBHF echolocation clicks resulted with varying spectral and temporal features that were used in discriminating harbor porpoise (Phocoena phocoena), Dall’s porpoise (Phocoenoides dalli), and dwarf and pygmy sperm whales as a group (Kogia spp). Associations were made based on relative dominance by click type at a site and known habitat and ecology of each species in question. Based on this association, harbor porpoise signals are best described by a notch position lower than the peak. Bimodal inter-click interval (ICI) below 40 ms and around 135 ms indicates a potential for this species to switch between long and short range sensing. Possible Dall’s porpoise and Kogia spp. signals both maintain a spectral shape where the notch is positioned after the peak frequency. Distinguishing these species may best be done by the position of energy onset above and below 100 kHz and ICI around 40 ms or 80 ms, respectively.