High-frequency acoustic tracking of odontocetes at the Southern California Offshore Range (SCORE)

Abstract

The SCORE site, located near San Clemente Island, is known to be abundant in marine mammals, and is the site of frequent naval operations, making it an ideal site to study what impact man-made activities may have upon these creatures. In August 2004, an experiment was performed to collect both visual and acoustic observations of odontocetes at the SCORE site. Odontocete vocalizations consist of clicks and whistles. The clicks are very wideband (often 100 kHz), so times of arrival can be measured with extremely high resolution, which makes clicks attractive waveforms for multipath ranging and depth estimation. Although the whistles are narrowband, their fundamental frequency often ranges over tens of kilohertz, so these too can be processed as if they were wideband. We will present results of processing excerpts from several weeks of data recorded on a high-frequency horizontal line array deployed from the FLIP research vessel. Bearing tracks of individuals and groups from a number of different species will be correlated and compared with visual observations. In addition, we will discuss the possibilities for range and depth estimates derived from the multipath arrivals observed in the clicks and whistles.