Acoustic tracking of sperm whales in the Gulf of Alaska using a two-element vertical array and tags

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Mathias, Delphine, Thode, Aaron, Straley, Jan, Andrews, Russ, D.
• Other Authors: SigmaPhy, Scripps Institution of Oceanography (SIO - UC San Diego), University of California San Diego (UC San Diego), University of California (UC)-University of California (UC)-University of California San Diego (UC San Diego), University of California (UC)-University of California (UC), University of Alaska Southeast (UAS), College of Fisheries and Ocean Sciences (CFOS), University of Alaska Fairbanks (UAF)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph]; [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph]; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Gulf of Alaska; Beaufort Sea; Alaska
• Online Access: https://hal.science/hal-00865948; https://hal.science/hal-00865948/document; https://hal.science/hal-00865948/file/Mathias_2013.pdf; https://doi.org/10.1121/1.4816565

International audience Between 15 and 17 August 2010, a simple two-element vertical array was deployed off the continental slope of Southeast Alaska in 1200 m water depth. The array was attached to a vertical buoy line used to mark each end of a longline fishing set, at 300 m depth, close to the sound-speed minimum of the deep-water profile. The buoy line also served as a depredation decoy, attracting seven sperm whales to the area. One animal was tagged with both a LIMPET dive depth-transmitting satellite and bioacoustic "B-probe" tag. Both tag datasets were used as an independent check of various passive acoustic schemes for tracking the whale in depth and range, which exploited the elevation angles and relative arrival times of multiple ray paths recorded on the array. Analytical tracking formulas were viable up to 2 km range, but only numerical propagation models yielded accurate locations up to at least 35 km range at Beaufort sea state 3. Neither localization approach required knowledge of the local bottom bathymetry. The tracking system was successfully used to estimate the source level of an individual sperm whale's "clicks" and "creaks" and predict the maximum detection range of the signals as a function of sea state.