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

TitleAcoustic tracking of sperm whales in the Gulf of Alaska using a two-element vertical array and tags
Publication TypeJournal Article
Year of Publication2013
AuthorsMathias D., Thode A.M, Straley J., Andrews RD
JournalJournal of the Acoustical Society of America
Date Published2013/09
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000330047000070
Keywordsbehavior; clicks; depredation; fin whales; localization; marine mammals; northeast pacific; ocean; physeter-macrocephalus; sea

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. (C) 2013 Acoustical Society of America.

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