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ESR 28:97-108 (2015)  -  DOI:

False killer whale and short-finned pilot whale acoustic identification

Simone Baumann-Pickering1,*, Anne E. Simonis1, Erin M. Oleson2, Robin W. Baird3, Marie A. Roch1,4, Sean M. Wiggins

1Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0205, USA
2Pacific Islands Fisheries Science Center, NOAA, 2570 Dole Street, Honolulu, Hawai‘i 96822, USA
3Cascadia Research Collective, 218 1/2 W 4th Ave., Olympia, WA 98501, USA
4Department of Computer Science, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-7720, USA
*Corresponding author:

ABSTRACT: False killer whales Pseudorca crassidens and short-finned pilot whales Globicephala macrorhynchus are known to interact with long-line fishing gear in Hawaiian waters, causing economic loss and leading to whale injuries and deaths. The main Hawaiian Islands’ insular population of false killer whales is listed as endangered and the offshore population is considered ‘strategic’ under the Marine Mammal Protection Act due to relatively high bycatch levels. Discriminating between these species acoustically is problematic due to similarity in the spectral content of their echolocation clicks. We used passive acoustic monitoring along with data from satellite tags to distinguish signals from these 2 species. Acoustic encounters recorded with autonomous instruments offshore of the islands of Hawai‘i and Kaua‘i were matched with concurrent and nearby location information obtained from satellite tagged individuals. Two patterns of echolocation clicks were established for the 2 species. The overall spectral click parameters were highly similar (22 kHz peak and 25 kHz center frequency), but false killer whales had shorter duration and broader bandwidth clicks than short-finned pilot whales (225 µs, 8 kHz [-3 dB bandwidth] and 545 µs, 4 kHz, respectively). Also, short-finned pilot whale clicks showed distinct spectral peaks at 12 and 18 kHz. Automated classification techniques using Gaussian mixture models had a 6.5% median error rate. Based on these findings for echolocation clicks and prior published work on whistle classification, acoustic encounters of false killer whales and short-finned pilot whales on autonomous instruments should be identifiable to species level, leading to better long-term monitoring with the goal of mitigating bycatch.

KEY WORDS: Echolocation · Classification · False killer whale · Passive acoustic monitoring · Satellite tagging

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Cite this article as: Baumann-Pickering S, Simonis AE, Oleson EM, Baird RW, Roch MA, Wiggins SM (2015) False killer whale and short-finned pilot whale acoustic identification. Endang Species Res 28:97-108.

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