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First published online December 14, 2006
Journal of Experimental Biology 210, 56-64 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02618
Echolocation signals of wild harbour porpoises, Phocoena phocoena
1 Department of Zoophysiology, Institute of Biological Sciences, University
of Aarhus, C. F. Møllers Alle, DK-8000 Aarhus C., Denmark
2 Fjord & Bælt, Margrethes Plads 4, DK-5300 Kerteminde,
Denmark
3 National Environmental Research Institute, Fredriksborgvej 399, DK-4000
Roskilde, Denmark
* Author for correspondence (e-mail: anne.villadsgaard{at}biology.au.dk)
Accepted 25 October 2006
Field recordings of harbour porpoises (Phocoena phocoena) were made in the inner Danish waters with a vertical array of three or four hydrophones. The back-calculated source level ranged from 178 to 205 dB re 1 µPa pp @ 1 m with a mean source level of 191 dB re 1 µPa pp @ 1 m. The maximum source level was more than 30 dB above what has been measured from captive animals, while the spectral and temporal properties were comparable. Calculations based on the sonar equation indicate that harbour porpoises, using these high click intensities, should be capable of detecting fish and nets and should be detectable by porpoise detectors over significantly larger distances than had previously been assumed. Harbour porpoises in this study preferred a relatively constant inter-click interval of about 60 ms, but intervals up to 200 ms and down to 30 ms were also recorded.
Key words: Odontoceti, Phocoena phocoena, biosonar, target detection, click, source level, inter-click interval, bycatch, acoustic monitoring
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L. Blackburn LISTENING IN ON PORPOISES' SIGNALS J. Exp. Biol., January 1, 2007; 210(1): i - ii. [Full Text] [PDF] |
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