First direct measurements of behavioural responses by Cuvier's beaked whales to mid-frequency active sonar

Stacy Lynn De Ruiter, Brandon L. Southall, John Calambokidis, Walter M. X. Zimmer, Dinara Sadykova, Erin A. Falcone, Ari S. Friedlaender, John E. Joseph, David Moretti, Gregory S. Schorr, Len Thomas, Peter Lloyd Tyack

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Abstract

Most marine mammal­ strandings coincident with naval sonar exercises have involved Cuvier's beaked whales (Ziphius cavirostris). We recorded animal movement and acoustic data on two tagged Ziphius and obtained the first direct measurements of behavioural responses of this species to mid-frequency active (MFA) sonar signals. Each recording included a 30-min playback (one 1.6-s simulated MFA sonar signal repeated every 25 s); one whale was also incidentally exposed to MFA sonar from distant naval exercises. Whales responded strongly to playbacks at low received levels (RLs; 89–127 dB re 1 µPa): after ceasing normal fluking and echolocation, they swam rapidly, silently away, extending both dive duration and subsequent non-foraging interval. Distant sonar exercises (78–106 dB re 1 µPa) did not elicit such responses, suggesting that context may moderate reactions. The observed responses to playback occurred at RLs well below current regulatory thresholds; equivalent responses to operational sonars could elevate stranding risk and reduce foraging efficiency.
Original languageEnglish
Pages (from-to)1-5
Number of pages5
JournalBiology Letters
Volume9
Issue number4
Early online date3 Jul 2013
DOIs
Publication statusPublished - 2013

Keywords

  • Acoustic disturbance
  • Avoidance response
  • Anthropogenic noise
  • Mid-frequency active sonar
  • Military
  • Ziphius cavirostris

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