NEW SOCAL-BRS PAPER ON BEAKED WHALE RESPONSES TO SOUND EXPOSURE
A second paper from the SOCAL-BRS project was published today as well. This paper (in Biology Letters) presents results for the responses of beaked whales to both controlled and incidental exposure to mid-frequency sonar signals. The reference for the paper is:
DeRuiter SL, Southall BL, Calambokidis J, Zimmer WMX, Sadykova D, Falcone EA, Friedlaender AS, Joseph JE, Moretti, D, Schorr GS, Thomas L, Tyack PL. 2013 First direct measurements of behavioural responses by Cuvier’s beaked whales to mid-frequency active sonar. Biol Lett 9: 20130223. http://dx.doi.org/10.1098/rsbl.2013.0223
This paper is available through Open Access as well at: http://rsbl.royalsocietypublishing.org/content/9/4/20130223.full
The abstract for the paper is given here:
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 micro Pa): 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 micro Pa) 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.