Whale acoustic activity and dive behavior before, during and after sound playback experiments.

<p>Deep foraging dives of one beaked whale tagged in 2007 (A–C) and another beaked whale tagged in 2008 (E–G) with the time of each dive indicated on the x-axis. The segment of the dive when the whale was clicking is indicated by coloring the dive profile blue. (A) This first dive after tagging was a pre-exposure dive. (B) This second dive after tagging involved playback of the MFA sonar stimulus, with slowly increasing level of playback. The red dots mark the received sound pressure level of the playback signal as recorded on the whale (in dBrms re 1 µPa averaged over a 200 msec window). (C) This third dive involved playback of killer whale (ORCA) sounds. The received level of the ORCA playback signal indicated by the red dots is the third octave band with the most energy averaged over a 200 msec. (D) The horizontal component of the motion of the tagged whale exposed to playbacks in 2007 is plotted in the dark gray and colored lines. Deep foraging dives are marked in green, and playback sound exposure is indicated in red. Tracks of three other beaked whales tagged during baseline conditions when no sonar was transmitting are shown in light gray for comparison. All tracks are presented with respect to the same arbitrary start position at (0, 0). Note that none of the baseline tracks contain segments as linear as the avoidance response of the whale after playback of killer whale sounds. (E–F) These first two dives after tagging in 2008 were pre-exposure dives. (G) The third dive after tagging in 2008 involved playback of the PRN sound stimulus, with slowly increasing level of playback. The red dots mark the increasing received sound pressure level of the playback signal (in dBrms re 1 µPa averaged over a 200 msec window).