Responses of Whales to Experimental Playback of Low- Frequency Sound from the Navy SURTASS LFA
Final rept. 15 Aug 97-30 Sep 98
CORNELL LAB OF ORNITHOLOGY ITHACA NY BIOACOUSTICS RESEARCH PROGRAM
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A three-phased research program was completed to study the effects of SURTASS-LFA sounds on three different species of mysticetes under three different biologically critical contexts. A suite of data collection protocols and techniques were combined to document evidence of response from whales over time scales from a few minutes up to one month, and over distances of approximately 1 to tens of kilometers. Playback experiments were designed to expose whales to received levels of 155 dB re 1 micro-Pa, but it proved difficult to expose animals to levels 150 dB, and few were exposed to levels 140 dB. A whales reactions to the LFA sound varied depending on RL, social context and proximity to the coast. Some whales did respond at levels between 110-150 dB range, but all of the observed responses lasted less than an hour and occurred over ranges of less than several kilometers. None of the observed reactions were considered biologically significant even for received levels as high as 150 dB. These results are surprising. They require critical rethinking of existing assumptions about sound exposure impacts on individuals and populations, and a re-evaluation of existing regulations regarding permissible levels of underwater sound exposure.
- Biological Oceanography