Behavioral Response of Blue Whales to Active Signals.

• Main Authors: Aburto, A., Rountry, D. J., Danzer, J. L.
• Other Authors: NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
• Format: Text
• Language: English
• Published: 1997
• Subjects: Biological Oceanography; Acoustics; *MARINE BIOLOGICAL NOISE; *AUDITORY ACUITY; *WHALES; SIGNAL PROCESSING; REPETITION RATE; TOWED ARRAYS; RESPONSE(BIOLOGY); ACOUSTIC DATA; LOW FREQUENCY; UNDERWATER SOUND SIGNALS; UNDERSEA SURVEILLANCE; HIGH SENSITIVITY; PE63747N; WUDN903127; baleen whales; Blue whale
• Online Access: http://www.dtic.mil/docs/citations/ADA328274; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA328274

The effects of low frequency sound on marine mammals are not well understood. Although baleen whales are known to produce low frequency sounds, very little is known about their auditory sensitivity. This analysis studied the behavior of blue whales in the vicinity of a loud, low frequency source by evaluating an available data set recorded during a Low Frequency Active (LFA) experiment, the received source levels at the whales were estimated from the known source levels and a Parabolic Equation (PE) propagation model. Element level acoustic data collected with a high gain towed array during the Magellan 2 sea test conducted off the coast of California contained blue and finback whales was spectrally processed to determine the frequency content and repetition rates of their vocalizations. Subarray beam forming was used to cross fix the whale positions and track their movement relative to the active source. The effects of active source transmissions on blue whale vocalization patterns and on their movement relative to the source were analyzed. Estimated received source levels at the whales of 70 to 85 db below full transmit power did not appear to alter the vocalization patterns of the blue whales as determined by analysis of the repetition rates, frequency characteristics, and durations of the whale vocalizations before, during, and after active transmissions.