Aerial surveys and satellite and archival tags were used to test the effect of the ATOC sound source on marine mammals around the Pioneer Seamount 85 km west of San Francisco, California. Control surveys were flown at least 48 h after the end of any previous transmission cycle and experimental surveys were flown after at least 24 h of sound transmissions. Sound transmissions consisted of 20‐min periods of 195‐dB, that is, 1‐μP transmission repeated very 4 h. Most commonly sighted species by group were: (1) mystecetes: humpback whale (372 sightings), (2) large odontocetes: sperm whale (337 sightings), (3) small odontocetes: Pacific white‐sided dolphin (306 sightings), and (4) pinnipeds: California sea lion (167 sightings). Although there were no significant differences in the number of sightings when the sound source was on or off, both humpback and sperm whales were generally seen farther from the sound source during experimental versus control surveys (p<0.01). The highest intensity of sound measured on tags carried by elephant seals during transmissions ranged from 118–137 dB for 60–90 Hz compared to ambient levels of 87–107 dB (60–90 Hz). On a gross level, animals did not alter return track or go to the surface, and often continued to dive closer to the sound source if on the descending segment of a dive evident. Some animals with the highest levels of exposure showing no effects while two animals showing minor changes in diving pattern had exposure levels greater than 132 dB. [Work supported by the Strategic Environmental Research and Development Program through RPA and the Office of Naval Research.]
Costa, D. and J. Calambokidis. 1999. Marine mammal research program for the Pioneer Seamount ATOC experiment. Invited presentation (by JC) to the Acoustical Society of America, Columbus, OH, 4 November 1999. Journal of the Acoustical Society of America 106:2280.