Air Gun Arrays as Noise Sources: Output, Impact Zones, and Frequency Content

The widespread use of powerful, low-frequency air gun pulses for seismic seabed exploration has raised concern about their potential negative effects on marine wildlife. An array of air guns creates a downward-directed, low-frequency pulse with most energy concentrated around 50 Hz and a back-calculated, broadband source level between 230 and 260 dB re 1 pPa (0 peak) with ocean-traversing potential. This talk reports the sound exposure levels recorded on acoustic tags attached to eight sperm whales at ranges between 1.4 and 12.6 km from controlled air gun array sources operated in the Gulf of Mexico and discusses the implications for sound metrics, exposure zones, and impacts on marine mammals.