Behavioral responses of humpback whales to seismic air guns

A study of the response of humpback whales to seismic air guns is being conducted in Australian waters and two of four major experiments have been completed. It aims to assess the impact of seismic surveys on the whales and the effectiveness of ramp-up in mitigation. In separate trials, whales were exposed to a 20 cu in air gun, ramp-up in level from 20 cu in to 440 cu in with an air gun array, and a 'hard start' of 140 cu in. Whales were tracked using theodolites on high points ashore and behavioral observations were made from these points and from three small vessels and the source vessel. Vocalising whales were tracked with an array of hydrophones. DATGs were attached to some whales. Observations were made before, during and after exposure. Trials exposing whales to air gun treatments were balanced by controls without air guns firing. Characterization of the sound field throughout the area and the exposure at each whale were determined from propagation measurements and recordings on the hydrophone arra...