Observations of the movements of humpback whales about an operating seismic survey vessel near Exmouth, Western Australia

As part of a project investigating the interaction of air-gun noise and marine animals, monitoring of migrating humpback whales traversing the track of a seismic vessel was conducted in October 1996. Four separate pods traveling SW in 100–120 m of water were followed as they approached a seismic vessel traveling on an east/west heading and operating a 2678 cui air-gun array every 8 s. The response of pods was to change course at 3–6 km from the vessel so as to pass in front of or behind it. In one instance a single animal was observed moving slowly at 4.2 km NNW of the vessel, then to suddenly accelerate to 10–12 kn on a SW course across the vessel’s bow at a closest range of 1.5 km. It then swam S at 5–10 kn until it was 4 km from the vessel. During the period of rapid swimming the animal stayed close to the surface with the tail flukes often breaking the water, maintaining a 40-s blow interval. The animal then swam steadily SW, eventually stopping and commencing singing on encountering a pod of two animals at 15 km from the still operating seismic vessel. [Work supported by the Energy Research and Development Corporation, Australian Petroleum Production and Exploration Association, and WMC Petroleum.]