Short-finned pilot whales (Globicephala macrorhynchus) respond to an airgun ramp-up procedure off Gabon

Published source details Weir C.R. (2008) Short-finned pilot whales (Globicephala macrorhynchus) respond to an airgun ramp-up procedure off Gabon. Aquatic Mammals, 34, 349-354.
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This study is summarised as evidence for the following.

	Action	Category
	Use ‘soft start’ procedures to deter marine and freshwater mammals to reduce noise exposure Action Link

Use ‘soft start’ procedures to deter marine and freshwater mammals to reduce noise exposure

A study in 2008 in a pelagic area in the South Atlantic Ocean, Gabon (Weir 2008) found that during a ‘soft start’ procedure using seismic airguns, a pod of short-finned whales Globicephala macrorhynchus changed course and travelled in the opposite direction to the seismic vessel for several minutes before milling at the water surface or travelling parallel to the vessel. Prior to the ‘soft start’ procedure, a pod of 15 short-finned whales was observed travelling steadily northeast for 24 minutes towards the seismic vessel. Nine minutes after the ‘soft start’ procedure commenced, the whales changed course by 180° and travelled southeast away from the vessel. Three minutes later, the whales were observed milling at the water surface or travelling parallel to the vessel as it passed their location within 900 m. In March 2008, a seismic survey was conducted using a single airgun array (consisting of six airgun strings) towed at a depth of 8.5 m and a speed of 4–5 knots y a 90-m vessel. An automated ‘soft start’ procedure was used with additional airgun signals added every 51 seconds during a 30-minute period. The whale pod was located 900 m away when the ‘soft start’ commenced. An observer on board the survey vessel recorded the position and behaviour of the 15 whales for 24 minutes before and 30 minutes during the ‘soft start’ procedure.

(Summarised by: Anna Berthinussen)