Effects of pingers on the behaviour of bottlenose dolphins

Published source details Leeney R.H., Berrow S., McGrath D., O'Brien J., Cosgrove R. & Godley B.J. (2007) Effects of pingers on the behaviour of bottlenose dolphins. Journal of the Marine Biological Association of the United Kingdom, 87, 129-133.
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This study is summarised as evidence for the following.

	Action	Category
	Use acoustic devices on fishing vessels Action Link
	Use acoustic devices on moorings Action Link

Use acoustic devices on fishing vessels

A controlled study in 2005 of a pelagic area in the Shannon Estuary, western Ireland (Leeney et al. 2007) reported that deploying active ‘continuous’ or ‘responsive’ acoustic devices alongside a boat resulted in common bottlenose dolphins Tursiops truncatus avoiding the boat more frequently than when inactive acoustic devices were deployed. Results are not based on assessments of statistical significance. Dolphins avoided a boat during more trials with active ‘continuous’ devices (3 of 4 trials) and active ‘responsive’ devices (3 of 4 trials) than with inactive ‘continuous’ devices (1 of 4 trials) or inactive ‘responsive’ devices (0 of 1 trial). Active ‘continuous’ or ‘responsive’ acoustic devices were deployed from the back of a 5.4-m rigid inflatable boat for four trials each. Inactive (silent) ‘continuous’ and ‘responsive’ acoustic devices were deployed for four trials and one trial respectively. Dolphin groups were approached to 50 m prior to the deployment of each device. ‘Continuous’ devices (Loughborough University/Aquatech prototype) continuously emitted sounds (<1 second sounds every 5–20 seconds at 5–20 kHz). ‘Responsive’ devices (Aquatec AquaMark) emitted sounds (300 ms sounds at 35–160 kHz) when dolphin clicks were detected by an internal microphone. Dolphin behaviour was observed for four minutes during each of the 13 trials in July 2005.

(Summarised by: Anna Berthinussen)
Use acoustic devices on moorings

A controlled study in 2005 at six pelagic sites in the Shannon Estuary, western Ireland (Leeney et al. 2007) found that using ‘continuous’ acoustic devices on a mooring resulted in lower common bottlenose dolphin Tursiops truncatus echolocation activity compared to when inactive acoustic devices were used, but the difference was not significant for active and inactive ‘responsive’ acoustic devices. The average number of minutes in which dolphin echolocation clicks were detected was lower when ‘continuous’ acoustic devices were active (0 minutes/h; range: 0–0.05 minutes/h) than inactive (0.4 minutes/h; range: 0.2–1.1 minutes/h). The difference was not significant for ‘responsive’ acoustic devices that were active (0 minutes/h; range: 0–0.8 minutes/h) or inactive (0.6 minutes/h; range: 0.3–1.5 minutes/h). An active or inactive (silent) ‘continuous’ or ‘responsive’ acoustic device was randomly deployed at each of six sites for 3–5 x 24 h trials/treatment. ‘Continuous’ devices (Loughborough University/Aquatech prototype) continuously emitted sounds (<1 second sounds every 5–20 seconds at 5–20 kHz). ‘Responsive’ devices (Aquatec AQUAmark) emitted sounds (300 ms sounds at 35–160 kHz) when dolphin clicks were detected by an internal microphone. Devices were attached to a static mooring (line between an anchor and buoy), 5–12 m below the water surface. An acoustic logger recorded dolphin activity alongside the acoustic devices during each of 18 trials in July 2005.

(Summarised by: Anna Berthinussen)