Spatial and temporal impact of pingers on porpoises

Published source details Carlström J., Berggren P. & Tregenza N.J.C. (2009) Spatial and temporal impact of pingers on porpoises. Canadian Journal of Fisheries and Aquatic Sciences, 66, 72-82.
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This study is summarised as evidence for the following.

	Action	Category
	Use acoustic devices on fishing gear Action Link

Use acoustic devices on fishing gear

A controlled study in 2001 at a pelagic site in the North Atlantic Ocean, off the coast of Scotland, UK (Carlström et al. 2009) found that using acoustic devices on a simulated fishing net reduced the approach distances and echolocation activity of harbour porpoises Phocoena phocoena. The average approach distance of porpoise groups from the ‘net’ was greater when acoustic devices were active (961 m) than inactive (653 m). The average number of echolocation encounters within 0–500 m of the ‘net’ was lower when devices were active (0.1–0.3 encounters/h) than inactive (0.3–0.7 encounters/h). The difference in the number of echolocation encounters was not significant at 750 m (active: 0.36 encounters/h; inactive: 0.42 encounters/h). In April–June 2001, a simulated fishing net (a 700-m lead line) was deployed on the ocean bottom with eight acoustic devices (Dukane NetMark 1000) attached at 100 m intervals. Six devices were active (emitting 300 ms pulse at 10–12 kHz every four seconds) or inactive (silent) for alternating 4-h periods. Two devices at the centre of the ‘net’ were inactive throughout. Acoustic loggers deployed at 0, 250, 500 and 750 m from the ‘net’ recorded porpoise echolocation clicks while acoustic devices were active (total 1,472 h) and inactive (total 1,352 h). Observers on the shore tracked porpoise groups with a theodolite while acoustic devices were active (11 groups during 30 h) and inactive (39 groups during 49 h).

(Summarised by: Anna Berthinussen)