Field experiments show that acoustic pingers reduce marine mammal bycatch in the California drift gill net fishery

Published source details Barlow J. & Cameron G.A. (2003) Field experiments show that acoustic pingers reduce marine mammal bycatch in the California drift gill net fishery. Marine Mammal Science, 19, 265-283.
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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 replicated, randomized, controlled study in 1996–1997 of multiple pelagic sites in the North Pacific Ocean, off the coasts of California and Oregon, USA (Barlow & Cameron 2003; same fishery as Carretta et al. 2008 and Carretta & Barlow 2011) found that fishing nets with acoustic devices attached had fewer entanglements of short-beaked common dolphins Delphinus delphis and California sea lions Zalophus californianus than nets without acoustic devices, but no difference was found for eight other marine mammal species. Entanglement rates were lower for short-beaked common dolphins and California sea lions in fishing nets with acoustic devices attached (both 0.01 entanglements/net) than in nets without acoustic devices (short-beaked common dolphins: 0.07 entanglements/net; California sea lions: 0.05 entanglements/net). Numbers of entanglements did not differ for eight other dolphin, porpoise, whale and seal species (see original paper for data), although sample sizes were small. Between April 1996 and October 1997, ‘drift’ gill nets were deployed at multiple sites (number not reported) and randomly assigned as treatment nets (Dukane NetMark 1000 acoustic devices; 295 nets) or control nets (no acoustic devices; 314 nets). Acoustic devices were spaced 91 m apart and emitted 300 ms pulses with a peak frequency of 10–12 kHz. Observers on board the fishing vessels recorded entangled marine mammals as each of the 609 nets was retrieved.

(Summarised by: Anna Berthinussen)