Risk versus reward: Interactions, depredation rates, and bycatch mitigation of dolphins in demersal fish trawls

Published source details Santana-Garcon J., Wakefield C.B., Dorman S.B., Denham A., Blight S., Molony B.W. & Newman S.J. (2018) Risk versus reward: Interactions, depredation rates, and bycatch mitigation of dolphins in demersal fish trawls. Canadian Journal of Fisheries and Aquatic Sciences, 75, 2233-2240.
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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 2013 of a pelagic area in the Indian Ocean, northwest Australia (Santana-Garcon et al. 2018) found that trawl nets with acoustic devices attached had a similar number and duration of common bottlenose dolphin Tursiops truncatus interactions compared to trawl nets without acoustic devices. Average daily interaction rates of dolphins with trawl nets did not differ significantly between nets with acoustic devices (0.7 interactions/minute) and without (0.4 interactions/minute). The average duration of interactions also did not differ significantly with acoustic devices (1.7 minutes) or without (1.3 minutes). Three commercial vessels carried out 14 trawls with acoustic devices attached to trawl nets and 17 trawls without acoustic devices. Dolphin Dissuasive Devices (emitting random frequencies between 2 and 500 kHz) were attached on either side of an underwater video camera installed within each trawl net. All trawls were carried out during the day with a single stern trawl net towed close to the seabed in water 50–100 m deep. Video cameras recorded dolphin interactions with the nets during each of the 31 trawls in January–February 2013.

(Summarised by: Anna Berthinussen)