Habituation to an acoustic harassment device (AHD) by killer whales depredating demersal longlines

Tixier, Paul, Gasco, Nicolas, Duhamel, Guy and Guinet, Christophe 2015, Habituation to an acoustic harassment device (AHD) by killer whales depredating demersal longlines, ICES journal of marine science, vol. 72, no. 5, pp. 1673-1681, doi: 10.1093/icesjms/fsu166.

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Title Habituation to an acoustic harassment device (AHD) by killer whales depredating demersal longlines
Author(s) Tixier, PaulORCID iD for Tixier, Paul orcid.org/0000-0002-7325-3573
Gasco, Nicolas
Duhamel, Guy
Guinet, Christophe
Journal name ICES journal of marine science
Volume number 72
Issue number 5
Start page 1673
End page 1681
Total pages 9
Publisher Oxford University Press
Place of publication Oxford, Eng.
Publication date 2015-06-01
ISSN 1054-3139
Keyword(s) acoustic harassment device AHD
killer whales
longline fisheries
Summary Acoustic harassment devices (AHDs) have been increasingly implemented in various fisheries that suffer significant losses caused by odontocete depredation. However, the efficacy of AHDs to deter odontocetes from fishing gear remains poorly investigated. To determine the effectiveness of AHDs in deterring depredation, we experimentally tested a high amplitude device (195 dB re 1 μPa 6.5 kHz 1 m from the source) from a Patagonian toothfish Dissostichus elegenoides longliner operating off the Crozet Islands, while it was subjected to heavy depredation by killer whales Orcinus orca. This species usually depredates longlines within a 10- to 300-m range from the vessel, as they only have access to fishing gear during hauling. We expected this distance to increase in response to the acoustic disturbance created by the AHD. The distances of 29 killer whales from the vessel (n = 1812 records) were collected during phases of AHD activation and phases during which the AHD was turned off. Two multiexposed killer whale social units fled over 700 m away from the vessel when first exposed to the AHD. However, they remained within a 10- to 300-m range and depredated longlines again past the third and seventh exposures, respectively, showing an insignificant behavioural response to further activations of the AHD. When tested through generalized linear mixed models, the effect of AHD activation was only significant when killer whales were first exposed to the device. However, the effect disappeared after successive exposures suggesting that killer whales became habituated to the AHD and may sustain potentially harmful hearing disturbance to access the resource made available by longliners. In addition to raising significant conservation concerns, this rapid return of initial depredation behaviour strongly suggests that AHDs are ineffective at deterring depredating killer whales, and that fisheries should favour the use of other mitigation techniques when facing repeated depredation by this species.
Language eng
DOI 10.1093/icesjms/fsu166
Field of Research 070403 Fisheries Management
060201 Behavioural Ecology
MD Multidisciplinary
HERDC Research category C1.1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2014, International Council for the Exploration of the Sea
Persistent URL http://hdl.handle.net/10536/DRO/DU:30103423

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