tixier-habituationtoan-2015.pdf (465.92 kB)
Habituation to an acoustic harassment device (AHD) by killer whales depredating demersal longlines
journal contribution
posted on 2015-06-01, 00:00 authored by Paul Tixier, N Gasco, G Duhamel, C GuinetAcoustic 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.
History
Journal
ICES journal of marine scienceVolume
72Issue
5Pagination
1673 - 1681Publisher
Oxford University PressLocation
Oxford, Eng.Publisher DOI
ISSN
1054-3139eISSN
1095-9289Language
engPublication classification
C Journal article; C1.1 Refereed article in a scholarly journalCopyright notice
2014, International Council for the Exploration of the SeaUsage metrics
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No categories selectedKeywords
acoustic harassment device AHDdepredationkiller whaleslongline fisheriesScience & TechnologyLife Sciences & BiomedicinePhysical SciencesFisheriesMarine & Freshwater BiologyOceanographyPORPOISES PHOCOENA-PHOCOENAORCINUS-ORCASPERM-WHALESPHYSETER-MACROCEPHALUSFISHERY INTERACTIONSBRITISH-COLUMBIAMARINE MAMMALSCROZETCULTURENOISE
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