Aarhus University Seal / Aarhus Universitets segl

Professor Peter Teglberg Madsen

Simulated seal scarer sounds scare porpoises, but not seals: species-specific responses to 12 kHz deterrence sounds

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    Final published version, 1.03 MB, PDF document

DOI

Acoustic harassment devices (AHD) or 'seal scarers' are used extensively, not only to deter seals from fisheries, but also as mitigation tools to deter marine mammals from potentially harmful sound sources, such as offshore pile driving. To test the effectiveness of AHDs, we conducted two studies with similar experimental set-ups on two key species: harbour porpoises and harbour seals. We exposed animals to 500 ms tone bursts at 12 kHz simulating that of an AHD (Lofitech), but with reduced output levels (source peak-to-peak level of 165 dB re 1 mu Pa). Animals were localized with a theodolite before, during and after sound exposures. In total, 12 sound exposures were conducted to porpoises and 13 exposures to seals. Porpoises were found to exhibit avoidance reactions out to ranges of 525m from the sound source. Contrary to this, seal observations increased during sound exposure within 100m of the loudspeaker. We thereby demonstrate that porpoises and seals respond very differently to AHD sounds. This has important implications for application of AHDs in multi-species habitats, as sound levels required to deter less sensitive species (seals) can lead to excessive and unwanted large deterrence ranges on more sensitive species (porpoises).

Original languageEnglish
Article number170286
JournalRoyal Society Open Science
Volume4
Issue7
Number of pages13
ISSN2054-5703
DOIs
Publication statusPublished - Jul 2017

    Research areas

  • acoustic harassment devices, seal scarer, harbour porpoise, harbour seal, mitigation, pile driving, ACOUSTIC HARASSMENT DEVICES, PHOCOENA-PHOCOENA, HARBOR PORPOISES, UNDERWATER DETECTION, PHOCA-VITULINA, TONAL SIGNALS, EXPOSURE, HEARING, PREDICTIONS, THRESHOLDS

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