Professor Peter Teglberg Madsen

TY - JOUR

T1 - Simulated seal scarer sounds scare porpoises, but not seals

T2 - species-specific responses to 12 kHz deterrence sounds

AU - Mikkelsen, Lonnie

AU - Hermannsen, Line

AU - Beedholm, Kristian

AU - Madsen, Peter Teglberg

AU - Tougaard, Jakob

PY - 2017/7

Y1 - 2017/7

N2 - 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).

AB - 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).

KW - acoustic harassment devices

KW - seal scarer

KW - harbour porpoise

KW - harbour seal

KW - mitigation

KW - pile driving

KW - ACOUSTIC HARASSMENT DEVICES

KW - PHOCOENA-PHOCOENA

KW - HARBOR PORPOISES

KW - UNDERWATER DETECTION

KW - PHOCA-VITULINA

KW - TONAL SIGNALS

KW - EXPOSURE

KW - HEARING

KW - PREDICTIONS

KW - THRESHOLDS

U2 - 10.1098/rsos.170286

DO - 10.1098/rsos.170286

M3 - Journal article

C2 - 28791155

VL - 4

JO - Royal Society Open Science

JF - Royal Society Open Science

SN - 2054-5703

IS - 7

M1 - 170286

ER -