[MARMAM] New publication: "Simulated seal scarer sounds scare porpoises, but not seals"
lomi at bios.au.dk
Tue Aug 15 12:59:26 PDT 2017
Dear MARMAM readers
We are pleased to announce the recent publication of the following article in Royal Society Open Science:
"Simulated seal scarer sounds scare porpoises, but not seals: species-specific responses to 12 kHz deterrence sounds".
By: Lonnie Mikkelsen, Line Hermannsen, Kristian Beedholm, Peter Teglberg Madsen and Jakob Tougaard.
R. Soc. open sci. 2017 4 170286; DOI: 10.1098/rsos.170286
Open access: http://rsos.royalsocietypublishing.org/content/4/7/170286
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 μPa). 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).
For any questions, please feel free to contact me at: lomi at bios.au.dk<mailto:lomi at bios.au.dk>
Lonnie Mikkelsen, PhD Student
Aarhus University - Department of Bioscience
DK - 4000 Roskilde
Tlf.: +45 87158716
Mobil: +45 20450260
Mail: lomi at bios.au.dk<mailto:lomi at bios.au.dk>
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