Moin MarMam community, My Co-Authors and I are pleased to advertise our recent publication. We investigated the effect of an acoustic deterrent device on harbour porpoise hearing. Such a device can induce a temporary hearing shift, although it is commonly applied as a mitigation tool in order to prevent hearing impairment. Citation: Schaffeld, T., Ruser, A., Woelfing, B., Baltzer, J., Kristensen, J. H., Larsson, J., Schnitzler, J. G. and Siebert, U. (2019). “The use of seal scarers as a protective mitigation measure can induce hearing impairment in harbour porpoises,” J. Acoust. Soc. Am., 146, 4288–4298. Download link: https://asa.scitation.org/doi/full/10.1121/1.5135303 Abstract: Acoustic deterrent devices (ADDs) are used to deter seals from aquacultures but exposure of harbour porpoises (Phocoena phocoena) occurs as a side-effect. At construction sites, by contrast, ADDs are used to deter harbour porpoises from the zone in which pile driving noise can induce temporary threshold shifts (TTSs). ADDs emit such high pressure levels that there is concern that ADDs themselves may induce a TTS. A harbour porpoise in human care was exposed to an artificial ADD signal with a peak frequency of 14 kHz. A significant TTS was found, measured by auditory evoked potentials, with an onset of 142 dB re 1 μPa2s at 20 kHz and 147 dB re 1 μPa2s at 28 kHz. The authors therefore strongly recommend to gradually increase and down regulate source levels of ADDs to the desired deterrence range. However, further research is needed to develop a reliable relationship between received levels and deterrence. Do not hesitate to contact me for further questions. With kind regards, Tobias Schaffeld ………………………………………………………………………………………………………………………………………………………… Tobias Schaffeld Institute for Terrestrial and Aquatic Wildlife Research (ITAW) University of Veterinary Medicine Hannover, Foundation Werftstr. 6 / 25761 Büsum / Germany Tel +49 511 856 8164 / Fax +49 511 856-8181 http://www.tiho-hannover.de/kliniken-institute/institute/institut-fuer-terre... --------------------------------------------------------------------------------------------------------------------------------------