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Hubert J, Demuynck JM, Remmelzwaal MR, Muñiz C, Debusschere E, Berges B, Slabbekoorn H. An experimental sound exposure study at sea: No spatial deterrence of free-ranging pelagic fisha). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:1151-1161. [PMID: 38341743 DOI: 10.1121/10.0024720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/18/2024] [Indexed: 02/13/2024]
Abstract
Acoustic deterrent devices are used to guide aquatic animals from danger or toward migration paths. At sea, moderate sounds can potentially be used to deter fish to prevent injury or death due to acoustic overexposure. In sound exposure studies, acoustic features can be compared to improve deterrence efficacy. In this study, we played 200-1600 Hz pulse trains from a drifting vessel and investigated changes in pelagic fish abundance and behavior by utilizing echosounders and hydrophones mounted to a transect of bottom-moored frames. We monitored fish presence and tracked individual fish. This revealed no changes in fish abundance or behavior, including swimming speed and direction of individuals, in response to the sound exposure. We did find significant changes in swimming depth of individually tracked fish, but this could not be linked to the sound exposures. Overall, the results clearly show that pelagic fish did not flee from the current sound exposures, and we found no clear changes in behavior due to the sound exposure. We cannot rule out that different sounds at higher levels elicit a deterrence response; however, it may be that pelagic fish are just more likely to respond to sound with (short-lasting) changes in school formation.
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Affiliation(s)
- Jeroen Hubert
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | | | | | - Carlota Muñiz
- Marine Observation Centre, Flanders Marine Institute, Oostende, Belgium
| | | | - Benoit Berges
- Wageningen Marine Research, Wageningen University and Research, IJmuiden, The Netherlands
| | - Hans Slabbekoorn
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
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2
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Elmegaard SL, Teilmann J, Rojano-Doñate L, Brennecke D, Mikkelsen L, Balle JD, Gosewinkel U, Kyhn LA, Tønnesen P, Wahlberg M, Ruser A, Siebert U, Madsen PT. Wild harbour porpoises startle and flee at low received levels from acoustic harassment device. Sci Rep 2023; 13:16691. [PMID: 37794093 PMCID: PMC10550999 DOI: 10.1038/s41598-023-43453-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 09/24/2023] [Indexed: 10/06/2023] Open
Abstract
Acoustic Harassment Devices (AHD) are widely used to deter marine mammals from aquaculture depredation, and from pile driving operations that may otherwise cause hearing damage. However, little is known about the behavioural and physiological effects of these devices. Here, we investigate the physiological and behavioural responses of harbour porpoises (Phocoena phocoena) to a commercial AHD in Danish waters. Six porpoises were tagged with suction-cup-attached DTAGs recording sound, 3D-movement, and GPS (n = 3) or electrocardiogram (n = 2). They were then exposed to AHDs for 15 min, with initial received levels (RL) ranging from 98 to 132 dB re 1 µPa (rms-fast, 125 ms) and initial exposure ranges of 0.9-7 km. All animals reacted by displaying a mixture of acoustic startle responses, fleeing, altered echolocation behaviour, and by demonstrating unusual tachycardia while diving. Moreover, during the 15-min exposures, half of the animals received cumulative sound doses close to published thresholds for temporary auditory threshold shifts. We conclude that AHD exposure at many km can evoke both startle, flight and cardiac responses which may impact blood-gas management, breath-hold capability, energy balance, stress level and risk of by-catch. We posit that current AHDs are too powerful for mitigation use to prevent hearing damage of porpoises from offshore construction.
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Affiliation(s)
- Siri L Elmegaard
- Zoophysiology, Dept. of Biology, Aarhus University, 8000, Aarhus, Denmark.
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark.
| | - Jonas Teilmann
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark
| | - Laia Rojano-Doñate
- Zoophysiology, Dept. of Biology, Aarhus University, 8000, Aarhus, Denmark
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark
| | - Dennis Brennecke
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761, Büsum, Germany
| | - Lonnie Mikkelsen
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark
- Norwegian Polar Institute, 9296, Tromsø, Norway
| | - Jeppe D Balle
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark
| | - Ulrich Gosewinkel
- Environmental Microbiology, Dept. of Environmental Science, Aarhus University, 4000, Roskilde, Denmark
| | - Line A Kyhn
- Marine Mammal Research, Dept. of Ecoscience, Aarhus University, 4000, Roskilde, Denmark
| | - Pernille Tønnesen
- Zoophysiology, Dept. of Biology, Aarhus University, 8000, Aarhus, Denmark
| | - Magnus Wahlberg
- Marine Biological Research Centre, Dept. of Biology, University of Southern Denmark, 5300, Kerteminde, Denmark
| | - Andreas Ruser
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761, Büsum, Germany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761, Büsum, Germany
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3
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Graham IM, Gillespie D, Gkikopoulou KC, Hastie GD, Thompson PM. Directional hydrophone clusters reveal evasive responses of small cetaceans to disturbance during construction at offshore windfarms. Biol Lett 2023; 19:20220101. [PMID: 36651028 PMCID: PMC9845968 DOI: 10.1098/rsbl.2022.0101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mitigation measures to disperse marine mammals prior to pile-driving include acoustic deterrent devices and piling soft starts, but their efficacy remains uncertain. We developed a self-contained portable hydrophone cluster to detect small cetacean movements from the distributions of bearings to detections. Using an array of clusters within 10 km of foundation pile installations, we tested the hypothesis that harbour porpoises (Phocoena phocoena) respond to mitigation measures at offshore windfarm sites by moving away. During baseline periods, porpoise movements were evenly distributed in all directions. By contrast, animals showed significant directional movement away from sound sources during acoustic deterrent device use and piling soft starts. We demonstrate that porpoises respond to measures aimed to mitigate the most severe impacts of construction at offshore windfarms by swimming directly away from these sound sources. Portable directional hydrophone clusters now provide opportunities to characterize responses to disturbance sources across a broad suite of habitats and contexts.
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Affiliation(s)
- I. M. Graham
- Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, Cromarty, Ross-shire IV11 8YL, Scotland
| | - D. Gillespie
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife KY16 8LB, Scotland
| | - K. C. Gkikopoulou
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife KY16 8LB, Scotland
| | - G. D. Hastie
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife KY16 8LB, Scotland
| | - P. M. Thompson
- Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, Cromarty, Ross-shire IV11 8YL, Scotland
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4
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Findlay CR, Aleynik D, Farcas A, Merchant ND, Risch D, Wilson B. Auditory impairment from acoustic seal deterrents predicted for harbour porpoises in a marine protected area. J Appl Ecol 2021. [DOI: 10.1111/1365-2664.13910] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Charlotte R. Findlay
- Scottish Association for Marine Science (SAMS) University of the Highlands and Islands Oban UK
| | - Dmitry Aleynik
- Scottish Association for Marine Science (SAMS) University of the Highlands and Islands Oban UK
| | - Adrian Farcas
- Centre for Environment, Fisheries and Aquaculture Science (Cefas) Lowestoft UK
| | - Nathan D. Merchant
- Centre for Environment, Fisheries and Aquaculture Science (Cefas) Lowestoft UK
| | - Denise Risch
- Scottish Association for Marine Science (SAMS) University of the Highlands and Islands Oban UK
| | - Ben Wilson
- Scottish Association for Marine Science (SAMS) University of the Highlands and Islands Oban UK
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5
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Schaffeld T, Ruser A, Woelfing B, Baltzer J, Kristensen JH, Larsson J, Schnitzler JG, Siebert U. The use of seal scarers as a protective mitigation measure can induce hearing impairment in harbour porpoises. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:4288. [PMID: 31893707 DOI: 10.1121/1.5135303] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
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.
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Affiliation(s)
- Tobias Schaffeld
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
| | - Andreas Ruser
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
| | - Benno Woelfing
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
| | - Johannes Baltzer
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
| | | | | | - Joseph G Schnitzler
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, Werftstrasse 6, 25761 Buesum, Germany
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6
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Hermannsen L, Mikkelsen L, Tougaard J, Beedholm K, Johnson M, Madsen PT. Recreational vessels without Automatic Identification System (AIS) dominate anthropogenic noise contributions to a shallow water soundscape. Sci Rep 2019; 9:15477. [PMID: 31664060 PMCID: PMC6820791 DOI: 10.1038/s41598-019-51222-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 09/12/2019] [Indexed: 11/09/2022] Open
Abstract
Recreational boating is an increasing activity in coastal areas and its spatiotemporal overlap with key habitats of marine species pose a risk for negative noise impacts. Yet, recreational vessels are currently unaccounted for in vessel noise models using Automatic Identification System (AIS) data. Here we conduct a case study investigating noise contributions from vessels with and without AIS (non-AIS) in a shallow coastal area within the Inner Danish waters. By tracking vessels with theodolite and AIS, while recording ambient noise levels, we find that non-AIS vessels have a higher occurrence (83%) than AIS vessels, and that motorised recreational vessels can elevate third-octave band noise centred at 0.125, 2 and 16 kHz by 47-51 dB. Accordingly, these vessels dominated the soundscape in the study site due to their high numbers, high speeds and proximity to the coast. Furthermore, recreational vessels caused 49-85% of noise events potentially eliciting behavioural responses in harbour porpoises (AIS vessels caused 5-24%). We therefore conclude that AIS data would poorly predict vessel noise pollution and its impacts in this and other similar marine environments. We suggest to improve vessel noise models and impact assessments by requiring that faster and more powerful recreational vessels carry AIS-transmitters.
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Affiliation(s)
- Line Hermannsen
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark. .,Marine Mammal Research, Department of Bioscience, Aarhus University, Aarhus, Denmark.
| | - Lonnie Mikkelsen
- Marine Mammal Research, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Jakob Tougaard
- Marine Mammal Research, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Kristian Beedholm
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Mark Johnson
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.,Sea Mammal Research Unit, University of St. Andrews, St. Andrews, United Kingdom
| | - Peter T Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
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7
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van Beest FM, Mews S, Elkenkamp S, Schuhmann P, Tsolak D, Wobbe T, Bartolino V, Bastardie F, Dietz R, von Dorrien C, Galatius A, Karlsson O, McConnell B, Nabe-Nielsen J, Olsen MT, Teilmann J, Langrock R. Classifying grey seal behaviour in relation to environmental variability and commercial fishing activity - a multivariate hidden Markov model. Sci Rep 2019; 9:5642. [PMID: 30948786 PMCID: PMC6449369 DOI: 10.1038/s41598-019-42109-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/25/2019] [Indexed: 02/06/2023] Open
Abstract
Classifying movement behaviour of marine predators in relation to anthropogenic activity and environmental conditions is important to guide marine conservation. We studied the relationship between grey seal (Halichoerus grypus) behaviour and environmental variability in the southwestern Baltic Sea where seal-fishery conflicts are increasing. We used multiple environmental covariates and proximity to active fishing nets within a multivariate hidden Markov model (HMM) to quantify changes in movement behaviour of grey seals while at sea. Dive depth, dive duration, surface duration, horizontal displacement, and turning angle were used to identify travelling, resting and foraging states. The likelihood of seals foraging increased in deeper, colder, more saline waters, which are sites with increased primary productivity and possibly prey densities. Proximity to active fishing net also had a pronounced effect on state occupancy. The probability of seals foraging was highest <5 km from active fishing nets (51%) and decreased as distance to nets increased. However, seals used sites <5 km from active fishing nets only 3% of their time at sea highlighting an important temporal dimension in seal-fishery interactions. By coupling high-resolution oceanographic, fisheries, and grey seal movement data, our study provides a scientific basis for designing management strategies that satisfy ecological and socioeconomic demands on marine ecosystems.
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Affiliation(s)
- Floris M van Beest
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark.
| | - Sina Mews
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Svenja Elkenkamp
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Patrick Schuhmann
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Dorian Tsolak
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Till Wobbe
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Valerio Bartolino
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Lysekil, SE-45321, Sweden
| | - Francois Bastardie
- National Institute for Aquatic Resources, Technical University of Denmark, Kemitorvet, Kgs. Lyngby, DK-2800, Denmark
| | - Rune Dietz
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Christian von Dorrien
- Thünen Institute of Baltic Sea Fisheries, Alter Hafen Süd 2, D-18069, Rostock, Germany
| | - Anders Galatius
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Olle Karlsson
- Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Box 50007, SE-104 05, Stockholm, Sweden
| | - Bernie McConnell
- Sea Mammal Research Unit, University of St Andrews, St Andrews, KY16 8LB, United Kingdom
| | - Jacob Nabe-Nielsen
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Morten Tange Olsen
- Evolutionary Genomics Section, Natural History Museum of Denmark, Department of Biology, University of Copenhagen, Øster Voldgade 5-7, DK-1350, Copenhagen K, Denmark
| | - Jonas Teilmann
- Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | - Roland Langrock
- Department of Business Administration and Economics, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
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8
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Findlay CR, Ripple HD, Coomber F, Froud K, Harries O, van Geel NCF, Calderan SV, Benjamins S, Risch D, Wilson B. Mapping widespread and increasing underwater noise pollution from acoustic deterrent devices. MARINE POLLUTION BULLETIN 2018; 135:1042-1050. [PMID: 30300998 DOI: 10.1016/j.marpolbul.2018.08.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 06/07/2018] [Accepted: 08/20/2018] [Indexed: 06/08/2023]
Abstract
Acoustic deterrent devices (ADDs) are used in attempts to mitigate pinniped depredation on aquaculture sites through the emission of loud and pervasive noise. This study quantified spatio-temporal changes in underwater ADD noise detections along western Scotland over 11 years. Acoustic point data ('listening events') collected during cetacean line-transect surveys were used to map ADD presence between 2006 and 2016. A total of 19,601 listening events occurred along the Scottish west coast, and ADD presence was recorded during 1371 listening events. Results indicated a steady increase in ADD detections from 2006 (0.05%) to 2016 (6.8%), with the highest number of detections in 2013 (12.6%), as well as substantial geographic expansion. This study demonstrates that ADDs are a significant and chronic source of underwater noise on the Scottish west coast with potential adverse impacts on target (pinniped) and non-target (e.g. cetaceans) species, which requires further study and improved monitoring and regulatory strategies.
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Affiliation(s)
- C R Findlay
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK.
| | - H D Ripple
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK; 2543 Pine Street, Boulder, CO 80302, USA
| | - F Coomber
- Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Scotland PA75 6NU, UK
| | - K Froud
- Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Scotland PA75 6NU, UK; Glengorm Wildlife Project, Glengorm Estate, Tobermory, Isle of Mull, Scotland PA75 6QE, UK
| | - O Harries
- Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Scotland PA75 6NU, UK
| | - N C F van Geel
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK; Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Scotland PA75 6NU, UK
| | - S V Calderan
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK; Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Scotland PA75 6NU, UK
| | - S Benjamins
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK
| | - D Risch
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK
| | - B Wilson
- Scottish Association for Marine Science (SAMS), University of the Highlands and Islands, Oban, Argyll, Scotland PA37 1QA, UK
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9
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Mikkelsen L, Hermannsen L, Beedholm K, Madsen PT, Tougaard J. Simulated seal scarer sounds scare porpoises, but not seals: species-specific responses to 12 kHz deterrence sounds. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170286. [PMID: 28791155 PMCID: PMC5541550 DOI: 10.1098/rsos.170286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/19/2017] [Indexed: 06/07/2023]
Abstract
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 525 m from the sound source. Contrary to this, seal observations increased during sound exposure within 100 m 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).
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Affiliation(s)
| | - Line Hermannsen
- Department of Bioscience, Aarhus University, Roskilde, Denmark
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Kristian Beedholm
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | | | - Jakob Tougaard
- Department of Bioscience, Aarhus University, Roskilde, Denmark
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