Measuring responses of harbour seals to potential aversive acoustic mitigation signals using controlled exposure behavioural response studies

• Published in: Aquatic Conservation: Marine and Freshwater Ecosystems
• Main Authors: Gordon, Jonathan, Blight, Clint, Bryant, Ed, Thompson, Dave
• Other Authors: NERC, University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Behaviour; Coastal; Disturbance; Engineering; Mammals; Renewable energy; Tracking; GC Oceanography; QH301 Biology; DAS; SDG 7 - Affordable and Clean Energy; SDG 14 - Life Below Water; GC; QH301; Orca; Orcinus orca; Phoca vitulina
• Online Access: http://hdl.handle.net/10023/20569; https://doi.org/10.1002/aqc.3150

This work was funded by Scottish Government's Marine Mammal Scientific Support Research Programme MMSS/001/11 and UK's Natural Environment Research Council (NERC), and Department for Environment Food and Rural Affairs (NE/J004251/1) and NERC (National Capability SMRU1001). 1. Some anthropogenic activities pose acute risks for marine species. For example, pile driving could damage the hearing of marine mammals while underwater explosions can also result in physical damage or death. Effective mitigation is required to reduce these risks, but the exclusion zones specified in regulations can extend over hundreds or thousands of metres and seals pose particular problems because they are difficult to detect at sea. 2. Aversive sound mitigation aims to exclude animals from high‐risk areas before dangerous activities take place by broadcasting specific acoustic signals. Field research is needed to identify signals that might be effective in eliciting short‐term avoidance by marine species such as harbour seals (Phoca vitulina). A series of controlled‐exposure experiments (CEEs) were undertaken to measure seal movements in response to acoustic deterrent devices (ADD) and predator calls, and to assess the effectiveness of candidate signals for aversive sound mitigation. 3. Seals were fitted with UHF/GPS transmitters providing continuous high‐resolution tracks and real‐time transmissions of their locations. A tracking/playback vessel located seals at sea and transmitted either ADD signals or orca (Orcinus orca) calls over a range of distances while seals were foraging or moving between sites. Behaviour before, during and after exposure was analysed to assess responses. 4. One‐hundred and ten CEEs were assessed as being of at least ‘adequate’ quality. Of the 71 adequate trials with the Lofitech ADD, all 38 at ranges of <1 km (predicted received level 134.6 dB RMS re 1 μPa) elicited a response. The maximum response range was 3123 m (predicted RL: 111 dB RMS re 1 μPa). However, the responses observed did not always ...