Abstract
Increasingly, the use of man-made sound (‘acoustic deterrents’) is sought to lessen humanwildlifeconflicts by discouraging predation, displacing species away from harmful stimuli,
or reducing damage to property and resources. In the marine environment, Acoustic Deterrent
Devices (ADDs) are used by the aquaculture industry globally. ADDs produce loud, mid- to
high-frequency noise to deter pinnipeds from predating on caged finfish. However, the
widespread and long-term use of these devices in coastal environments could pose
considerable risks for target (pinnipeds) and non-target (e.g., cetaceans) species which also
inhabit areas adjacent to aquaculture. This thesis contributes new knowledge towards our
understanding of the risks posed to marine mammals from exposure to ADD noise. An
energy-flux acoustic propagation model was used to demonstrate that ADD noise is a
significant contributor to coastal soundscapes on the west coast of Scotland, able to propagate
far beyond the source and aquaculture cages. Modelling showed that both harbour porpoises
and harbour seals would be repeatedly exposed to ADD noise, with predicted noise levels in
some instances exceeding thresholds which could result in either a temporary or permanent
hearing impairment. A habitat modelling approach indicated that ADD noise was also a
significant driver of harbour porpoise distributions on this coastline. Highlighting that
animals could be displaced from, seek out or remain within disturbed habitats. These results
show that ADD noise can become a considerable source of underwater noise pollution within
coastal environments, and poses significant risks (e.g., auditory impairment and
displacement) for marine mammals at both individual and population-level scales.
| Date of Award | 25 May 2022 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Sponsors | ESF studentship |
| Supervisor | Ben Wilson (Supervisor) & Denise Risch (Supervisor) |