Establishing the sensitivity of cetaceans and seals to acoustic deterrent devices in Scotland

The aim of the project is to provide the capability to establish potential risks to cetaceans and seals from the use of acoustic deterrent devices in Scottish waters. Acoustic Deterrent Devices (ADDs) are often used on aquaculture sites to reduce predation of seals on fish stocks using acoustic emissions. These acoustic emissions may also have secondary effects on marine mammals (including non-target species) ranging from physical injury, behavioural response and reduced sensory capability. In this project, an attempt is made to investigate the effects of water depth, seabed sediment type and bathymetry on the propagation and received levels of ADDs. It also examines the implications of simplified modelling approaches and associated prediction of a ‘zone of potential risk’. A generalised sensitivity model has been developed to allow prediction of the range to exceed predetermined thresholds (e.g. for hearing injury) based on sound pressure levels and cumulative sound exposure levels for user defined impact criteria based on ADD type, local environments and functional hearing capabilities of species present in Scotland.