ac 03 Underwater acoustic interactions between emerging tidal-energy technologies and marine mammals
Caroline Carter (1), Ben Wilson (1), Mike Burrows (1) (1) Scottish Association for Marine Science caroline.carter@sams.ac.uk
Commercial scale deployment of marine renewable devices in European waters is likely to be realised in the near future. However, one potential barrier to the deployment of tidal-stream devices is the perceived collision risk to marine mammals. Marine mammals have excellent sensory perception and underwater agility, but existing collision parallels have shown that marine mammals - though capable - do not always avoid hazards. Marine mammals’ primary underwater long-range sense is hearing. The aim of this presentation is to outline the potential acoustic interactions between emerging tidal-stream devices and marine mammals. Whilst there is much data regarding ambient noise in deep water, there is very little information describing shallow water tidal-stream areas. Also unknown is: how the soundscape may be modified by the tidal devices; and whether the devices will be audible to marine mammals in time to alert them to the devices’ presence. Our underwater sound mapping work suggests considerable heterogeneity in underwater ambient noise and that ambient noise levels are linked to the tidal flow speed and bathymetry. Mapping work conducted in the Sound of Islay, west of Scotland measured broadband sound pressure levels ranging between 81-128 dB re 1 µPa. This leads to results that inform the debate regarding the collision risk to marine mammals from marine renewable devices.