Project description and objectives

Commercial scale deployment of marine renewable devices 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 sense is hearing; sound is used for communication, navigation, prey detection and obstacle avoidance.  This research is the initial stage of an investigation into the acoustic interaction 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. Ambient noise data is collected using “Drifting Ears” a method developed by SAMS in conjunction with the European Marine Energy Centre in Orkney.  Autonomous hydrophones record sound continuously whilst drifting with the tidal flow.  Preliminary work suggests heterogeneity in underwater ambient noise and that ambient noise levels are linked to the tidal flow speed and bathymetry.  Further work will include investigations to explain the patterns observed and to assess temporal and geographical variations.  Ultimately, this will lead to a synthesis of results to inform the debate regarding the collision risk to marine mammals from marine renewable devices.

Supervisors

Dr Ben Wilson (Director of Studies), SAMS
Dr Mike Burrows, SAMS

Project funder

• SNH / SEPA

University

• University of the Highlands and Islands