DOI: 10.5061/dryad.vt2b3
title: Data from: Harbour seals avoid tidal turbine noise: implications for collision risk

description: 1. Tidal stream energy converters (turbines) are currently being installed
 in tidally energetic coastal sites. However, there is currently a high
 level of uncertainty surrounding the potential environmental impacts on
 marine mammals. This is a key consenting risk to commercial introduction
 of tidal energy technology. Concerns derive primarily from the potential
 for injury to marine mammals through collisions with moving components of
 turbines. To understand the nature of this risk, information on how
 animals respond to tidal turbines is urgently required. 2. We measured the
 behaviour of harbour seals in response to acoustic playbacks of simulated
 tidal turbine sound within a narrow coastal channel subject to strong,
 tidally induced currents. This was carried out using data from
 animal-borne GPS tags and shore-based observations, which were analysed to
 quantify behavioural responses to the turbine sound. 3. Results showed
 that the playback state (silent control or turbine signal) was not a
 significant predictor of the overall number of seals sighted within the
 channel. 4. However, there was a localised impact of the turbine signal;
 tagged harbour seals exhibited significant spatial avoidance of the sound
 which resulted in a reduction in the usage by seals of between 11 and 41%
 at the playback location. The significant decline in usage extended to 500
 m from the playback location at which usage decreased by between 1 and 9%
 during playback. 5. Synthesis and applications: This study provides
 important information for policy makers looking to assess the potential
 impacts of tidal turbines and advise on development of the tidal energy
 industry. Results showing that seals avoid tidal turbine sound suggest
 that a proportion of seals encountering tidal turbines will exhibit
 behavioural responses resulting in avoidance of physical injury; in
 practice, the empirical changes in usage can be used directly as avoidance
 rates when using collision risk models to predict the effects of tidal
 turbines on seals. There is now a clear need to measure how marine mammals
 behave in response to actual operating tidal turbines in the long term to
 learn whether marine mammals and tidal turbines can co-exist safely at the
 scales currently envisaged for the industry.
description: JApEcol_Hastie_etal_observation_data_DryadLand based observer data (.xlsx) used in the analysis of seal responses to tidal turbine sounds. This is effectively counts of seals observed in the water during acoustic playbacks of tidal turbine sound and silent controls. Data were collected by a series of observers located on a clifftop overlooking the study area (Kyle Rhea, Isle of Skye, Scotland) README file is provided as a tab in the file.JApEcol_Hastie_etal_seal_telemetry_data_DryadHarbour seal telemetry data (.xlsx) used in the analysis of changes in usage with distance from the location of playbacks of tidal turbine sound. The data are regularised lat-lon locations from 10 individual harbour seals tagged with GPS telemetry devices. README is provided as a tab in the file.STIMweighted_J11_1hour_withRampSound file (.wav) used during playbacks of simulated tidal turbine sound to harbour seals to investigate avoidance responses. The file has a 10 second ramp at the start and end of the file, and is frequency weighted for use with a J11 underwater speaker.