Studies of harbour seal behaviour in areas of high tidal energy::Part 1. Movements and diving behaviour of harbour seals in Kyle Rhea.

1. This report presents a summary of the data collected during the initial transmitter deployments on harbour seals in the Kyle Rhea study area in 2012. As such it forms one of a series of interim reports describing the movements and diving behaviour of seals in areas of high tidal energy. It is designed simply to present the information most likely to be of use in assessing the potential impacts of any tidal turbine deployments in an easily accessible format. 2. This report summarises the movements and dive behaviour of nine harbour seals caught and tagged at sites within the channel at Kyle Rhea. Seals were fitted with GPS equipped GSM phone tags that provided continuous tracking and dive behaviour data for a total of 506 seal days. 3. Tagged seals concentrated their diving activity within the channel (57% of location fixes) at Kyle Rhea. 4. All of the seals tagged in Kyle Rhea swam repeatedly through the channel in the vicinity of the proposed turbine deployments. We present an example of how seals were distributed in the water column as they passed through one section of the channel. The filtered data shows a clear bimodal pattern in transits with respect to distance from the shore, with transits being less frequent in the central, deeper section of the channel. In addition, there appears to be a reduced density of transits in mid-water through the central deep channel. This would be an expected consequence of the dive profile patterns and has clear and important implications for estimating collision risk. However, the interpolation error due to timing of GPS fixes and the small but significant GPS position error mean that the transit depth and location data will still contain substantial error.