2005 Strategic Environmental Assessment SEA7 seabird and marine mammal observations onboard the RSS Charles Darwin during British Geological Survey cruise CD174 in the Rockall Trough

This report was prepared by E Wakefield, British Antarctic Survey as part of the UK Department of Energy and Climate Change's Offshore Energy Strategic Environmental Assessment programme. Observations took place during August - September 2005 on board Charles Darwin. The standard line transect methodology for counting seabirds at sea was used (Webb and Durinck, 1992; Tasker et al. 1984). Observations were made by a single observer from the bridge wings (eye height 14 m above sea level), scanning from directly ahead to either the port or starboard beam. Throughout the cruise a 300 m transect was used for birds on the water. Birds were recorded in five minute blocks and snapshot counts of birds in flight in a 300 x 300 m box were taken at regular intervals. The interval between snapshots was set according to the ship's speed such that counts were made every 300 m along the track (i.e. Counts made every minute when travelling at 10 knots, etc.). An audio alarm was set to sound at the appropriate interval to ensure that snapshots were not missed. Where time and weather conditions allowed behavioural observations were made following Camphuysen and Garthe (2004). Cetaceans were recorded following standard seabirds at sea methods, in the same 90 degree arc as seabirds. In addition however, ranges and bearings to cetaceans were estimated at time of first sighting using an angle board and measuring stick and behavioural observations was recorded following Macleod (2005).

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