Abundance estimate and acoustic monitoring of Harbour porpoise Phocoena phocoena in the Blasket Islands cSAC

A survey of harbour porpoises (Phocoena phocoena) was carried out within the Blasket Islands candidate Special Area of Conservation (cSAC) to derive density and abundance estimates and carry out static acoustic monitoring. Single platform line-transect surveys were carried out on six days between 16 July and 1 October 2007. Distance sampling was used to derive g(0), which is the density of harbour porpoises on the track of the vessel. Passive acoustic monitoring was carried out through the deployment of self-contained click detectors called T-PODs, which identify and log the echolocation clicks of harbour porpoises. A total of 74 tracks were surveyed of a total distance of 460 km. A total of 44 sightings of 102 individual harbour porpoise were recorded. Sightings of 25 common dolphins (Delphinus delphis), five minke whales (Balaenoptera acutoratrata) and two basking sharks (Cetorhinus maximus) were also recorded.