Original provider: National Parks and Wildlife Service, Dept. of Environment, Heritage and Local Government Dataset credits: National Parks and Wildlife Service, Dept. of Environment, Heritage and Local Government Michelle Cronin, Coastal & Marine Resources Centre, University College Cork Abstract: The status of Ireland's harbor seal Phoca vitulina vitulina population is poorly understood. The most recent national population estimate dates back to the breeding season in 1978 and did not cover the entire coastline. Reliable up-to-date information on the abundance and distribution of harbor seals in Ireland is necessary to assess the conservation status of the species and for the effective identification, management and monitoring of special areas of conservation required for harbor seals under the European Union Habitats Directive. To provide comprehensive current information on Ireland's harbor seal population, a geographically extensive survey was conducted along the coastline of the Republic of Ireland during the species' annual moult in August 2003. This complemented a similar survey of Northern Ireland, which was conducted in 2002. Using thermal imaging technology, haul-out groups of harbor seals and grey seals Halichoerus grypus were identified from the air, aerial-counts were obtained and compared with simultaneous ground-count data from selected sites. Harbor seal distribution recorded during the 2003 moult season was concentrated in the south-west, west and north-west of the country. This national survey yielded a minimum population estimate for the Republic of Ireland of 2905 harbor seals, delivering an effective baseline for current and future population research. Supplemental information: This dataset also includes ancillary grey seal data, showing summer terrestrial distribution of grey seals. This data cannot be used for estimating population size of grey seals as this is conducted during the winter breeding season.