A GIS based quantification of Ireland's freshwater salmon habitat asset to determine the habitat quantity (wetted river and lake surface areas) available to migratory salmonids.  The purpose was to inform the further development of salmon stock recruitment models to provide high quality scientific advice to inform the sustainable management of salmon fisheries in Ireland. The identification of these rivers as Salmon, Sea Trout or other types of systems is still valid and has not changed since the 2003 report was published. It should be noted that rivers identified in 2003 as ‘Not considered a significant producer of migratory Salmonids’ or river segments identified as ‘Not utilised by Salmon’ may hold small populations of salmon and/or sea trout which are important in biodiversity terms.Please note that the wetted areas (riverine habitat (m²)) were revised in 2012 (McGinnity et al., 2012). This work built on the 2003 wetted area report (Mc Ginnity et al., 2003).McGinnity, P.,Gargan, P.,Roche, W., Mills, P. & McGarrigle, M. 2003. Quantification of the Freshwater Salmon Habitat Asset in Ireland using data interpreted in a GIS platform. Irish Freshwater Fisheries, Ecology and Management Series: Number 3, Central Fisheries Board, Dublin, Ireland.McGinnity, P. et al., 2012. A predictive model for estimating river habitat area using GIS-derived catchment and river variables. Fisheries Management and Ecology. 19. 69-77.