As part of a scheme to monitor the distribution of otters throughout the UK, four Welsh otter survey have been carried out covering the years 1977-78, 1984-85, 1991 and 2002 (funded by the Nature Conservation Council, The Vincent Wildlife Trust - 1984-5 & 1991 - and the Environment Agency respectively). This database is currently only made up of the 1991 and 2002 surveys.
More information on this dataset can be found in the Freshwater Metadatabase - BF_GBIF_26 (http://www.freshwatermetadata.eu/metadb/bf_mdb_view.php?entryID=BF_GBIF_26).