Total numbers of individual fish identified during the Cefas Young Fish Survey (YFS) which ran from 1981 to 2010. The survey deployed a light 2-meter beam trawl to survey inshore locations for small / young fish around the British Isles, predominantly along the south and east coasts. Total numbers of fish (identified to species or if not to the highest taxonomic level) were recorded at each station, and were measured in the majority of cases. The surveys were primarily undertaken to evaluate the abundance of juvenile sole and plaice, as well as providing further information on the abundance of other species of fish. The YFS formed part of the International Young Fish Survey, coordinated by ICES. The survey used commercial inshore vessels to sample with a light 2-meter beam trawl deployed at fixed (prime) stations, towed for a duration of 10-minues, with varying coverage of the British Isles over the time-series period. From 2000 onwards actual shot and haul positions were recorded, whereas prior to this a single generic position was given for a specific prime station. Fish species were nearly always measured, and on the very few occasions that they were not they were counted. These data are currently undergoing quality assurance. Species-specific records for gobies are known to contain taxonomic errors, and analyses should be undertaken on data aggregated to the level of family (Gobiidae). Data for sand smelt Atherina spp. and smelt Osmerus eperlanus may also be confounded, and data for these taxa should be interpreted with particular care.