摘要：In recognition of the potential threat posed by introduced species to ecosystem function, the incidence of non-native fishes in rivers and streams of the UK was examined for the years 1961 to 2000 inclusive using data from the Database and Atlas of Freshwater Fishes. The proportion of records pertaining to non-native fishes has remained more or less constant, but the mean number of non-native species was found to be significantly higher in 1991-2000 than in earlier decades, and the proportion of records pertaining to certain species have increased whilst others have decreased.
