Temporal trends in non-native fishes established in the continental United States

Management of non-native fish species is informed by monitoring their temporal and spatial distribution. There are few published analyses of temporal patterns of established non-native fish species. The objective of this study was to examine the utility of the American Fisheries Society’s (AFS) lists of fish names for quantifying trends in the number of established non-native fishes as a first step in determining trends in the number of invasive fish species in the continental United States. As of the 2013 AFS list, there were 66 non-native species listed as established in the continental U.S., a 2.5-fold linear increase from 1970. All of the species, except two, established before 2013 persisted in 2013. The number of species added to each subsequent list increased throughout the period. Eight species were added from 1970 to 1980, 14 from 1980 to 1991, 18 from 1991 to 2004, and 5 from 2004 to 2013. The number of listed non-native families increased linearly from 8 to 19 during the same period. Cichlids, cyprinids, and poeciliids were the most represented families (about 73% of the established species listed in 1970, 1980, and 1991, and about 56% on the 2004 and 2013 lists). Converting the trend in the number of non-native species into the number of invasive species is difficult because of lack of available impact information and the dependency on human perception and value.