Updated invasion risk assessment for Ponto-Caspian fishes to the Great Lakes

Majority of invasive species discovered in the Great Lakes since 1985 are native to the Ponto-Caspian region, including species that have had strong negative impacts in the Great Lakes (for example, dreissenid mussels and the round goby). The rich biota of the Ponto-Caspian region coupled with a high volume of commercial shipping traffic strongly suggests that this region will continue to be a major source of invasive species to the Great Lakes. To assess invasion risk by Ponto-Caspian fishes that have not been included in previous studies, we reviewed English-language publications and untranslated European literature (published primarily in Russian), focusing on physiological and ecological traits that have proven useful in previous risk assessments. We then used discriminant analysis to identify fishes that had a high probability of becoming established, spreading, and having significant negative impacts in the Great Lakes. Our updated listing of high-risk Ponto-Caspian fishes includes five species identified previously (the Black and Caspian Sea sprat, Eurasian minnow, big-scale sand smelt, European perch, and monkey goby) and five additional species (the Black sea shad, Caspian tyulka, Volga dwarf goby, Caspian bighead goby, and black-striped pipefish). Of these ten species, four (the monkey goby, big-scale sand smelt, Caspian tyulka, and black-striped pipefish) are likely to survive ballast water exchange as eggs, larvae, or adults based on salinity tolerances. Our results can be used to focus ongoing surveillance and rapid response efforts by highlighting Ponto-Caspian fishes that pose the greatest risk of becoming established and having significant negative impacts in the Great Lakes.