Species traits and invasion history as predictors of freshwater fish’s invasion success in Europe

Abstract Despite the growing literature on the topic of freshwater fish invasion, few studies employed a comprehensive analysis of the stages characterizing the invasion process (i.e. invasion pathway), thereby demanding a deeper knowledge to avoid incomplete and unbiased conclusions and give support to adequate management strategies. The aim of the present study was to provide a complete analysis of the species traits and invasion history leading an alien freshwater fish species to successfully pass through the invasion pathway stages in European river basins. To predict how likely a freshwater fish species moves from each stage of the invasion pathway - release, establishment, spread and impact - to the next one, Generalized Linear Mixed Models were run, using as predictors 23 functional and ecological species traits, and seven variables describing introduction history for 127 established alien freshwater fish species in Europe. Results showed that the release and spread stages were primarily driven by variables related to the invasion history (i.e. the type and number of causes of introduction). The establishment stage was mainly driven by functional and ecological traits, while the impactstage was driven both by functional and ecological traits and invasion history. By identifying the main drivers of alien species success at a given invasion stage, this study provides scientific knowledge to design target management actions to specific stages of the invasion thus contributing to control their populations more effectively.