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

Despite the growing literature on the topic of freshwater fish invasions, few studies have employed a comprehensive analysis of the stages characterizing the invasion process with reference to the invasion pathway. There is therefore a need to understand more fully invasion pathways to avoid incomplete and biased conclusions and to support adequate management strategies. This study aims to provide a complete analysis of the species traits and invasion history that are associated with the successful passage of an alien freshwater fish species 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, generalized linear mixed models were run, using 23 species traits and seven variables describing introduction history as predictors for 127 established alien freshwater fish species in Europe. The results showed that the release and spread stages were driven primarily by variables related to invasion history (i.e. the type and number of causes of introduction). The establishment stage was driven mainly by functional and ecological traits, while the impact stage was driven both by functional and ecological traits and invasion history. Identifying the main drivers of alien species success at each invasion stage is key to designing stage-specific target management actions and thus contributing to an effective control of alien populations.