Potential range of the invasive fish rotan (Perccottus glenii) in the Holarctic

Rotan Perccottus glenii is one of the most widespread alien invasive freshwater fish in Eurasia. We reviewed the mechanisms of its dispersion, identified the potential range and regarded these results in the light of possible prevention of further expansion. Our analysis was based on 970 presence records and 198 absence records from both invaded and native parts of the range. Since 1916 invasion dynamics of rotan have been driven by episodic anthropogenic translocations, followed by spontaneous expansion within river networks, and secondary translocations. Maxent species distribution models with independent validations showed that rotan distribution in Eurasia has climatic limitations; rotan have already invaded most areas with high climatic suitability in the Palearctic, but some regions of North Eurasia and North America, where rotan is currently absent, have high climatic suitability and may be vulnerable to invasion in the future. Rotan's high invasiveness, lack of geographical barriers and absence of reliable methods to prevent spread present a very high risk of expansion within appropriate climate limits in Europe. Our analysis shows that the long-term invasion dynamics of an invasive freshwater species may depend on climate variables rather than on river basin borders. Species distribution models, based on large scale environmental layers, can be useful to understand the invasion risk for other freshwater species restricted to shallow aquatic habitats.