Several decades of two invasive fish species (Perccottus glenii, Pseudorasbora parva) of European concern in Lithuanian inland waters; from first appearance to current state

Abstract. Following their first appearance, the invasive fishes Pseudorasbora parva and Perccottus glenii have been in Lithuania for several decades. However, until recently, information relating to their distribution and secondary spread was limited. For this reason, suitable habitats for these fish species were surveyed for their presence across the entire country. Additionally, all previously reported records on the presence of these species were summarized. Results revealed P. glenii to be widely distributed within the country with abundant populations in habitats suitable for the species. The recent distribution of P. parva is restricted to only a few water bodies. It was shown that both species are associated with human mediated transfer, while no natural dispersal of these invasive species was observed. The results of this study suggest that the invasion of Lithuanian inland waters by P. parva and P. glenii is still ongoing, and their occurrence in numerous water bodies, which are still devoid of these species, now seems probable. Demonstrated vectors of P. parva and P. glenii introductions in Lithuania highlight the importance of controlling and screening human activities related to aquaculture, recreational angling and the ornamental fish trade in order to restrict further P. glenii and P. parva expansion in this region.