Modelling the distribution of the pan-continental invasive fish Pseudorasbora parva based on landscape features in the Northern Kyushu Island, Japan

Topmouth gudgeon (Pseudorasbora parva) is widely known as a highly invasive freshwater fish and has expanded from East Asia (native range) to Central Asia, Europe and Northern Africa (introduced range). Although the relationship between the occurrence of P. parva and its habitat conditions remains unclear, information on factors affecting its distribution, especially in its native range, is important for predicting its expansion. This study provides primary information on the distribution of P. parva in rivers and agricultural canals in northern Kyushu Island, Japan, where the fish is native. Fuzzy habitat preference models (FHPMs) and Random Forests (RF) were applied to link landscape features to the distribution of P. parva based on field observation data collected from two distinct ecoregions, the north-western (NW) and north-eastern (NE) parts of Kyushu Island. The results show a clear habitat preference of P. parva for areas with a lower elevation, a gentler slope and a smaller number of river-to-river connections as general landscape features across the ecoregions. Weak preferences are observed for sites with a higher number of river-to-canal connections, a higher canal network index, a larger area of paddy fields, a larger residential area, more crop fields and fewer forests and orchards. Of these site-specific features, five landscape features - elevation, slope, canal network index, area of paddy fields, and presence of forests and orchards - are identified as the most important features for predicting the distribution of P. parva. The general and specific habitat preference information, as demonstrated in this study, may be important in biogeography and invasion ecology. Further research is needed to accumulate information for a better understanding of the invasion ecology and the design of improved management and control strategies against P. parva.