Colonization of the Border Meuse area (The Netherlands and Belgium) by the non-native western tubenose goby Proterorhinus semilunaris (Heckel, 1837) (Teleostei, Gobiidae)

The western tubenose goby, Proterorhinus semilunaris, of Ponto-Caspian origin, already recorded in 2002 from the lowest course of the Dutch River Meuse, was caught upstream for the first time in 2008 in the Border Meuse, the river-stretch forming the border between Belgium and the Netherlands. In 2009 it reached the upstream extremity of the Border Meuse in Wallonia and in 2010 it was recorded in Flanders, in a canal connected to the Border Meuse. Discussion is provided about its migration pathway. Further upstream expansion of the western tubenose goby may be expected in less man-modified and lightly navigated sections of the River Meuse, e. g. those lined with macrophyte-rich habitats. Behavioural competition with the native bullhead Cottus perifretum is likely and might lead to a decline in the bullhead population.