Increasing number of vimba bream in the Netherlands The numbers of vimba bream (Vimba vimba) are increasing in the Netherlands. The species is native to central and eastern Europe and southern parts of Scandinavia. Vimba breams live in rivers, brackish estuaries and lakes. Semi-anadromous populations of vimba bream are capable of undertaking long distance spawning migrations but also local non-migratory populations occur. In 1989 this exotic species was found in the Dutch part of the Rhine for the first time. Since then numbers have been increasing. Recent catches of fairly large numbers of juvenile vimba bream indicate that the species potentially reproduces in the Netherlands. Especially the high numbers of juveniles caught in the Baakse Beek suggests that spawning might occur there. No actual spawning has been witnessed however. During the first months of 2021, large numbers of subadults (born in 2020) were caught using dipnets at selected locations along the Rhine branches. These likely originate from spawing areas upstream in Germany. Little information is available on the invasiveness of vimba bream. We reach out to the public to keep an eye on spawning vimba bream above gravel beds or in fishladders in the period May-July. De blauwneus is bezig aan een opmars in Nederland. In 1989 werd deze exoot voor het eerst aangetro!en in de Nederrijn. Sindsdien nemen de aantallen toe. Meerdere vangsten van juveniele blauwneus wijzen erop dat de soort zich inmiddels mogelijk ook voortplant in Nederland.