Craywatch unearthed new invasive crayfish
Craywatch, the citizen science project of INBO and the Agency for Nature and Forest, is coming to an end. Between mid-June and mid-October, more than 400 people signed up to map the distribution of alien invasive crayfish. Of these, a total of 220 volunteers laid traps and collected presence and absence data at about 400 locations.
The project yielded striking discoveries. For instance, the number of invasive crayfish species in Flanders was increased by a seventh species: Faxonius virilis. This Union list species was previously observed in one population in the UK (2004) and one in France (2021). In the Netherlands, this species is experiencing a strong expansion. So now an isolated population has also been found in Kortemark (West Flanders). A number of new populations of the marbled crayfish were also discovered, including in the Klein Schietveld and the Stiemerbeek. This is worrying because the asexual reproduction of the latter species favours rapid spread. In addition, we see a further western spread of Procambarus clarkii. This species is now approaching the IJzer valley.
The data and insights gathered will help develop monitoring networks for invasive species, contributing to the protection of vulnerable aquatic systems.
>> More information on the project and the new sightings
Image above: Faxonius virilis (foto: Margot Vermeylen)