The art of trapping

The art of trapping: choosing the right traps
In April 2021, Brussels Environment started using crayfish traps to map the presence of invasive alien crayfish found in Brussels' ponds and waterways. Six crayfish species occur in Belgium, of which only one is indigenous.
To determine which traps provide the best catch results, several crayfish traps were set in different ponds in Brussels where crayfish have been detected. The selected traps will be used during LIFE RIPARIAS surveillance campaign.
While some of the five invasive crayfish species are already present in the project area, others, for which vigilance is needed, are still absent. Indeed, through the LIFE RIPARIAS project, special attention is paid to invasive species that are in the process of being introduced or have recently been observed for the first time in Belgium. An example of such a species is the marble crayfish Procambarus virginalis, which has already been found in the wild in a few places in Belgium, but fortunately has not yet been observed in the LIFE RIPARIAS project area. This invasive species is special because it is the only crayfish in the world that can exclusively reproduce asexually. All individuals in a population are therefore females and the unfertilised eggs they produce will develop into natural genetic clones of their mother. Due to their potential for rapid reproduction, these crayfish pose a great potential threat to indigenous biodiversity. It is therefore important to detect them quickly and take appropriate management measures to prevent their establishment and further spread.