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Description
The goal of our project is the practical verification of the results of applied research in the area of reducing the number of non-native crayfish species in the Czech Republic.
Our activities builds on a TACR project TH02030687 (2017-2020), which resulted in the “Methodology of regulation and eradication of invasive crayfish species: selection of suitable methods depending on the nature of the particular water body“ and the web application „Crayfish in the Czech Republic – a decision support application for the conservation of native fish and crayfish species“.
We will implement the measure on six selected waterways and water reservoirs. Sites with critically endangered species (mostly SAC), which are threatened by the invasion of non-native crayfish, were selected for the implementation of the measures. Eradication of invasive crayfish is a priority here for the management of the object of protection and for the conservation of water biodiversity. At the same time, these are sites of different natural character with different impacts from non-native crayfish species. Therefor a variety of measures and combinations of measures will be practically tested on this selection. For the selected sites, suitable control and eradication interventions and measures against invasive crayfish were selected using the above mentioned web application and will be implemented in accordance with the methodology at the selected sites. The project will therefore be a demonstration example of good practice for the application of the methodology and web application on a wider scale in the Czech Republic.
Dr. Stein Ivar Johnsen from the NINA organization, who is an expert in monitoring the occurrence and eradication of signal crayfish (Pacifastacus leniusculus) in the territory of Norway, will collaborate on the project.
Summary of project results
The aim of our project was the practical application of different methods of controlling invasive crayfish species. We worked on a total of six sites in different types of standing and flowing waters. The spread of populations of non-native invasive crayfish species poses a significant risk to aquatic ecosystems. Invasive crayfish are strong competitors of other organisms. Their high population densities can alter entire aquatic ecosystems. For our native crayfish populations, they represent an even more fundamental danger. They spread ''crayfish plague'', a disease from which our native crayfish are dying.
In the project we used a combination of methods that are known as options for regulating or even eradicating invasive crayfish, but have not yet been applied in the Czech Republic. These included hand crayfish fishing, using of traps, stocking of predatory fish, creation of migration barriers, water level manipulation, and overall pond restoration. Regulatory methods were supplemented by monitoring crayfish abundance and the causative agent of crayfish plague by detecting environmental DNA. We also intensively focused on the most important measure against the spread of invasive crayfish - information sharing among the general and professional public.
In the Zákolanský potok SAC we have created two barriers that prevent the potential migration of invasive spiny-cheek crayfish. In Besének stream we used similar barriers to prevent the spread of the signal crayfish. In the Horní Malše SAC we have fished over 600 signal crayfish out of the river. We stocked 1,120 zander into Kačležský fishpond, which is a good predator of the strong local population of signal crayfish. Over 13,000 signal crayfish were caught in traps and during the fishpond harvest. At Prostřední rybník in Prague, we continued our efforts to eradicate the invasive marbled crayfish and verified the success of the measures by continuous monitoring. At the Stroupínský potok SAC we searched for the source of the crayfish plague and the surviving population of the stone crayfish using traditional methods and eDNA. We educated hundreds of people about the invasive crayfish in face-to-face meetings and informed at least thousands more through the media.
Our project was one of the first attempts to control invasive crayfish that was carried out in the Czech Republic. As far as we know, the modification of migration barriers against the spread of invasive crayfish was used in our project for the first time in the country. In addition to specific interventions against the invasion of non-native crayfish, our project serves as an example for other activities to suppress non-native species and protect our native critically endangered crayfish species.
Summary of bilateral results
The partnership with our Norwegian colleagues has been instrumental in enriching our project, primarily through their wealth of practical experience. In Norway, the conservation of native crayfish is not just an ecological priority; it also serves as a vital economic resource for many communities.A key aspect of our collaboration has been consulting on proposed conservation measures, allowing us to benefit from their expertise. A highlight of this partnership was our recent visit to Norway, where we gained invaluable firsthand insights. Conversely, our Norwegian partners found their trip to the Czech Republic’s project sites equally enlightening.Looking ahead, we are excited to incorporate a stay at NINA into the doctoral studies of one of our project researchers. This opportunity will further strengthen our collaboration. Additionally, we are planning to share strategies for preventing the spread of invasive crayfish and crayfish plague, particularly through the use of temporary barriers in watercourses.A significant challenge ahead for VÚV is the integration of environmental DNA analysis into our routine practices. This innovative method, widely utilized in Norway, is effective in detecting both invasive crayfish and the pathogens responsible for crayfish plague. We look forward to implementing these techniques to enhance our conservation efforts.