Early January, ProtectFish partner Czech Academy of Sciences launched the local winter sampling campaign on the Svatava River in West Bohemia. Under the guidance of Associate Professor RNDr. Martin Čech, Ph.D., the project team aims to observe cormorants in a selected section of the Svatava River. Wildlife cameras funded by the ProtectFish project are monitoring grey herons, great white egrets, common goosanders, and a significant number of cormorants in the river too.
Winter sampling – what is it?
In cooperation with the Czech Anglers Union, the Czech ProtectFish partner has selected several river stretches where grayling fish stocks are still present, with an existing predation pressure from cormorants.
The selected rivers – two stretches on the Svatava River in West Bohemia and one on the Střela River in the same region – are max. 15 m width in a relatively natural landscape (out of the main urban area) and also naturaly meandering with original tree canopy (mostly alder and willow).
The current 2024-2025 winter sampling campaign serves as a monitoring process to get a better picture about fish-eating predators’ activity on these selected river stretches.
The next experiment in these river stretches (during the 2025/2026 winter) will feature cormorant exclusion – via mechanical barriers such as nets – to analyse whether their absence has an effect on the survival rate of grayling populations.
Winter sampling – goals and objectives
During this winter sampling campaign, the ProtectFish partners intend to assess the actual predation pressure exerted by cormorants and determine if there are any variations between different river stretches. Additionally, it will monitor the impact of other piscivorous predators, such as the grey heron, great white egret, goosander, and common kingfisher.
Winter sampling – the right tools under the best conditions
Our Czech ProtectFish partner installed 3 camera traps on the selected river stretches, 12 cameras in total on both rivers. With these tools, it is possible to monitor the presence of fish-eating predators from dawn to dusk. Night-time fish-eater predators such as the Eurasian otter or mink will not be studied. The reason for only monitoring during sunlight is the quality of pictures and the capacity of SD cards and batteries.
Wildlife cameras are used extensively under the ProtectFish project as tool to count fish predators present by the river (i.e. cormorants) and assess the impact of predation on EU-protected fish such as grayling. Wildlife cameras are also combined with electro-fishing techniques to carry out the counting of predators and prey. In shorter river stretches, the effect of physical structures such as nets and natural structures on fish survival will be studied.
The ProtectFish members are also developing an AI tool to automatically select the most relevant and interesting images captured by the wildlife cameras that have been located on the selected field sites. Currently, team members spend countless hours sifting through thousands of pictures taken by the wildlife cameras, this to identify any significant data for the project. The AI tool aims to significantly reduce this workload, allowing researchers to focus more on analysis and other project activities.
Winter sampling – an important element of research with some risks
As the project is using expensive hardware materials such as wildlife cameras, the project partners take precautions so that the materials are not stolen nor damaged throughout the project’s course. Our biologists tell us that wildlife cameras often get stolen, which unfortunately hampers research results.
More information
website Czech partner: https://www.bc.cas.cz/en/
contact Czech partner: https://www.bc.cas.cz/en/contacts/employee-list/contact/152/
Media contact for any further information – Aliénor: protectfish@alienor.eu