The CLANCY project focuses on managing the Chinese mitten crab, an invasive species causing significant problems in waterways around the North Sea. Here is a short update of what our german partner AWI was up to in between October to December 2024.
Recap 2024
The first trap was successful installed in the river “Rohr” in Bremen, Germany.
A short film of the operation can be on our website: interregnorthsea.eu/clancy
Throughout the summer, we continued refining the trap, including improvements such as replacing the large land-based trap boxes with smaller, floating units. No bycatch were found within the season, which confirms how specific these traps are.
The effectiveness of our low-cost trap concept has been further validated through a small project in Bremen, carried out by one of our students as part of his bachelor’s thesis. In this case, we were able to show that the trap concept is effective for catching other crayfish species as well, including the invasive red swamp crayfish.
By the end of October, we had successfully captured 415 red swamp crayfish (see picture), along with 39 mitten crabs and 2 camber crabs.However, some bycatch was observed, including one eel, two rockfish, one frog - all of which were safely released - and a rat. As a consequence of this, we will upgrade the boxes with larger escape hatches.
The crabs we caught were donated to the Botanika in Bremen, where their dwarf otters were excited about the expansion of their diet.
Additionally, we are excited to report that all permits for the three primary traps in the fish ladders at the Bremen Weser weir have now been granted, and construction has begun at AWI. We are optimistic that these traps will be operational by the start of the crab migration in March.
We are now eagerly awaiting the spring migration of the Chinese mitten crab in 2025!
