Endangered crayfish reintroduced to Swiss rivers

Reintroduction of white-clawed crayfish in Basel-Landschaft Keystone-SDA

Two researchers at the University of Applied Sciences Northwestern Switzerland (FHNW) have bred white-clawed crayfish and reintroduced the highly endangered species to the wild.

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The young crayfish serve as food for fish and other aquatic organisms, Raphael Krieg, who initiated the project with Armin Zenker, told Keystone-ATS. Just after hatching, crayfish are barely a centimetre long. Protected breeding makes it possible to overcome this perilous phase of life.

Egg-bearing females were collected in spring from the Lisselle, a tributary of the Birs, and brought to the FHNW breeding facility. Once the young had hatched, the mothers were returned to the Lisselle.

Protected rearing took place in a facility with specially prepared water and controlled feeding. The aim was to set up a breeding station for white-clawed crayfish in the Birs watershed.

The Lisselle is home to a large population of white-clawed crayfish, making it ideally suited to the project. But two years ago, an unknown event led to the death of many crayfish, explain the researchers.

Reintroduction, they believe, will strengthen this population. Despite its proximity to residential areas, many stretches of the Lisselle provide a good environment for crayfish.

The white-clawed crayfish is one of Switzerland’s four native crayfish species. Considered a bioindicator of water quality, it is under serious threat from habitat destruction, pollution and American crayfish, an invasive species introduced to Europe in the 1970s for culinary reasons.

Translated from German by DeepL/mga

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