White-clawed Crayfish

White-clawed crayfish is the only crayfish species native to the UK and Ireland. Widespread across England and Wales but rare and elusive due to declining populations. Declines are attributed to the extensive invasion of signal crayfish over the last few decades which carry the disease “crayfish plague” and outcompete native white-clawed crayfish populations. Other contributing factors include loss of habitat and river pollution. Found in freshwater water systems and wetlands. Adults are bronze coloured with pale undersides of the claws.

• Avoid stepping into the water – this can stir up sediment, throwing up sediment DNA and any inhibitory molecules present. Sediment may clog the filter and prevent sufficient volumes of water being filtered.
• It is vital biosecurity is taken into account in survey design to reduce the spread of crayfish plague. Thoroughly disinfect all footwear/waders and equipment before entering the sampling site or moving between sites.