White-clawed Crayfish

The White-clawed Crayfish (Austropotamobius pallipes) is one of our largest freshwater invertebrates, and is the only native crayfish in the UK. They have large claws that are pale on their underside, and it is this distinctive colouring that they are named after. Their carapace (hard layer that covers their back) is generally brown or olive in colour with a pitted appearance.

White-clawed Crayfish are freshwater crustaceans. They live in rivers, streams and lakes. These crayfish tend to hide during the day amongst underwater tree roots, in submerged vegetation and under stones. They can also live in large ponds and canals, and even drainage ditches but they generally prefer areas with clean mineral-rich water and overhanging banks and plants. Crayfish need water that contains minerals to build their carapace, in the same way humans need calcium to grow teeth and nails.

White-clawed Crayfish have important roles in the freshwater environment because of their diet, and their role as a food source for larger animals such as fish, heron and otters. They are also important indicators of good water quality as they are intolerant of pollution.

The White-clawed Crayfish was once a widespread and common species in English and Welsh rivers. However, over past decades they have declined drastically – in the last ten years they have suffered a decline of 50 – 80% across their European range. The White-clawed Crayfish is classified as ‘endangered’ on the IUCN red list of threatened species and are at risk of global extinction.

• Size: 6-12cm
• Life span: 8-12 years
• Diet: Omnivores. Feed on other invertebrates, aquatic plants and dead organic matter.
• Reproduction: Between September and November, the drop in water temperature stimulates White-clawed Crayfish to find mates and reproduce. Females typically have their first young when they are three years old. Female crayfish are very attentive mothers. They carry their eggs for 9 months until they hatch in June. The juvenile crayfish then ‘hitch’ on their mothers back for two weeks before seeking refuges of their own. White-clawed crayfish can live for up to 12 years.
• When to see: White-clawed Crayfish are nocturnal and can be found all year round. They are most active between June and November.
• Population Trend: Declining
• Threats: Invasive non-native crayfish species such as the American Signal Crayfish (Pacifastacus leniusculus), which spread a disease known as the crayfish plague. Habitat damage and water pollution are also significant threats.
• Fun Fact: Whilst most White-clawed Crayfish are brown or olive in colour, other variations have been observed, including blue and red White-claws!

How can you help:

Buglife work with other organisations to give endangered invertebrates such as the White-Clawed Crayfish a brighter future.  Visit our Midlands Crayfish Partnership project page for more information on how you can get involved.

Join a recording scheme and log your finds – download the iRecord app and get recording!

Do remember that we rely on donations to continue our work. If you have searched, found and learnt about our incredible invertebrates on our website, please do consider Making a Donation, Becoming a Member or maybe even making a purchase in our shop.  For more ideas on how to support our work find out how to Get Involved.  Thank you 🕷

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