White-Clawed Crayfish

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White-Clawed Crayfish & The Law

White-clawed crayfish are the only native freshwater crayfish species present within the UK. Their claws are creamy or rosy white coloured on the underside, giving them their name. The introduction of invasive non-native species of crayfish has led to the 50-80% decline of white clawed crayfish through direct competition and introduction of the fatal disease crayfish plague carried by introduced species. In addition, habitat loss and water pollution have had further impacts on the native crayfish.

White clawed crayfish are fully protected under the Wildlife and Countryside Act 1981 (amended) and The Conservation of Habitats and Species Regulations (2017). This makes it an offence to kill or injure them as well as disturb them in/or destroy their habitat.

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Typical Habitat

White-clawed crayfish live in rivers and streams (preferably base-rich) throughout the UK. However, due to the presence of invasive crayfish in Britain, their available habitat area has significantly decreased.

Basic requirements for white-clawed crayfish survival include: 

  • Suitable refuges (e.g. stones)
  • Food supply (e.g. leaf litter, macrophytes, aquatic invertebrates, fish remains)
  • Access to other populations for breeding
  • Good water quality
  • No competition from non-native crayfish
  • No crayfish plague (introduced by non-native crayfish)

Crayfish are susceptible to predation (particularly as juveniles and after molting), which makes suitable refuges of utmost importance. Refuges must be fully submerged, sizable enough to cover crayfish, aerated, resistant to high water flows and available for occupation.

Phase II Surveys

A Phase I survey does not require any licences to survey waterbodies. However, if white-clawed crayfish may be present on the site, Phase II surveys may only be undertaken by a trained ecologist with a survey licence for white-clawed crayfish. 

The standard method of surveying for white-clawed crayfish is a manual search of potential refuges within the survey area. However, this method can only be undertaken where the water depth is no more than 60cm and it is safe to do so. Alternative methods such as trapping may also be used if the standard method is not possible but can be more invasive and labour-intensive. Surveys have a limited season and are best undertaken in July to September after they have released their young.

White-Clawed Crayfish and Development

Development that would impact populations and habitats of white-clawed crayfish must have a European Protected Species licence from Natural England and a detailed mitigated and compensation strategy. To meet planning policy, the development will only be allowed if it provides a net benefit to the species. Habitat restoration and modification of features to benefit white-clawed crayfish may be used.

About Protected Species License