White-Clawed Crayfish Surveys

Background
The white-clawed crayfish is protected under both European and UK law under the Wildlife and Countryside Act 1981 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. In view of this, planning authorities are likely to request a white-clawed crayfish survey is undertaken where rivers and streams are affected by development in areas where the white-clawed crayfish is known to be present. Surveys should be undertaken between July to September and a number of survey methods can be employed.

Survey Methods
The first phase is a presence/absence survey which includes a manual search within the survey area to look for potential refuges. However, this method can only be undertaken where the water depth is no more than 60cm and it is safe to do so.

Trapping
Alternative methods such as trapping may also be used if the standard method is not possible. This involves laying baited mesh traps overnight and any crayfish caught will be released.

Night Viewing
Where the water is too deep to allow a thorough hand search torch searching at night time or trapping will be carried out.

Environmental DNA Survey
eDNA sampling is a highly sensitive non-invasive detection method to monitor crayfish populations. This survey technique can be carried out between 15 April and 30 June. If white clawed crayfish are detected, follow up survey work is often likely to be required, meaning the eDNA survey timing needs to be carefully planned to avoid the risk of needing to carry out further survey the following year.

Report
Following the survey we will provide a detailed report showing our findings and any required mitigation. If required we can develop a suitable mitigation plan for you.