White-Clawed Crayfish Surveys

The white-clawed crayfish is Britain's only native species of crayfish and is primarily under threat from non-native species including the North American signal crayfish that carry a fungal disease known as 'crayfish plague'. Crayfish will occupy a variety of habitats including streams, rivers, brooks, reservoirs and water-filled quarries. Although abundant in some waterbodies, the white-clawed crayfish has seen a dramatic decline in population in recent decades. This decline has led to the white-clawed crayfish being protected under both British and European law. The white-clawed crayfish is listed on Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) and is also included in Appendix III of the Bern Convention and Annexes II and V of the European Habitats and Species Directive. It is also a Priority Species under the UK Biodiversity Action Plan (BAP).

Therefore, if development works are planned to be completed within, or in close proximity to a suitable waterbody, it is important to determine if white-clawed crayfish are present and whether the proposed works will impact on the species.

EMEC Ecology work with many different clients from Local Authorities to private developers. Each survey will be tailored to a specific site and the costs will change accordingly. EMEC Ecology is happy to provide a quotation for any white clawed crayfish survey that will be both efficient and cost effective to the site specifics. Reports are produced as soon as possible, however should you have a specific date for submission with a planning application we will do our utmost to accommodate this.

If you require a quotation please send an email to us at mail@emec-ecology.co.uk including any site plans that you have available (or details and photographs of the site if applicable) with details of the proposed works, along with your contact details. Should you wish to contact us at the office please call 0115 964 4828.

White-Clawed Crayfish Survey Methodology

Often the local biological record centre may be contacted to see if there are records of crayfish within the waterbody that the works will potentially impact on. Desk studies assist the findings of the survey and would be included within the report that is submitted with a planning application. A desk study is not always required however, and will be dependant on the site and its location.

Even when there are records of white-clawed crayfish in a watercourse, they are not uniformly spread along the channel and therefore a survey of crayfish presence and population must be conducted on site. All surveys are conducted by a suitably qualified ecologist with an appropriate Natural England crayfish licence.

Refuge Sampling

The standard method used to search for crayfish along a watercourse includes taking samples from potential refuges and completing a habitat assessment. Several samples may be required to be able to establish a population estimate (although normally the primary purpose of the survey is to establish presence or presumed absence). Where appropriate, kick sampling using a pond net is also used.

Night Viewing

This method involves recording crayfish via torchlight at night. This method results in minimal disturbance to the watercourse, covers a wider area and also covers inaccessible areas compared to manual searches such as refuge sampling.

Crayfish Trapping

A successful method uses baited traps that are left in situ for no longer than 24 hours at a time. Traps are set in the evening and then retrieved the following morning and any captured white-clawed crayfish are released. This method requires consent from the Environment Agency. Only 'otter friendly' traps are used.

Survey Times

White-clawed crayfish surveys can be carried out between July and September inclusively. Surveying between April and June (other than torching at night) is not advised as it is likely to cause harm to the juvenile crayfish.

A summary of this information is also available as a PDf document. White-clawed Crayfish Survey - Information Sheet.

White-Clawed Crayfish Licensing and Mitigation

Should white-clawed crayfish be present within or in close proximity to a development site, where it is likely that the crayfish will be either disturbed, injured or killed by the proposed works, it may be necessary to translocate the crayfish i.e. (move them to another location). This will require a conservation licence from Natural England that will require detailed mitigation, compensation and enhancement to ensure no adverse impacts on this declining species.

Should a licence be required, EMEC Ecology can apply for this on a client's behalf. EMEC Ecology has the ability to design and implement site-specific mitigation, compensation and enhancement that will be suitable for a planning application.

Mitigation by Translocation

Translocation involves moving the white-clawed crayfish from the area to be affected into safe areas of suitable habitat to avoid any negative impacts form the development works. This will require the identification of a suitable receptor site. Should a suitable site not be identified, EMEC Ecology can assist in the design and creation of suitable habitat. This process will ensure that both habitat management and enhancement have been considered, a pre-requisite of planning applications.


Monitoring the impact of development works is an important part of conservation and should it be required (it is often a stipulation of a licence), EMEC Ecology can monitor the site to see how effective the mitigation has been.

White-Clawed Crayfish Projects (Surveys and Mitigation)

White-clawed Crayfish Survey near Nottingham

Initial survey work revealed the presence of a healthy population of native crayfish and no invasive crayfish species. As these were located where development works would affect them EMEC Ecology took part in the production of a mitigation strategy, under a conservation licence from Natural England, of this site near Nottingham. Over one hundred white-clawed crayfish were excluded from a target area and translocated to a suitable receptor site prior to the development works. While high risk elements of the works were carried out EMEC Ecology worked closely with the contractors as Ecological Clerk of Works. In conjunction with the translocation of white-clawed crayfish mitigation, this project involved the creation and enhancement of suitable crayfish habitat. EMEC Ecology will carry out monitoring over the next two years to determine the success of the scheme.