With two licensed white-clawed crayfish ecologists on the team, agb Environmental provides some detail on why and when crayfish surveys should be undertaken.
Where suitable habitat is identified and crayfish have been recorded in the local area, a crayfish survey will normally be required to validate a planning application.
The white-clawed crayfish is protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended). This is listed under the EC Habitats Directive, a priority species under the Bern Convention and Endangered on the IUCN Red Data List. It is also a UK BAP priority species. Under the WCA, it is illegal to harm, disturb and take white-clawed crayfish without a licence. It is also illegal to buy or sell white-clawed crayfish whether alive or dead. This legislation means that crayfish are of a material consideration within the planning process.
White-clawed crayfish spend most of the day under large stones or in the banks of rivers and lakes. They are generally nocturnal and feed on detritus, animals and plants. Breeding takes place in autumn. The eggs develop whilst attached to the mother’s abdomen, and the female overwinters in burrows with the eggs attached to her. Once the water begins to warm-up again, she will start looking for food. The eggs usually hatch in June. The juveniles remain attached to the mother for about two weeks before becoming independent at the beginning of summer.
The white-clawed crayfish are in decline throughout much Britain and all remaining populations are vulnerable to extinction. The white-clawed crayfish is under threat from a disease known as ‘crayfish plague’ carried by the non-native North American signal crayfish, competition from introduced alien crayfish species, biochemical degradation and mismanagement of their water habitats.
Surveys for white-clawed crayfish are possible between July and October inclusive and several survey methods are available, their use of which will depend on the local conditions. Survey methods include diurnal refuge search, night viewing, bait trapping, and refuge trapping. A Natural England licence is required to survey white-clawed crayfish.
Crayfish-licensed staff at agb Environmental will able to assess the potential for white-clawed crayfish where impacts to watercourses are expected via an Ecological Appraisal. If crayfish presence is considered a reasonable possibility, then we can provide surveys to assess crayfish presence / likely absence. This information can then be used to inform crayfish mitigation for river management and drainage. We are also able to provide crayfish monitoring, rescues and translocations.
Please get in touch with Richard Parmee (Head of Natural Environment) on firstname.lastname@example.org or Cassie Todd (Principal Ecologist) on email@example.com. Alternatively call the our office on 01638 663226 to discuss any projects where crayfish or ecology may be a constraint.