The white-clawed crayfish Austropotamobius pallipes is the UK’s only native crayfish species and is fully protected due to severe declines caused by habitat loss, pollution, and the invasive signal crayfish and its associated crayfish plague. Any works affecting rivers, streams, canals, lakes, ponds, or associated riparian zones must carefully consider their potential presence. At Wold Ecology, we undertake precise, legally compliant surveys to support development while ensuring the conservation of this vulnerable species.
All survey methods follow Natural England, Environment Agency, and CIEEM best-practice guidance, ensuring high-quality, defensible results.
1. Desk Study & Habitat Assessment
We begin by reviewing local records, historic data, and watercourse characteristics. During a habitat walkover, our ecologists assess:
Flow conditions and water quality
Substrate type (cobble, boulder, gravel)
refuges such as undercut banks, stone crevices, and submerged roots
Connectivity to known populations
This identifies whether a full survey is needed.
2. Manual Hand Searching
In clear, shallow water, we carefully inspect suitable refuges along the riverbed and banks.
Stones and debris are lifted selectively and replaced immediately.
Findings include presence, size classes, and relative abundance.
3. Night-Time Torch Surveys
Crayfish are often more active at night. Using high-powered torches, we survey watercourses to identify individuals feeding or moving across the substrate.
4. Trapping (Where Licensed & Appropriate)
Under strict licensing requirements, low-impact traps may be deployed to confirm presence or estimate population structure.
Only approved, biosecure equipment is used.
Measures are taken to prevent bycatch and disturbance.
5. Biosecurity Protocols
Given the risk of spreading crayfish plague, all surveys are conducted under stringent biosecurity procedures, including disinfection of equipment and clothing.
6. Reporting, Licensing & Mitigation
Our reports provide clear findings, risk assessments, and recommendations regarding:
Avoidance of impacts on native crayfish
Construction timing and watercourse protection
Pollution prevention and runoff control
Licensing requirements where harm or disturbance is unavoidable
Sensitive design and early ecological consideration can ensure development progresses without harming native crayfish populations. Wold Ecology works closely with clients to deliver proportionate, practical solutions.
Common mitigation and integration measures include:
Maintaining and enhancing natural riverbed structure
Retaining key refuges such as submerged roots, cobble beds, and undercut banks
Implementing strict pollution prevention measures during construction
Using sediment control barriers and careful timing of in-channel works
Avoiding or minimising in-stream disturbance, especially during sensitive periods
Creating new refuges such as stone clusters, woody debris, or artificial crayfish shelters
Applying robust biosecurity measures to prevent the spread of invasive species or disease
Our aim is to facilitate sustainable development that fully respects the ecological importance of native crayfish populations while keeping projects on track.