This document offers technical advice providing a standardised protocol for monitoring conservation status on SACs. The survey method is more generally applicable.
This is part of our Good Practice Guidance for Invertebrates, produced by Paul Lee.
Reference: Young MR, Hastie LC & Cooksley SL (2003) Monitoring the Freshwater Pearl Mussel, Margaritifera margaritifera. Conserving Natura 2000 Rivers Monitoring Series No. 2, English Nature, Peterborough.