Site condition monitoring of freshwater pearl mussel in the River Dee 2022–2023

This document contains a summary of the Site Condition Monitoring (SCM) of freshwater pearl mussels in the River Dee from 2022 to 2023. The River Dee is a Special Area of Conservation (SAC) and home to the endangered freshwater pearl mussel. The monitoring survey, conducted by NatureScot and the Cairngorms National Park Authority, found a significant decline, around 90%, in the freshwater pearl mussel population since the last survey in 2002. This decline is largely attributed to Storm Frank in 2015, which caused habitat changes, although other climate change-related factors could also be contributing. The report recommends catchment-wide restoration efforts to address climate change impacts and help recover the freshwater pearl mussel population in the River Dee.