River Severn to River Thames Transfer (STT) Strategic Resource Option (SRO). River Vyrnwy Salmonid Glochidia Assessment Report

Description of Activity

This report is part of series of Environmental Assessment Reports which catalogue the set of environmental assessments of the River Severn to River Thames Transfer (STT) Strategic Resource Option (SRO).

Following discussions with Natural Resources Wales, it was determined that an investigation into the potential for freshwater pearl mussels within one of the reaches of interest needed to be completed.

The freshwater pearl mussel (Margaritifera margaritifera) is an endangered bivalve mollusc species, with presence of mussel populations traditionally assessed for using techniques including diving, aquascope, and more recently environmental DNA (eDNA). The glochidia (larvae) of M. margaritifera parasitise the gills of salmonids, and therefore electrofishing and live inspection of the captured fishes’ gills via the naked eye provides non-destructive and cost-effective opportunities to assess the presence and abundance of the species within watercourses. This report is an overview of the evidence gathered during the Salmonid Glochidia Assessment surveys conducted on the River Vyrnwy.

Period	2023 → …
Work for	Ricardo, United Kingdom
Degree of Recognition	National