The Grayling Research Trust

Genetic Assessment of Welsh Dee Grayling Populations

A study of the Welsh Dee population undertaken by Harriet Johnson and her supervisor Martin Taylor at Bangor University has been written up as an M.Sc. thesis. For this study, Rich Cove, Environment Agency, organized a group of anglers to take mouth swabs from 404 grayling caught along 85km of the Dee catchment.

The swabbing technique, routinely applied to humans but not previously tested on other animals apart from bluegill sunfish, was 98% efficient in yielding high-quality DNA. Surprisingly, the genetic analysis revealed no population genetic differentiation within the Dee.

This result could indicate that some substantial weir structures, most notably those around Llangollen, do not prevent upstream movement of grayling in the Dee, although it is also possible that genetic differentiation is present, but not detected by the genetic markers that were available.

If weirs on the Dee are passable by grayling this does not mean that other apparently similar obstacles will necessarily be negotiable on other rivers. All depends on the structure of the potential barriers and in this regard it may be informative to examine the weirs on the Dee in some detail, if indeed they are passable.