A project to open the upper reaches of a Flintshire river to migrating Brown Trout has been a success

A project to open the upper reaches of a Flintshire river to migratory fish has been completed.

An old weir that had previously been the upper limit for migrating fish on the River Terrig has Plas Nant y Glyn, Nercwys has now been removed by Natural Resources Wales.

The work has opened up around 4km of habitat and spawning ground in a river that is known for its Brown Trout population.

Hours after the work had been completed Brown Trout were seen successfully leaping the lowered weir and heading upstream.

Richard Pierce, Fisheries Technical Officer at Natural Resources Wales, said:

“The Terrig is an important nursery tributary which supplies the River Alyn with Brown Trout

“The barrier removal work on the Terrig, which is the largest tributary of the Alyn, involved lowering the weir in stepped increments and raising the pool level below to make the water more passable to migrating fish.”

“Within hours of the work’s completion, Brown Trout were seen successfully leaping the lowered weir and heading upstream to new habitats and spawning grounds.”

Man-made structures in rivers not only impact on fish migration but can interrupt gravel movement and fragment whole river catchments.”

“Upper reaches of river catchments tend to be cooler and protected to a certain extent, from the worst effects of climate change, so their removal effectively future proofs the river and its ecology.”

The work started in early October and took just a week to complete, Natural Rescources Wales says it is part of “ongoing work to explore more river restoration opportunities.”