Ynys Môn sea trout habitat restoration project

A section of the Afon Gwna in autumn 2014 before the project commenced (2)December 2014

A habitat restoration scheme to improve sea trout spawning potential on an Ynys Môn stream has just been completed thanks to a project carried out by the Trust and Afonydd Cymru involving the Bodorgan Estate and an independent landowner.

The scheme was launched as a result of a survey undertaken by the Trust in 2013 to investigate the Afon Ffraw system that flows from Llyn Coron to the sea at Aberffraw.  The survey concluded that much of the stream and its tributaries were heavily impacted by overgrazing of bankside vegetation by cattle and that sediment had also settled on much of the riverbed smothering the spawning gravels essential for migratory fish.

The restoration project involved the corridor fencing of approximately 850m of riverbank on the Afon Gwna to exclude livestock from the watercourse.  It also included the construction of drinking bays and crossing points in each field with hardcore ramps down to the water’s edge to reduce the amount of silt trodden into the channel as well as upstream and downstream gates to prevent livestock access to the river corridor.

The project also included the selective thinning of overhanging trees to allow re-growth of marginal vegetation and the coppiced material was used to repair eroded bank sections by pinning in brash revetment to create a natural buffer zone to provide a wildlife corridor.

Commenting about the project, Trust chairman, Roger Thomas, said: “The restoration scheme has now addressed these problems.  It is hoped that this work will improve the sea trout spawning potential of the stream from 2015 onwards and the Trust and the Bodorgan Estate will be monitoring the results closely during the next and subsequent spawning seasons”.

The survey in 2013 also concluded that sediment and nutrient runoff from these activities were thought to be contributing factors to the extensive algal blooms that have occurred in Llyn Coron in recent years.  It also identified a number of other areas on the river system that could also be improved by corridor fencing.

The same section of the Afon Gwna in late December after completion of the restoration project (3)