eDNA testing Confirms Arctic Charr Spawning in afon Fachwen

Arctic Charr (Salvelinus alpinus) are remarkable fish that thrive in the cold, clear waters of Llyn Padarn. However, like many species, their spawning behaviors are vulnerable to environmental changes. While Afon y Bala is a well-documented spawning site, the role of other tributaries has remained unclear.

The Study

To uncover potential new spawning sites, our team used environmental DNA (eDNA), a cutting-edge, non-invasive method. Water samples were taken from five tributaries of Llyn Padarn: Afon Hwch, Nant Peris, Afon y Bala, Afon Fachwen, and Afon Goch. Filters were used to capture DNA from the water, which was then analysed to determine the presence of Arctic Charr.

Sampling began on November 6, outside the known spawning window, to establish a baseline. No Charr DNA was detected, confirming that these fish do not linger in the tributaries year-round. Subsequent sampling during the spawning season, on December 10 and December 19, revealed fascinating results.

Key Findings

On December 10, positive eDNA signals confirmed the presence of Arctic Charr in Afon y Bala, reinforcing its status as a primary spawning site. However, the December 19 tests revealed something new: for the first time, Charr DNA was detected in Afon Fachwen during the spawning season.

While this doesn’t definitively prove spawning activity in Afon Fachwen, the presence of Charr during this critical period strongly suggests it is a spawning site. This finding highlights the need for further investigation and conservation efforts in this tributary.

In contrast, no Charr DNA was detected in Afon Hwch or Nant Peris. Barriers such as weirs may be limiting access to suitable upstream habitats, underscoring the importance of assessing and managing these obstructions.

Why It Matters

The confirmation of Arctic Charr activity in Afon Fachwen is a significant step forward for their conservation in Llyn Padarn. Understanding where Charr spawn allows us to prioritise habitat restoration and ensure access to these critical areas.

The use of eDNA in this study proved invaluable. By filtering just a few litres of water, we were able to pinpoint Charr activity without disturbing their habitat. This innovative approach provides a powerful tool for monitoring sensitive species in remote or challenging environments.

Next Steps

These findings open new avenues for conservation in Llyn Padarn. By focusing on habitats like Afon Fachwen and addressing barriers in other tributaries, we can help safeguard the future of Arctic Charr in this unique ecosystem.

With tools like eDNA, we’re uncovering the secrets of the Charr and ensuring their story continues for generations to come.