Native fish introduced to control populations of invasive species

Natural Resources Wales (NRW) has introduced a native fish species to several locations to control invasive populations of Topmouth gudgeon..

The introductions of European perch have taken place at five sites in Camarthenshire at Sandy Water Park, Morolwg, Ashpits and Lower Lliedi reservoir in Llanelli, and a private pond in Cynheidre.

Their introduction follows extensive research into predator-prey relationships.

Perch, a native species, has been identified as a natural predator of Topmouth gudgeon and provide an effective method of population control without the need for chemical intervention.

Topmouth gudgeon is listed under the retained EU Invasive Alien Species Regulation 2014 and is a GB rapid response priority species.

Ecological consequences

Its presence threatens native wildlife and habitats, and its rapid spread could have serious ecological consequences.

Beth Greenfield, Specialist Advisor for Invasive Non-native Species (Inns) management, NRW, said: “By introducing a natural predator, we are taking a proactive and sustainable approach to managing invasive fish populations while supporting native biodiversity.”

“While chemical treatment is the most effective method for managing Topmouth gudgeon in the UK, these particular sites have been evaluated and found unsuitable due to their size and connectivity with other water bodies. In these circumstances, the use of perch offers a viable alternative to managing the invasive fish population.

“This initiative is based on rigorous scientific research, and our team will closely monitor the effectiveness of the approach through regular surveys and advanced molecular analysis techniques.

Increased activity

Local anglers and residents may notice increased activity around these water bodies, including the presence of NRW teams conducting fish introductions, setting up monitoring equipment, and performing regular ecological surveys.

The introduction of perch has been funded by the Welsh Government and the programme has been developed by NRW working closely with Carmarthenshire County Council, Llanelli Rural Council, Swiss Valley Angling Association, and a private landowner.

For more information or to report sightings of invasive fish species, please contact 0300 065 3000 or visit NRW’s website.