News Icon

News

« Return to News

13 January 2015

Hedgehogs to help Crucian Carp at Trevalyn, North Wales

Putting ‘hedgehogs’ in a lake might seem like a cruel fate for one of our beloved mammals but on this occasion the ‘hedgehogs’ are spiked plastic systems used to provide cover for fish.

Pete Worrall and Ryan (from Wright Landscapes) rowing out the first hedgehog.

Three years ago we worked with Chris Burnett Associates (Landscape Architects) to restore a natural landscape to an intensely cultivated corner of North Wales. This involved the creation of lakes, marshes, woodland and meadows which together have demonstrated that managed form in the landscape can be achieved alongside significant ecological value.

Although we had initially decided on self-colonisation for fish in the one hectare lake, an opportunity arose to establish the water body as an Ark site for one of the UK’s threatened fish species, the Crucian Carp (Carassius carassious). This native species has been in decline in the UK largely due to hybridization with introduced species including Koi carp, together with the loss of farm ponds and the intensive management of our rivers. The lake is not subject to flooding from the local river system so the risk of contamination with other carp species is limited, and the site has a management plan that prohibits the release of other carp species.

Deploying the weighted hedgehogs was not without risks of sinking the boat! (Note the novel float used to identify the location of the submerged hedgehog).

Although the lake has a well developed fringing reedbed and other submerged and emergent aquatic plants it was decided to add additional protection from fish predation by installing the ‘Hedgehog’ systems. These were placed in the lake to form two separate reefs which it is hoped the fish will use as cover from the recently arrived cormorants (Phalacrocorax carbo). The only other fish species introduced at the same time as the Crucian carp were Rudd (Scardinius erythrophalamus), a shoaling fish that will make use of the extensive reed margin to the lake.

PAA offer a full range of consultant expertise relating to habitat restoration and rare/protected species – please contact us for more information, or feel free to download one of our relevant fliers below:

Animals- Protected Species and Development
Aquatic Invertebrates and Biological Water Quality Monitoring
Habitat Creation & Restoration
Wetlands – Sustainable Urban Drainage
Working in Wales