Catchment News

Crayfish Plague spreads to River Barrow – water users are urged to follow biosecurity advice to contain outbreak

Large numbers of dead freshwater crayfish were reported in the River Barrow in the stretch from Carlow to Graiguemanagh. It has been confirmed using DNA analysis that the cause of death was Crayfish Plague. This is the fifth outbreak of the disease to be found in Ireland in the last two years. It is feared that if the disease spreads further, then it will threaten the survival of the entire Irish population of this endangered species.

This worrying situation is being investigated by the National Parks and Wildlife Service (NPWS) of the Department of Culture, Heritage and the Gaeltacht, Inland Fisheries Ireland (IFI) and the Marine Institute.

The kill only impacts White-clawed Crayfish; other freshwater animals and people are not affected. Experience of the disease elsewhere is that it causes 100% mortality. It is of grave concern that if the disease takes a firm hold millions of crayfish could vanish from Irish rivers and lakes in a short period of time.

All the agencies involved in managing and protecting the rivers in Ireland are concerned that another outbreak has been detected and are reiterating their advice and guidance to all users of the river to implement routine cleaning and drying of their equipment once they leave the river and before using it again. This is especially important as it is known that the crayfish plague organism can be carried on wet equipment to new sites. Containment of the outbreak is essential to prevent spread to other as yet unaffected populations in Ireland.

Temporary ban on moving any equipment into or out of the Barrow

Waterways Ireland who manage the Barrow navigation have issued a marine notice calling all recreational, commercial, private and public body water users (boaters, walkers, swimmers, kayakers, rowers, machine operators, etc.) to operate a temporary ban on moving water sports/angling equipment and other equipment/machinery that comes in contact with the water, out of, or into the Barrow and all affected catchments.

Please Clean, Check and Dry

Anyone using the river is being urged to observe the Check, Clean and Dry protocol.

• All wet gear should be checked for any silt or mud, plant material or animals.
• It then should be cleaned and finally dried.
• Disinfectant or hot water (over 60C) should be used to clean all equipment followed by a 24hr drying period should be adopted as standard practice in all freshwaters.
• Drying is especially important, including removing of any water from inside a boat and disposing of it on grass. A drying period of at least 24 hours is needed to ensure that a boat is clear of infectious organism.

Please report any sightings of dead or unusual Crayfish

People are also asked to alert the authorities of any mass mortality of crayfish or sightings of unusual crayfish that might be non-native species (e.g. crayfish with red claws, large size).

The White-clawed Crayfish is a globally threatened species and Ireland holds one of the largest surviving populations. It is the only freshwater crayfish species found in Ireland and is present in lakes, rivers and streams over much of the island. Throughout its European range, this species has been decimated by the impact of Crayfish Plague which spread to Europe with the introduction of North American species of crayfish. Until 2015, Ireland was considered free of the disease and it remains the only European country without any established non-native crayfish species.

Many American crayfish species are resistant to Crayfish Plague, but can act as carriers of the disease which is rapidly fatal when passed to the White-clawed Crayfish. The combined impact of the introduced crayfish species (which may out-compete the smaller native crayfish) and Crayfish Plague have completely eliminated the White-clawed Crayfish from much of its European range, leaving Ireland as the last stronghold of the species. The species is protected under Irish Law and the EU Habitats Directive. It is illegal to deliberately release any non-native species of crayfish into Irish freshwaters.

If Crayfish Plague becomes established there is a high probability that the White-clawed Crayfish will be eliminated from much of the island. Furthermore, if non-native crayfish are found to be established in Ireland, this could have a severe impact on habitats (e.g. destabilising canal and river banks by burrowing) and other freshwater species, such as salmon and trout fisheries. However there is no evidence to date that non-native freshwater crayfish have been introduced to Ireland.

Who to contact

For further information contact Brian Nelson on 01 8883294; brian.nelson@chg.gov.ie or

Ciaran O’Keeffe – 087 2646416 ciaran.okeeffe@chg.gov.ie)

Anyone who sees any dead or dying crayfish should report this in the first instance to either the Marine Institute (Deborah Cheslett Deborah.Cheslett@marine.ie) or National Parks and Wildlife Service (Brian Nelson or the local ranger).

Members of the public who suspect they have seen a non-native species of crayfish are asked to take a picture of it showing the underside of the claws and submit this through this web page http://invasivespeciesireland.com/alien-watch/ or direct to Colette Flynn email: coflynn@biodiversityireland.ie Phone: 051 306248