Crayfish plague ruled out in Owel kill investigation

 

Mystery surrounds the death of a large quantity of White-clawed Crayfish at Lough Owel on June 17, after the Marine Institute and the Department of Culture, Heritage and the Gaeltacht (National Parks and Wildlife Service) found the feared Crayfish Plague was not the cause.

 

 

“Dead and living crayfish were collected from the lake by Waterways Ireland staff and taken to the Marine Institute Fish Health Unit for testing. All the tests performed on over 60 individuals have shown that none of the animals had died from or were carrying the Crayfish Plague,” the Department of Culture, Heritage and the Gaeltacht has confirmed this afternoon (Wednesday).

 The Department has admitted that while the kill was not due to Crayfish Plague the reason for it is unclear.

“Unexplained mortalities of the crayfish in Lough Owel have been reported in the past and this could be another such event,” the statement said adding that as only crayfish were involved it would appear not to be due to a pollution event or weather.

“The Department and other agencies will continue to monitor the White-clawed Crayfish population in Lough Owel and research the cause of this event,” the statement concluded.

Lough Owel supports a large and up to now healthy population of the endangered White-clawed Crayfish, the only freshwater crayfish species found in Ireland. 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.

All water users who have been on Lough Owel in recent times are asked to observe the Check, Clean and Dry protocol and thoroughly clean their equipment before using it again. This is especially the case if they are moving to another lake or river.

All wet gear should be checked for any silt or mud, plant material or animals. It then should be cleaned and finally dried.

Lake users are being asked to adopt as standard practice in all fresh waters the habit of using disinfectant or hot water (over 40C) to clean all equipment and then allowing for a 24-hour drying period.

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.

According to the NPWS, 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.