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Crayfish Plague Confirmed on Munster Blackwater

7th July 2023
The Blackwater bridge on the Munster Blackwater
The Blackwater bridge on the Munster Blackwater at Fermoy Credit: Andreas F. Borchert via Wikimedia Commons

Water users have been urged to “take precautions” after an outbreak of crayfish plague on the Munster Blackwater catchment.

The National Parks and Wildlife Service (NPWS), Inland Fisheries Ireland (IFI), the Marine Institute and independent ecologists are monitoring what they describe as a “worrying situation”.

Crayfish plague was first discovered in Ireland in 2015 in Co Cavan, and has spread to several other rivers across the country. However, this is the first recorded outbreak of the deadly crayfish plague in Co Cork.

The White-clawed Crayfish is a globally threatened species, and Ireland holds one of the largest surviving populations, the agencies state.

“The crayfish plague is devastating, causing 100% mortality of White-clawed Crayfish. Given the experience of outbreaks elsewhere, a total kill of the crayfish population is expected which will have major consequences for the ecology of the Blackwater, Awbeg and the whole of Munster Blackwater catchment,” they state.

"The crayfish plague is devastating, causing 100% mortality of White-clawed Crayfish"

A National Crayfish Surveillance Programme was established in 2018 as a memorandum of understanding between NPWS and the Marine Institute.

This programme uses environmental DNA (eDNA) a novel, non-invasive method of detection of the DNA of crayfish and the disease from water samples. It monitors the spread and persistence of crayfish plague throughout Ireland and the distribution of the White-clawed Crayfish.

There is no indication as to how crayfish plague reached the catchment but the disease is easily transmitted in water or via contaminated equipment, such as kayaks, waders or nets, they state.

“ It is completely harmless to people, pets, livestock and all other freshwater organisms,”the agencies say, but is of “great concern” as it is within the Blackwater River (Cork/Waterford) Special Area of Conservation (SAC), which contains an internationally important population of White-clawed Crayfish.

The NPWS and IFI are urging all users of any river to implement the “Check, Clean and Dry” protocol, which involves routine checking, cleaning and drying of equipment after leaving a river and before entering another waterbody.

This involves cleaning everything that has been in contact with the water using hot water (above 45oC) or a high-pressure spray if possible, followed by a drying period where all equipment and wet gear is dry for at least 48 hours.

This should be “adopted as standard practice in all freshwaters”, they state, and everything should be disinfected if complete drying is not possible.

Published in Marine Wildlife Team

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Marine Wildlife Around Ireland One of the greatest memories of any day spent boating around the Irish coast is an encounter with marine wildlife.  It's a thrill for young and old to witness seabirds, seals, dolphins and whales right there in their own habitat. As boaters fortunate enough to have experienced it will testify even spotting a distant dorsal fin can be the highlight of any day afloat.  Was that a porpoise? Was it a whale? No matter how brief the glimpse it's a privilege to share the seas with Irish marine wildlife.

Thanks to the location of our beautiful little island, perched in the North Atlantic Ocean there appears to be no shortage of marine life to observe.

From whales to dolphins, seals, sharks and other ocean animals this page documents the most interesting accounts of marine wildlife around our shores. We're keen to receive your observations, your photos, links and youtube clips.

Boaters have a unique perspective and all those who go afloat, from inshore kayaking to offshore yacht racing that what they encounter can be of real value to specialist organisations such as the Irish Whale and Dolphin Group (IWDG) who compile a list of sightings and strandings. The IWDG knowledge base has increased over the past 21 years thanks in part at least to the observations of sailors, anglers, kayakers and boaters.

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