I take it that the question relates to the confirmation of crayfish plague disease in the River Maigue recently.
The White-clawed crayfish is considered a native freshwater species but is very vulnerable to infection by a fungus-like organism Aphanomyces astaci which is microscopic and invisible to the naked eye and is only viable in water. It is completely harmless to people, pets, livestock and all other freshwater organisms. It is however a threat to the White-clawed crayfish, and has decimated crayfish populations in 7 rivers in Ireland since 2015.
The disease is carried by American crayfish species which are now widespread in the UK and Europe but which to date have not been recorded in Ireland. The vector for the disease in Ireland is therefore unknown but is most likely to be transport of spores on fishing gear, recreational craft or equipment used by persons working in or using the rivers for recreation.
My Department is cooperating very closely with the Fish Health Unit in the Marine Institute to investigate all reports of the disease in crayfish and test rivers where crayfish occur. The Institute has the expertise to identify the disease and use DNA testing to determine the particular strain of the disease. We also work closely with the Local Authorities LAWPRO units, Inland Fisheries Ireland, OPW and other relevant bodies.
Our particular focus has been to request all users to observe strict biosecurity and to follow the "Check Clean Dry " protocols which prevent spore transfer.
However the high usage of rivers and "blueways" and the wide range of users, many of whom travel here from overseas, make it enormously difficult to prevent movement of spores.
My Department is considering the possibility of "ark sites" which would be self contained water bodies where all access could be strictly controlled but this consideration is at an early stage.