Crayfish plague and an invasive species


Sir, – Kevin O’Sullivan’s article “Outbreak in Tipperary has caused death of endangered white-clawed crayfish species” (August 28th) underlines that we have a serious ecological and legal problem, but is the Minister taking note? Incidentally, the accompanying photograph shows the invasive American red swamp crayfish, not the endangered white-clawed crayfish.

These large and long-lived invertebrates, key to lake and stream ecology, are under extreme threat in Europe. About 30 years ago, my research team detected and identified the first crayfish plague outbreak in Ireland, which eradicated stocks from the eastern Shannon catchment and the Boyne. For many years, I promoted European publicity and public education on crayfish, but with indifferent success in Ireland. Now, inside two years, we have four new outbreaks, from Cavan to Limerick, Waterford and Tipperary. But what is quite unusual in Europe is that no alien crayfish disease-carriers have so far been detected in any Irish case. This should allow a chance to let stocks recover, while in the presence of American crayfish they will be hit again and again by the disease, as has happened in England, France, Spain, etc. But a new study has found American crayfish for sale here online, and if these are released (as happens commonly across Europe), the genie is truly out of the bottle.

White-clawed crayfish have been protected for many years by EU legislation, but we have also known for many years that our national legislation is deficient, so officials feel constrained against prosecuting those importing or selling alien crayfish. Why does the Government not act? Does our aquatic environment mean so little to them, or the prospect of yet another European fine? – Yours, etc,


(Emeritus Fellow TCD),


Co Dublin.