Rarely spotted so far north, Portuguese men o' war have been washed up in large numbers along the west coast as far north as Donegal over the past week. Southerly gales have swept the marine animals with an extremely dangerous sting ashore west of Clifden's Sky road in the Eyrephort area.
There were also strandings in Kincasslagh, Co Donegal, on Achill island in Co Mayo and in Kilkee, Co Clare, over the past week, proving hazardous to swimmers and surfers.
Connemara fisherman and marine skills instructor Martin O’Malley photographed a number near Eyrephort last Saturday and counted up to 10 in one small pocket. He said it was his first sighting of the animals in this area.
NUI Galway Ryan Institute marine biologist Tom Doyle said it was very unusual to have reports of Portuguese men o' war in such numbers, and to have them this far up the Atlantic seaboard. More frequent storms due to climate change could be a major factor.
Dr Doyle has warned they have an extremely dangerous sting and should not be handled. Medical treatment should be sought immediately if stung, as it could prove fatal. The marine animal was not a jellyfish, technically, but a closely related animal called a siphonophore, he explained.
Resembling a purple-pink balloon with a “Cornish pasty” shape on the surface of the water, the animal trails its tentacles below the sea surface. “Each one washed up on a beach is a colonial animal made up of many different zooids specialised for different functions, as in feeding, reproduction, prey capture.”
There had been only two records in the past century of significant numbers of Portuguese men o' war in these waters, he said – in the mid-1940s and in 1968 off Cape Clear island, Co Cork. About 30 were recorded between Waterford and Cork in August 2012, and there were several individual strandings between 2009 and 2015 in Rush, Co Dublin, and Cork.
“What makes this event unusual is the large numbers washing up since September 12th until now and how widespread the records are, from Cork harbour all the way to Donegal,” Dr Doyle said.