Jellyfish which caused mortalities at a fish farm in Inver Bay, Co Donegal, have been identified as string or barbed wire jellyfish.
However, Mowi Ireland, the Norwegian fish farm operator, says that no damage was caused at its site in Inver Bay as it is currently being fallowed.
University College Cork (UCC) expert Dr Tom Doyle says that in the 21 years he had worked with jellyfish he has only ever seen a handful of this species, known as Apolemia uvaria, in a single year.
“To see numbers up there now is very unusual and hasn’t been documented before in Ireland,”he said.
He said he knew of one report in Norway. The string jellyfish is oceanic but not “true jellyfish”, he said.
Warmer sea temperatures with consequent risk of jellyfish and spread of algae, exacerbated by a high level of nutrient run-off from land, has proved challenging for fish farm operators in these waters.
However, Mowi chief operating officer Ben Hadfield told RTÉ Radio 1 Countrywide last Saturday that mortality is substantially down here this year.
“We have seen mortality rates of less than one per cent per month which is low, but during a period in October it rose to three or four per cent,”he said.
Jellyfish damage the gills of fish, and have caused high levels of mortality at fish farms in Ireland and Scotland in past years.
