Notification of Karenia mikimotoi and Noctiluca scintillans blooms; Azaspiracid Shellfish Toxin Event in Southwest & Diarrhetic Shellfish Toxin Event Southeast Offshore Scallops
Diarrhetic Shellfish Toxin Event – Offshore Southeast Coast
Updated 19-09-26
Please note quantifiable levels of Diarrhetic Shellfish Toxin (DST) have been detected in whole tissues of king scallops (Pecten maximus) in non-classified offshore harvesting grounds of the Southeast coast since July 2026.
Whole scallop samples analysed to date during this week (w/c 14-09-26) from ICES rectangle 32 E3 above the recommended toxin limits for DSTs in whole scallops(0.342µg/g)
Fishers of offshore scallops should be aware that there are recent increasing trends in DST concentrations detected in scallops from statistical rectangles to the southeast of Ireland (particularly 33E2, 33E3, 32E2, 32E3, 31E2, 31E3). This elevated trend since July in levels indicates significantly increased risk for DST levels in this species. These elevated results include the detection of a whole scallop sample test result for statistical rectangle 32E2 from the end of August, and a whole scallop sample test result for statistical rectangle 32E3 from this week (w/c 14-09-26) which significantly exceeded the DST whole body recommended limit rendering shucked scallops from these areas ineligible for market. )
For this reason, it is strongly recommended that the scallop super area described by 33E2, 33E3, 32E2, 32E3, 31E2 and 31E3 and adjacent areas should not be fished until further notice due to the increased risk of DST levels exceeding the recommended limit. As always, the rules as described in the Biotoxins Code of Practice, specifically summarised for scallops in the Food Safety Information Notice (both available here), should be consulted should there be any uncertainty regarding appropriate testing processes for offshore scallop fishing.
Noctiluca scintillans declining bloom event – Southwest Coast
Please note cell densities of the bloom forming dinoflagellate Noctiluca scintillans have been observed to be present at low cell densities in multiple inshore locations in the Southwest (Bantry, Dunmanus Kenmare) and South coast (Kinsale) last week (w/c 14-09-26) in samples submitted for the Phytoplankton National Monitoring Program.
While this species is non-toxic, it may cause mortalities among marine organisms, particularly as the bloom decays and depletes oxygen in the water column. It may also cause an unpleasant smell as the bloom breaks down due to the release of ammonia.
It is a naturally occurring bloom which happens annually around the coast of Ireland along South and Southwest coasts, and historically has also been observed off western coasts.
Please report any mortalities and seawater discolouration’s to HABS Team Marine Institute (habs@marine.ie)
Karenia mikimotoi declining bloom event – Southwest Coast
Updated 19-09-26
Analysis of water samples submitted through Phytoplankton National Monitoring and BIM Southwest Mussel Larvae programmes, have revealed cell densities of the bloom forming dinoflagellate Karenia mikimotoi have been significantly decreasing in multiple inshore locations along the South, Southwest, West Southwest coasts over the last 3 weeks. However, low to moderate persistent cell densities are still being observed at the beginning of September in Roaringwater Bay (>109,000 cells/l) and Kinsale (>44,000 cells/l). There have been no observations of water discolouration or mortalities reported during the last 4 weeks.
Please beware previous Karenia mikimotoi blooms in Ireland have also been associated with mortalities of marine organisms including flatfish, benthic invertebrates, as well as farmed shellfish and finfish. It is thought that these mortalities are as a result of depleted or low oxygen levels that can occur when the bloom begins to decay.
Please report any mortalities and seawater discolouration’s to HABS Team Marine Institute (habs@marine.ie)
Azaspiracid Toxin Event – Southwest Coast - Castlemaine, Kenmare, Bantry.
Updated 19-09-26
Low quantifiable concentrations of Azaspiracid Shellfish Toxin (AZA’s) concentrations have been observed in a number of mussel sites in various production areas in Bantry and Dunmanus since mid August, all AZA concentrations are well below the regulatory limit (0.16µg/g). The causative species, Azadinium has been observed in the same areas within Bantry, Kenmare and Dunmanus since mid August.
