Sea Synergy divers have recorded a rare fan mussel during marine biodiversity surveys in the Portmagee Channel, highlighting the importance of continued research into Kerry's protected coastal habitats.
A rare fan mussel (Atrina fragilis), one of Europe's largest bivalve molluscs, has been discovered in the Portmagee Channel near Valentia Island in Co Kerry.
The discovery was made by divers from Sea Synergy Marine Awareness, Research and Activity Centre and environmental coalition Fair Seas while surveying native European flat oysters within the Portmagee Channel Special Area of Conservation (SAC).
The fan mussel is a threatened species that lives partially buried in soft seabed sediment. Its populations have declined substantially in parts of its range, with the species particularly vulnerable to disturbance from bottom trawling, dredging and pollution.
The Kerry discovery is significant because confirmed records of living fan mussels in Irish waters are uncommon, although the species has previously been documented off Valentia Island and elsewhere around the Irish coast.
Historical records include a sighting near Valentia in 1975 and living specimens recorded off Rathlin Island in Northern Ireland in 1971 and 2007. The Northern Ireland Marine Biodiversity Portal documents historical Irish records, while the Marine Life Information Network also identifies a fan mussel population at Knightstown, Valentia Island.
Fan Mussel Discovery – A large fan mussel, believed to be Atrina fragilis, was recorded during underwater biodiversity surveys in the Portmagee Channel near Valentia Island. Photo: Sea Synergy
Rare Species Found During Oyster Surveys
Elis Martinelli, Marine Programme and Operations Manager at Sea Synergy, said the discovery underlined how little is known about the species.
"We know very little about this mussel. They live in soft sediment with up to two-thirds of their shell buried, they're estimated to live from anywhere between 10 and 100 years.
"They were far more common more than a century ago but they are fragile creatures, vulnerable to trawling, dredging and pollution and have become incredibly rare."
Martinelli described the find as extremely significant, pointing to the scarcity of recent confirmed live sightings.
The species can grow to considerable size and anchors itself to the seabed using fine, silky threads known as byssus.
These fibres have historically attracted interest for their textile properties, while the large shells were once sought after by collectors.
Discovery Highlights Need for Marine Habitat Surveys
Jack O'Donovan Trá, Marine Biologist and Communications Officer with Fair Seas, also participated in the dive.
"The fan mussel is an extraordinarily rare aquatic animal and it's amazing to find it so close to the Kerry coast," he said.
"On the ground projects such as those being run by Sea Synergy and partners are vital because of the lack of detailed marine habitat surveys by government agencies."
He said such research would contribute to a better understanding of threatened marine ecosystems and emphasised the importance of management plans and dedicated surveys of protected marine sites.
The discovery comes as Ireland continues work towards expanding its network of Marine Protected Areas, with Fair Seas campaigning for effective protection of 30% of Irish waters by 2030, including 10% under strict protection.
The campaign forms part of a wider national debate on marine conservation, including Fair Seas' public engagement on Marine Protected Areas and Oireachtas committee discussions on marine protection legislation.
More Than 1,600 Native Oysters Recorded
The fan mussel was encountered during the latest phase of the Sea Synergy Oyster Project, established in collaboration with Portmagee Tidy Towns.
The initiative began following the discovery of an exceptionally large native European flat oyster by local fisherman Brendan Murphy in 2020.
Since then, scientific research, shoreline surveys and snorkelling expeditions have recorded 1,605 living native oysters, including unusually large specimens, and helped map their distribution throughout the Portmagee Channel.
In 2026, the project expanded into deeper waters through SCUBA-based biodiversity and oyster surveys undertaken with Inbhear Sceine Kerry Sub Aqua Club.
The work has received support over the years from the Heritage Council, National Parks and Wildlife Service and Fair Seas.
Fair Seas is a coalition of environmental organisations campaigning for stronger marine protection legislation. Its members include the Irish Wildlife Trust, BirdWatch Ireland, Sustainable Water Network, Irish Whale and Dolphin Group, Streamscapes, Irish Environmental Network and Coastwatch.
The latest discovery adds to the growing body of research on the biodiversity of Kerry's coastal waters and the importance of continued monitoring within designated marine conservation areas.
