Extremely rare and critically endangered giant mussel discovered off Co Kerry coast

The fan mussel, one of the largest and rarest bivalve molluscs in Europe, was discovered near Valentia island by divers from Sea Synergy

An extremely rare and critically endangered giant mussel has been discovered off the coast of Co. Kerry, in what marine conservationists have described as a significant find. Picture: Sea Synergy

An extremely rare and critically endangered giant mussel has been discovered off the coast of Co. Kerry, in what marine conservationists have described as a significant find.

The fan mussel (Atrina fragilis), one of the largest and rarest bivalve molluscs in Europe, was discovered near Valentia island by divers from Sea Synergy Marine Awareness, Research and Activity Centre, and environmental coalition Fair Seas.

The divers were surveying native European flat oyster populations in the Portmagee Channel Special Area of Conservation (SAC) when they came across the threatened species.

They said the discovery is particularly significant because the only other live sightings recorded in Irish waters were off Rathlin Island in Northern Ireland, in 1971 and 2007.

Fan mussel shells have also previously washed up in Cork Harbour and Dingle.

They are estimated to live for between 10 and 100 years but are vulnerable to trawling, dredging and pollution.

Elis Martinelli, marine programme and operations manager with Sea Synergy, said little was known about the species, which lives in soft sediments with up to two-thirds of its shell buried.

“They were far more common more than a century ago, but they are fragile creatures” she said.

“The last sighting in Irish waters was almost 20 years ago off Northern Ireland, so this find is extremely significant.” 

The species was once highly sought after by Victorian shell collectors she added, while its silky threads were used to make luxury items, including gloves and stockings.

Jack O’Donovan Trá, Communications Officer, Fair Seas; Elis Martinelli, Marine Programme and Operations Manager, Sea Synergy; and Lukas Werner, Research Officer, Sea Synergy. Picture: Sea Synergy

Jack O’Donovan Trá, marine biologist and communications officer with Fair Seas, who also took part in the dive, said the discovery highlighted the importance of local marine conservation projects.

“The fan mussel is an extraordinarily rare aquatic animal and it’s amazing to find it so close to the Kerry coast,” he said.

He also stressed that community led projects were particularly important given the lack of detailed marine habitat surveys being carried out by government agencies.

The discovery also underlined the need for management plans and dedicated surveys of Ireland’s protected marine sites, he said, to ensure vulnerable ecosystems could recover and thrive.

The discovery of the rare mussel was made as part of the Sea Synergy Oyster Project which was developed in collaboration with Portmagee Tidy Towns following the discovery of an exceptionally large native oyster by local fisherman Brendan Murphy in 2020.

Since then, scientific research and shoreline and snorkelling surveys have recorded 1,605 living native oysters and helped map their distribution throughout the channel.

This year, the project expanded into deeper waters, with scuba-based biodiversity and oyster surveys carried out in collaboration with Inbhear Sceine Kerry Sub Aqua Club.

The project has received support from the Heritage Council, the National Parks and Wildlife Service (NPWS) and Fair Seas.