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Sea Synergy Oyster Project


What is the Sea Synergy Oyster Project?
The Sea Synergy Oyster Project (SSOP) was established to study the remaining population of European Native Oysters (Ostrea edulis) and the associated marine biodiversity in the Portmagee Channel, SW Ireland. Through a better understanding of the oysters in the Channel SSOP’s ultimate aim is to undertake an oyster reef restoration project while at the same time raising both locals’ and visitors’ awareness of the significance of both these oysters and the Portmagee Channel in which they live.

Why Ostrea edulis?
O. edulis are filter feeding bivalves. They have two shells, hinged at the base, to protect their soft boneless bodies. To feed they open their shells and pump water across their gills, filtering out microscopic algae and small organic particles from the surrounding water. A single oyster can filter up to a staggering 200 litres of seawater per day!

The larvae of O. edulis like to settle on the surface of live or dead shells in close proximity to adult oysters – preferably on top of them. This results in the formation of complex 3D structures, referred to as oyster reefs, which are very important habitats in their own right for a range of marine species.

O. edulis were once very common in European coastal waters but due to overfishing, disease and the introduction of invasive species its population in UK and Irish waters has declined by 95%. The decline of O. edulis means their reefs are categorised as ‘Critically Endangered’ on the European Habitat Red List.

O. edulis reefs provide many ecosystem services, the most important of which is improved water clarity and quality caused by a substantial population of oysters filtering particles out of the water. This in turn makes photosynthesis easier for algae and plants and improves the health and biodiversity of the surrounding environment.

Reef structures also stabilise the sea bed helping reduce coastal erosion and provide shelter, living space and food for many marine organisms.

Why the Portmagee Channel?
The Portmagee Channel in south-west Kerry is designated a Special Area of Conservation (SAC) because of the important habitats it contains, such as eelgrass and maerl beds, as well as being home to a number of rare, and endemic species. For example, the anemone Edwardsia delapiae (named after Kerry’s very own Maude Delap) is not found anywhere else in the world, and the horseshoe worm (Phoronis psammophila) is found nowhere else in Ireland or Britain. It is also home to a small population of Ostrea edulis which contains some of the largest living oysters recorded in Ireland and the UK with some individuals measuring 178mm in height.

This summer Sea Synergy surveyed a total of nine sites around the Portmagee Channel to:

  • improve our understanding of the distribution and relative density of Ostrea edulis and,
  • establish a baseline of the biodiversity within the channel.

Summary of 2023 


  • 6 locations were identified as having a relatively significant population of native oysters. 
  • A total of 403 oysters were recorded during shore and snorkel based surveys.


  • 54 species from 11 different taxa were recorded during shore based Intertidal surveys.
  • 159 species from 18 different taxa were recorded during Snorkel and Dive Surveys
  • An additional 33 terrestrial species were observed when out on site.
  • Overall an amazing 201 species from 20 different taxa were recorded in our first field season!

Community Engagement

  • Ran 3 workshops in local national schools.
  • Held 3 citizen science seashore recording events.
  • Promoted the project at Discover Derrynane and Cromane SeaFest.

View our full 2023 SSOP Report in PDF format.

Next Steps
For the next field season we plan to continue with baseline surveys of the O. edulis population and the associated biodiversity as well as begin to collect data on the abiotic factors pertinent to oyster survival within the channel. This work will assist us in assessing the feasibility of a native oyster reef restoration project within the channel as well as improving our, and local, understanding and appreciation of the oysters, the habitat they create and the amazing biodiversity of the Portmagee Channel.

Our work this year was made possible thanks to the funding we received from:

  1. National Parks and Wildlife Services (NPWS) Grant for Small Recording Projects 2023. This allowed us to purchase the equipment, field guides and training necessary to conduct surveys within the channel, record and process the data from these surveys and disseminate results to the wider community.
  2. Galway Atlantaquaria Grants for Small Conservation Projects 2023. This enabled us to support a current student of marine biology as an intern offering them an invaluable chance to receive training and get first hand experience in conducting fieldwork, creating reports and engaging with the local community.