The Firth of Forth once held what may have been the largest native oyster beds in Europe. A century after they vanished, a community led project has returned more than 60,000 oysters to the estuary, doubling its original target.
Stand on the shore at Musselburgh or Leith today and it is hard to imagine what lay beneath the water a couple of centuries ago. The native oyster beds of the Firth of Forth once stretched around 20 miles in length and six miles in width, an area roughly the size of modern Edinburgh. They were arguably the largest in Europe.
Over exploitation and industrial pollution brought that to an end. By the early twentieth century the beds had disappeared. Native oyster reefs are now classed as collapsed under the IUCN Red List of Ecosystems criteria, and the Forth went without native oysters for about a hundred years.
Bringing oysters home
Restoration Forth set out to change that. It is a marine restoration programme working with coastal communities to restore both native oysters and seagrass meadows in the Firth of Forth. Its delivery partners are Heriot-Watt University, Balanced Horizon, Edinburgh Shoreline, Fife Coast & Countryside Trust, the Marine Conservation Society, Project Seagrass, the Scottish Seabird Centre, the Ecology Centre and WWF.
In September 2023 the first native oysters went back into the Forth, the first time the species had been returned to these waters in a century. Màiri McAllan, then Cabinet Secretary for Transport, Net Zero and Just Transition, joined staff, volunteers and partners for the deployment. Caitlin Godfrey of the Marine Conservation Society said at the time: “It’s so exciting that the first native oysters are now in their new home in the Firth of Forth.”
The original funded project aimed to restore 30,000 native oysters and four hectares of seagrass by the end of 2024. The oyster target has since been passed twice over.
Biosecurity first
Moving shellfish around Scotland is not a matter of lifting and dropping. Oysters can carry diseases and other species on their shells. Biosecurity therefore sits at the centre of the project.
For the first deployment, adult oysters were moved from a donor site in Little Loch Broom, on Scotland’s north west coast, to the Forth on the east. Attached plants and animals were screened and removed, the oysters were chemically cleaned, and they were then sorted and counted into clean tanks for five days before release. Later batches of oysters came from the Loch Ryan Oyster Fishery. Every oyster is cleaned before it moves.
That work depends on people. More than 85 people were to be trained in biosecurity and oyster ecology in the first month alone, at Heriot-Watt University and on overnight trips to Ullapool to collect the oysters. Over four years, hundreds of volunteers have helped staff to scrub, check and deploy the shellfish. Kirsty Crawford, Learning and Community Engagement Manager, put it simply: “Local people truly are at the heart of this project.”
Survival and growth
By December 2025 the project had distributed 46,780 oysters at four sites in the Firth of Forth. Monitoring by Heriot-Watt University’s scientific dive team found an average survival rate of around 88 per cent among oysters deployed from boats. One oyster had grown 2.1 centimetres in a single year, roughly double the growth that researchers would expect in good conditions.
Dr Naomi Kennon of Heriot-Watt University said: “These latest results from our monitoring are very exciting.” Caitlin Godfrey added: “We’re thrilled to see such a high survival rate among the oysters in their new home.”
In February and March 2026 volunteers cleaned more than 14,000 further oysters for the spring deployment. In March the project announced that its total had passed 60,000, double the original target. “I’m over the moon to have reached the incredible milestone of 60,000 oysters now back in the Firth of Forth,” said Dr Kennon.
Why native oysters matter
Native oysters do far more than sit on the seabed. Each one can filter up to 200 litres of water a day, improving water quality and clarity. Oyster beds store carbon and create complex structures that shelter a wide range of marine species, including the juvenile fish and invertebrates on which other fisheries depend.
That makes oyster restoration relevant to fisheries managers well beyond the shellfish sector.
Seagrass and communities
Restoration Forth is not only about oysters. Seagrass meadows are another vital coastal habitat that has declined around the UK. During Seagrass Awareness Month in March 2026, the project ran two SeagrassSpotter sessions with Project Seagrass, helping it understand how meadows around the Forth are changing. Members of the public can record their own sightings through the SeagrassSpotter app or website.
The project also wants to understand what the sea means to the people who live beside it. A University of Stirling survey, Blue Communities of the Forth River Basin, asks residents of Edinburgh, Musselburgh, Largo and Anstruther how they value and use the sea. WWF completed an evaluation of the project in 2025, interviewing partners and volunteers about what has been achieved.
Funding and the road ahead
The current phase of the project is funded by Sky and the Cinven Foundation, with support from the Scottish Government’s Nature Restoration Fund, managed by NatureScot. The earlier work was supported by funders including the ScottishPower Foundation, Aviva and the Moondance Foundation.
The oysters will remain in place and continue to be monitored, and further biosecurity training sessions were scheduled at Heriot-Watt University for April 2026. Elsewhere in Scotland, other projects such as the Dornoch Environmental Enhancement Project are carrying out their own oyster restoration, building a wider network of experience.
Nobody pretends the job is finished. “We’re a long way off from the millions of oysters that once thrived in these waters,” Dr Kennon has said. But with 60,000 oysters now back in the Forth, high survival rates and a growing community of trained volunteers, the estuary has its best chance in a century of rebuilding one of its most remarkable habitats.