Native oyster nursery aims to save species from extinction

Hundreds of native oysters have returned to Belfast Lough as part of efforts to bring the 'ocean superheroes' back from the brink of extinction. 

Join us today and together we can BRING NATURE BACK

The ambitious restoration project, officially launched today by Ulster Wildlife to mark Endangered Species Day, sees approximately 700 mature oysters (Ostrea edulis) suspended in cages under the pontoons of Bangor Marina, creating the first native oyster nursery of its kind on the island of Ireland.

As sea temperatures warm over the coming months, the 24 nursery cages will generate millions of oyster larvae which will settle on the seabed, helping the native oyster population recover while also boosting biodiversity and improving water quality in Belfast Lough.

A single oyster can filter up to 200 litres of seawater, equivalent to a bathtub, per day, significantly improving water quality and reducing pollution levels. The larvae once established will also create healthy native oyster reefs in the lough, providing shelter and food for an abundance of marine wildlife

Heidi McIlvenny, Marine Conservation Manager
Ulster Wildlife

Find out more about our ambitious restoration project to help bring back native oysters to Belfast Lough by establishing the first native oyster nursery on the island of Ireland.

Belfast Lough once supported a prolific native oyster fishery. However, overfishing, habitat loss, disease, pollution and invasive introduced species contributed to the population becoming extinct and the fishery closing in 1903. Since then, 100 years of surveys failed to document one living specimen, until 2020 when researchers from Bangor University and Queen’s University Belfast discovered 42 live oysters at six sites around the Lough. 

Heidi McIlvenny, Marine Conservation Manager at Ulster Wildlife, who is leading the project, says:

“We are still unsure how or why native oysters returned to Belfast Lough, but it indicates that the environmental conditions are right for them to establish here again. But, if they are to bounce back, they need our help.

“The biggest barrier to the recovery of the native oyster is a low number of mature reproducing oysters. The nurseries we have established at Bangor Marina are full of mature oysters that will act as larval pumps, increasing the number of oysters in the Lough and helping to restore this incredible ocean superhero for years to come.”

Native oyster nursery — Heidi McIlvenny, Marine Conservation Manager at Ulster Wildlife, and Kevin Baird, Harbour Master at Bangor Marina, examine one of the 24 native oyster nurseries housed underneath the pontoons to help the species bounce back from extinction. This is the first native oyster nursery of its kind on the island of Ireland. More at ulsterwildlife.org/native-oysters

Boosting the Lough’s fragile oyster population will also bring important benefits for other marine life, Heidi says.

“A single oyster can filter up to 200 litres of seawater, equivalent to a bathtub, per day, significantly improving water quality and reducing pollution levels. The larvae once established will also create healthy native oyster reefs in the lough, providing shelter and food for an abundance of marine wildlife, including commercially fished species, along with potential carbon storage.”

Special permissions were granted to relocate the shellfish from Loch Ryan in Scotland, which were screened for disease and cleaned on arrival before being installed in the nurseries.

Volunteers will conduct ‘health checks’ every week to ensure the oysters are thriving in their new homes. Monthly biodiversity surveys will also track changes in marine life in and around the nurseries, which form their own unique micro-habitat.

Housing the oyster nurseries under the pontoons is an innovative use of the space we have available and is a great opportunity for the marina to become an outdoor classroom, where people of all ages can get hands-on with marine conservation in an urban environment

Kevin Baird, Harbour Master
Bangor Marina

Kevin Baird, Harbour Master at Bangor Marina, says:

“We are delighted to be supporting the recovery of our most threatened marine species. Housing the oyster nurseries under the pontoons is an innovative use of the space we have available and is a great opportunity for the marina to become an outdoor classroom, where people of all ages can get hands-on with marine conservation in an urban environment.”

The oyster restoration project is funded by the DAERA Challenge Fund.   

Find out more at ulsterwildlife.org/native-oysters

Join us today and together we can BRING NATURE BACK

More about native oysters

Native oysters are one of the most imperilled habitats globally. Oyster reefs were once abundant in European seas but sadly it is estimated that populations have declined by 95% since the 19th century.
It is a Priority Species in the UK and Northern Ireland requiring conservation action because of its decline, rarity and importance in an all-Ireland and UK context. It is also included in the OSPAR List of Threatened and Declining Species and Habitats for the North-East Atlantic.
An individual oyster produces lots of larvae to ensure that some survive to adulthood – one oyster can release up to 1 million larvae per year! They can change sex, so there is always the correct ratio of males to females, and by housing oysters close together in the nursery cage it encourages them to spawn.
Left undisturbed on the seabed, native oysters will form reefs by growing on top of each other. These unique 3-dimensional habitats enhance biodiversity by providing shelter and food for a variety of species, including commercially fished species.
Native oyster reefs can act as carbon sinks due to the drawdown of sediments together with the stabilising effect of the reef, although the ecosystem benefit is complicated. However, existing oyster reefs can protect considerable stores of carbon that should be protected to avoid further releases of carbon into the atmosphere.
Many of the oysters on sale and eaten in the UK and Ireland today are pacific oysters. This is an invasive species, and was brought here intentionally from Japan in the 1970s following the demise of our native oysters,
Ulster Wildlife is creating a native oyster nursery to help restore this endangered species which is very different to an oyster farm. The shellfish are not for consumption.

More at www.ulsterwildlife.org/native-oysters