The return of the flat European oyster

European researchers are trying to revive Europe’s native oyster, that over the last century has become almost extinct.

Read the original French article here.

The European flat oyster used to be everywhere: Until the middle of the 20th century, Ostrea edulis was fished, farmed and eaten from the North Sea to the Adriatic, from Norway to Croatia.

Overfishing, but mostly the arrival of the two parasites Marteilia and Bonamia in the 1970s and 80s, which reached Europe through trade globalisation, decimated the populations. Of this unique species native to the continent, only a handful of wild sites remain today.

In France, a small number of oyster farms still exist, mainly in the Bay of Mont-Saint-Michel, an area slightly more protected from disease. The production of flat oysters does not exceed 1,000 tonnes per year, whereas hollow oysters produce around 80,000 tonnes.

The common oyster we eat the most today is a species from Japan called Crassostrea gigas, which is much hardier than its European cousin.

European Native Oyster Restoration Alliance

In 2017, a hundred or so European scientists and managers joined forces to help the flat oyster reclaim the coast, by creating the Native Oyster Restoration Alliance (NORA).

Since then, projects have been set up across a dozen member states.

In France, the Comité Régional Conchylicole de Bretagne Nord (CRCBN) is preparing the return of the Ostrea edulis. After identifying the last natural beds and carrying out several biological and ecological studies on the species and its environment, the first experiments to recolonise the marine environment began in Finistere, in western Brittany.

They produce oyster “families” in tanks fixed on artificial reefs made of biomaterial supports, before placing them at sea on wild beds.

The project, called ARCHE, which is 80% funded by the European Maritime, Fisheries and Aquaculture Fund (EMFAF), was launched in 2018 and will be completed in March 2023.

“Some of the reefs have been in the water for two years, and we are satisfied, optimistic for the future,” Benoît Salaun, director of CRCBN, told EURACTIV France, adding that as it takes three years for a oyster to fully grow, the project is not finished and experiences are yet to be made.

To avoid a new wave of contamination and make large-scale farming possible again, the most parasite-resistant shellfish have been selected in advance.

Artificial reefs containing flat oyster larvae as part of the ARCHE project (photo CRC Bretagne-Nord)

Nevertheless, some questions remain unanswered. Will the implantation in the open sea work, despite an environment subject to various hostile elements? Will these oysters manage to reproduce with their wild relatives and pass on their resistance?

In Belgium, the UNITED 2020 project also embarked on this type of restoration, particularly in the wind farms of the North Sea.

A little further north, around the Heligoland archipelago, Germany is designing an oyster hatchery for restocking broodstock as part of the PROCEED project (2018-2024).

Benoît Salaun stressed the common European will to revive the flat oysters.

“We are working on improving the strains, on selection, in particular with the Wegener Institute in Germany. We are even going as far as exchanging families of oysters, to have more diversity.”

Hazelnut taste

Another of NORA’s objectives is to restore marine habitats and the entire ecosystem. The oyster is an ‘engineering’ species, which creates natural reefs that attract rich biodiversity and trap carbon. It also filters water, which allows algae to better absorb light.

For professionals, the development of the flat oyster will open up the market and reduce the health risks associated with monocultures.

Although France is the main producer and consumer of flat oysters, some other member states are promoting their own farms, such as Ireland, with Galway’s flat oysters, or the Ston oysters from Croatia.

Can a prodigal return of Ostrea edulis be expected in the next years?

“If we reach 10%, it will already be a success,” said Benoît Salaun. “But it is the consumer who will decide.”

Whether the very iodized taste with a hint of hazelnut will delight the European palate remains to be seen. The price will also be twice as high as that of the hollow oysters, at between €10-15 per dozen.


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