Flat oysters successfully reproduce at Borssele III & IV Offshore Wind Farm

A nature enhancement project in the Borssele III & IV wind farm reveals that flat oysters are successfully reproducing amidst offshore wind turbines. The Rich North Sea, in collaboration with wind farm owner Blauwwind, placed a total of 2,400 flat oysters at the base of wind turbines on so-called ‘oyster tables’ in 2020. It now appears that the deployed oysters have produced offspring.

Blauwwind (731.5 MW) is located about 55 kilometers off the coast from Vlissingen. Blauwwind has set up an eight-year nature enhancement project in cooperation with The Rich North Sea to monitor local biodiversity.

Last summer, a monitoring campaign by The Rich North Sea in collaboration with Eurofins AquaSense and Blauwwind confirmed the presence of young oysters near the turbines. The young oysters have established themselves on the adult oysters that were placed in oyster tables on the scour protection surrounding the wind turbines. Moreover, young oysters seem to have settled on the scour protection itself and on applied shell material.

Other insights gained from Blauwwind’s wind farm emphasize that oyster tables in an offshore wind farm provide a successful breeding ground for flat oysters. The survival rate of the adult oysters after three years is quite high, reaching 70 percent. Additionally, 88 percent of the tested oysters were found ready for reproduction. When the water temperature is sufficiently high, these oysters can start producing larvae. Finally, it has been demonstrated that in summer of 2023 larvae of flat oysters are already present in the water of the wind farm.

The fact that flat oysters have the opportunity to reproduce is a positive step forward for the North Sea’s nature. We are proud that, together with our project partners in Blauwwind’s wind farm, we could create the conditions for the oysters to reproduce.

Margot van Aalderen – Project leader The Rich North Sea

Strengthening underwater nature

The potential of offshore wind farms as a breeding ground for nature has been known. Fishing is not allowed on the seabed in the wind farm, and the hard substrate, such as the foundation and scour protection of the wind turbines, provide a suitable attachment point for shellfish and other marine life. Unfortunately, oyster reefs are no longer found in the North Sea on offshore locations. By placing flat oysters in oyster tables on the scour protection, they can now successfully reproduce in offshore wind farms. The ultimate goal for the oysters is to form a reef. The Rich North Sea is curious to see how the new oysters will further develop in the coming years in the Borssele III & IV wind farm.

It’s fantastic news that flat oysters in our wind farm are reproducing. We now have evidence that an offshore wind farm such as ours can be a suitable location as a breeding ground for flat oysters. We hope this inspires many other wind farm owners to start similar initiatives.

Michael Evans – Technical Asset Manager Blauwwind

No diseases detected

Another significant outcome is the absence of Bonamia parasites in the oysters in the Blauwwind wind farm. This is good news, as the parasite is a known pathogen that has caused significant mortality among oysters in the past. Source: The Rich North Sea

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