The Belgian pilot will be developed in an offshore wind farm, operated by Parkwind in Belgian territorial waters
Before 19 century oyster reefs used to be abundant and oysters were common source of protein for the locals.
The scour protection around wind turbine poles may encourage the formation of natural oyster reefs
Cross-fertilisation between oyster aquaculture and oyster reef restoration is expected to create synergy
Rise and fall of the European flat oyster
The European flat oyster (Ostrea edulis) is a luxury seafood, considered a more valuable and marketable product than the Pacific oyster (Crassostrea gigas). Indigenous to Europe, the flat oyster has been part of our diet for many centuries. Oyster spat – the young oysters – has been collected from rocks for grow-out in ponds since Roman times, and flat oyster aquaculture flourished in Europe in the 18th and 19thcenturies. However, overfishing since the 19th century and the occurrence of diseases (such as bonamiasis) in the 1980s devastated wild oyster reefs, and recent efforts to obtain cultivated spat have not been successful, with unexplained deaths of larvae and spat. With wild spat becoming rare, aquaculture of flat oyster is now impossible in most traditional rearing areas.
In Belgium, flat oysters used to be abundant and formed large oyster reefs, a valuable habitat supporting a unique marine biodiversity. What used to be a key element of the country’s biodiversity, cuisine and culture, is almost extinct today.
Will we have to give up eating delicious plates of flat oysters? Maybe not: Belgian offshore wind farms might offer a unique environment to interactively restore oyster reefs and develop aquaculture. Bottom fishing is not allowed in wind parks – and oyster reefs would thus not be damaged. In addition, the hard substrate used as scour protection around wind turbine poles may be the perfect substrate for oyster larvae to settle on and initiate natural oyster reefs. Aquaculture could be developed hand in hand with restoration efforts, as the two activities would enhance each other: aquaculture would provide the initial stocking material to help developing natural reefs and, in the longer term, natural oyster reefs would provide oyster larvae to the aquaculture sector.
Co-location of restoration and aquaculture in wind parks looks like a logical choice, but we are still far from its large-scale application. The distance from the coast complicates implementation, operation and maintenance of the structures needed for restoration and aquaculture production, and the same can be said about the harsh sea and weather conditions in the North Sea. Optimal growing conditions of flat oyster are quite specific, and this makes offshore aquaculture and restoration very challenging. The selected scour material must fulfill the technical requirements imposed on scour material in general and, at the same time, it should create an attractive habitat for oyster larvae to settle.
UNITED scientists are addressing these challenges by finding the best technical and managerial solutions in a pilot wind farm within the designated zone for offshore wind in the Belgian offshore space (exclusive economic zone). Models to correctly position the longlines are applied, proper systems for spat collection and grow-out are being developed, and several scour protection materials are being tested. In addition, they are combining the culture of flat oyster and sugar kelp on the same longline, and comparing the characteristics of sugar kelp grown nearshore and offshore.
If aquaculture and restoration prove to be feasible in offshore wind farms, a new time of prosperity might start for flat oyster. This blueprint could open the way for new multi-use sites in Belgium, and all we will need to worry about will be: shall we season our flat oysters with lemon, or shall we enjoy their natural open-sea taste? With an additional pleasure: the certainty that flat oysters in our plate have contributed to the restoration of natural beds and the flourishing nature that goes with them.