Shellfish reef found in Dutch delta
When searching for a suitable pilot location, a shellfish reef with wild flat oysters and mussels was discovered near the Brouwersdam of the coast of Holland. During one year this area was frequently monitored, to see whether the shellfish staid alive, grew and reproduced. Research was carried out by Wageningen Marine Research, Bureau Waardenburg and Sas Consultancy. Project manager Karel van den Wijngaard (ARK Nature Development): “Further monitoring of this wild shellfish reef showed out that it extended over an area of forty hectares, an area as large as 55 football fields!” Furthermore, it appears that the Dutch flat oyster (an endemic species) mainly attaches itself on Japanese oyster shells (an exotic species). Possibly the Japanese oyster can facilitate the recovery of the flat oyster, also in other areas.
Importance of shellfish reefs
Twenty percent of the North Sea bottom once consisted of shellfish reefs. These reefs disappeared due to overfishing, destruction of habitats and diseases. They are, however, of great importance. For example, the shellfish offer a resting area and nursery for young fish and other aquatic animals. The shellfish are also food for fish and birds and serve as a support for plants and animals to grow. In addition, they filter the water, which improves the water quality. Shellfish reefs are used worldwide as natural coastal defenders. They filter out sludge and algae from the water and separate it again in the lee of their shells. They raise sandbanks and protect the coastline against high waves and storms.
Foundation for recovery
Given the size of the oysters in this reef, the bottom of this area has been left undisturbed for at least ten years. ARK and the World Wildlife Foundation made an appeal to the government and stakeholders to close this reef for protection. The reef provides a lot of knowledge about the development of shellfish and it is, as far as is known, the only place in the North Sea where flat oysters grow in a vast structure. The shellfish reef at the Brouwersdam provides an important foundation for the recovery of wild shellfish in the North Sea and a hotspot of natural wealth.