As part of the BELREEFS flat oyster reef restoration project, a dedicated monitoring program was developed by the Royal Belgian Institute of Natural Sciences, following key parameters defined by the Native Oyster Restoration Alliance (NORA) and adapted to challenging offshore conditions. Jan De Nul designed custom monitoring cages that allow standardized, long-term monitoring. These cages can be recovered either via an acoustic release system or by scientific divers.
The first monitoring cage was successfully retrieved in September 2025, two months after the installation of the first volume of oysters in July 2025*, using the acoustic release system. Researchers assessed oyster survival, growth, and density, searched for the settlement of wild oyster spat, and identified both attached and mobile species colonizing the clay stones. Laboratory analysis confirmed oyster survival and growth, indicating a promising start for the restoration of offshore oyster reefs in the Belgian part of the North Sea! The detection of wild oyster recruitment was considered particularly encouraging. The researchers also took note of active ecological interactions, including space competition and the presence of potential predators.
Further monitoring is planned over the coming years, with two additional cages to be retrieved. These long-term observations will provide critical insights into reef development, ecological dynamics, and the effectiveness of offshore oyster reef restoration, supporting future large-scale restoration efforts in the Belgian North Sea.