RESTORE
Ecological Restoration of the Native Oyster Species Ostrea edulis

Photo: AWI/Mueller-Elsner

Germany
RESTORE Project

Ecological restoration of the Native Oyster Species Ostrea edulis in the German North Sea
Project duration (RESTORE II): 2019 – 2025
Project duration (RESTORE I): 2016 – 2019
Conducted by 
the Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven – Helgoland – Sylt
Funded by 
the German Federal Agency for Nature Conservation (BfN) with funds from the Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV).

The native European Oyster (Ostrea edulis) was once widespread in the German North Sea. Today, it is declared as functional extinct there – mainly due to overfishing in the era of industrialization and the early 20th century. Conservation and restoration measures are recommended under various European policies (Habitat Directive, Marine Strategy Framework Directive, OSPAR) and O. edulis is on Germany’s national Red List of endangered species. A natural recovery is currently prevented anthropogenically by on-going intensive bottom trawl fishery on other target species and ecologically by the absence of oyster populations.

The German Federal Agency for Nature Conservation (BfN) initiated the protection of this endangered species already 10 years ago. At national level, BfN commissioned and evaluated a feasibility study for the restoration of the native oyster in the German North Sea. For the implementation in the field, the research projects RESTORE I and RESTORE II were launched in April 2016 and November 2019 respectively. To address specific limitations of oyster restoration, such as seed oyster production and knowledge and technology transfer, the project PROCEED was started in November 2018. 

The projects bring together researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and the BfN Marine Nature Conservation Directorate in developing and testing applied methods for the long-term restoration of oyster stocks in the German North Sea.

Research offshore: dive operations in the German North Sea. (Photo: Alfred-Wegener-Institut / H. Mueller-Elsner)
Spat-on-Shell seed oysters prior to deployment at the pilot oyster reef in the Natura2000 site Borkum Reefground. (Photo: Alfred-Wegener-Institut / Kubikfoto)
he development of biodiversity around the oyster reef is monitored within RESTORE II. (Photo: Alfred-Wegener-Institut / Solvin Zankl)

RESTORE I

The project established the basis for developing a long-term restoration program for the European oyster in German waters. A basic requirement is the exclusion of all seabed-modifying activities such as bottom trawling or sand and gravel extraction at designated restoration sites. This requirement is met since 2023 in marine protected areas within the German Exclusive Economic Zone due to the new EU fisheries policy to exclude bottom touching activities there. The long-term goal of its ecological restoration is to establish a healthy stock of European flat oysters in the German North Sea and, to the greatest extent possible, the restoration of biodiverse, biogenic reefs – a unique ecosystem in our marine waters.

Within RESTORE I different work packages from various fields were examined in detail to get a holistic picture of legal, logistical and ecological possibilities and restrains for the future ecological restoration of O. edulis in Germany.

RESTORE I project report:
https://www.bfn.de/sites/default/files/BfN/service/Dokumente/skripten/skript582.pdf

RESTORE II

The follow-up project connects directly to RESTORE I and works on the construction, establishment and biological monitoring of a pilot oyster reef in the German marine protected area Borkum Reef Ground. The pilot reef was constructed 2020 including a stone layer and seed oysters, testing and evaluating different deployment techniques for future large-scale measures. Additionally, a monitoring protocol was developed and has been implemented and optimized on a yearly basis. The current monitoring includes imaging techniques and plankton sampling as well as recording the development of the community in and around this pilot reef, in order to scientifically evaluate the biodiversity there. 

Work packages:

  • Construction of a pilot oyster reef in the Natura 2000 site Borkum Reef Ground (BRG)
  • Construction of extended test areas in BRG with selected substrates
  • Extensive under water documentation of the reef structure
  • Evaluation of reef design and identification of suitable technologies for large scale restoration efforts
  • Development of planning and implementation guidelines for oyster restoration measures in the German North Sea Economic Exclusive Zone (EEZ)
  • Scientific monitoring of the developing ecosystem and biodiversity of the pilot reef 

For further information: