Marine conservation:
Ecological Restoration
of the native oyster species Ostrea edulis

Photo: AWI/Mueller-Elsner

Restoration Projects Germany – RESTORE

Background:

In the German North Sea, where it was historically widespread, the native European Oyster (Ostrea edulis) is functional extinct 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 and. A natural recovery is currently prevented by on-going intensive bottom trawl fishery on other target species.

The German Federal Agency for Nature Conservation (BfN) initiated protection and investigation of this endangered species several 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 in November 2019. 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 from 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.

Project RESTORE II

Project beneficiary: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven – Helgoland – Sylt 
Project funding:German Federal Agency for Nature Conservation (BfN)
Project term: 2019 – 2023

Work packages:

  • Construction of a pilot oyster reef in the Natura 2000 site Borkum Reefground (BRG)
  • Construction of extended test areas in the NCA 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)
  • Pilot tests in the NCA “Helgoländer Felssockel”

Project RESTORE I

Project beneficiary: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven – Helgoland – Sylt
Project funding:German Federal Agency for Nature Conservation (BfN)
Project term: 2016 – 2019 

Work packages:

  • Review and setting the legal framework for oyster restoration in Germany
  • Knowledge transfer with international oyster restoration projects and establishment of an European network
  • Identification of suitable areas for oyster restoration (site selection)
  • Identification of suitable seed-oyster sources and substrate technology
  • Lab and field experiments to study settlement preferences of O. edulis larvae
  • Field experiments to study growth, fitness and health of O. edulis in the sublittoral
  • Engaging potential stakeholders: e.g. fishery and mariculture

Goal:

The project established the basis for developing a long-term restoration programme 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 may be met in marine protected areas within the German Exclusive Economic Zone, although this is dependent on ongoing negotiations within the EU common fisheries. Within RESTORE, the first experiments were conducted in the fishery closure zone around an offshore windfarm near Helgoland, where seed oysters were deployed and their fitness and survival were monitored closely.
The long-term goal 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 – an unique ecosystem in our marine waters.

Some recent results:

Please look here:
https://www.awi.de/en/science/biosciences/shelf-sea-system-ecology/main-research-focus/european-oyster.html
https://www.bfn.de/en/activities/marine-nature-conservation/marine-arten/artenschutzprojekte/restoration-of-the-european-flat-oyster.html