RESTORE preliminary investigation

Project duration 2016-2019

In order to sustainably restore the European oyster’s population, conservation, technological, and biological issues first needed to be addressed before defining final recommendations for a long-term restoration program.

Goals

Within the framework of the present E+E project, scientific and technological bases for the restoration of European oyster stocks in the German North Sea need to be developed. Following the given framework of nature conservation laws, a variety of technologies for settlement were tested in field studies at possible restoration sites where growth and fitness of the animals were measured. In particular, the following insights were expected:

• Estimates on growth and fitness of the oysters (biological suitability)
• Identification of donor populations (seed oysters for reintroduction)
• Recommendations on suitable sites
• Recommendations on suitable technologies

Results:

As part of the preliminary investigation in spring 2017, European oysters were put inside oyster cages, and deployed in the offshore maritime area north of the island of Helgoland. An additional site within in the MarGate research field off Helgoland, complemented the surveys since fall 2017. Growth and fitness studies (health, reproduction) were regularly conducted on the young oysters. Samplings were done by AWI’s research divers working on our research vessels FS Heincke, FS Mya II and FK Uthörn. Further studies were carried out at the AWI laboratories in Helgoland, Sylt and Bremerhaven.

The results showed excellent growth, and a good health status of the European oysters. The biological suitability for future restoration measures was evaluated as positive based on these results.

Further experiments resulted in comprehensive insights into the settlement behavior of the larvae of the European oyster on the substrates present in the German Bight. Successful larval settlement is an important component for long-term reintroduction.

Based on relevant site selection criteria, several sites within the “Borkum Reef ground” marine protected area were identified as suitable for future restoration efforts. There, a first pilot reef for further investigations on a successful restoration of the European oyster in the German North Sea was established in summer 2020, as part of the next phase, the RESTORE main project.

Supported by the Federal Agency for Nature Conservation (BfN) with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.