New tool to drive restoration of historic native oyster reefs

A new tool to help increase the native oyster population around the English coast has been launched, the Environment Agency announced today (World Oceans Day 8 June).

Native oyster populations have decreased by 95% in England since the mid-1800s, mainly due to over-fishing.

The aim is to reverse this decline because they bring multiple benefits, including cleansing seawater through filtration and increasing biodiversity and fish abundance.

Developed by academics from the University of Exeter and the University of Edinburgh for the Environment Agency, the new map data layer is on the ArcGIS (geographical information service) site and provides information on the location of historic native oyster records and distributions.

It will also sit on the Coastal Data Explorer, which is a public web mapping portal managed by the Catchment Based Approach initiative.

It can act as a tool to support local authorities, community partnerships and environmental organisations to make the case for native oyster restoration projects, one of the three estuarine and coastal habitats that are the focus of the Restoring Meadows, Marsh and Reef (ReMeMaRe) habitat restoration partnership project.

The layer works alongside the Environment Agency’s Native Oyster Restoration Potential maps that highlight areas where oyster restoration could be successful, and the UK & Ireland Native Oyster Network and Environment Agency’s European Native Oyster Habitat Restoration Handbook that provides guidelines on how to restore these valuable habitats.

The handbooks and maps aim to counter the huge loss in native oyster reefs over the last two centuries by encouraging and supporting new restoration projects.

The map layer was created using data from government, and scientific and maritime bodies, and historic media accounts that mention the use and presence of the native oyster, Ostrea edulis, across England.

Environment Agency Estuary and Coast Planning Manager Roger Proudfoot said:

The release of this information on where native oyster reefs were once present represents another milestone in our drive for more estuary and coast habitat restoration.

We have lost 95% of our native oysters mainly due to over-fishing. As well as being catastrophic for our marine ecosystem, we have also lost the multiple benefits that they once provided for us, including cleansing our waters through filtration and increasing biodiversity and fisheries.

We hope this new information on the historic locations of once thriving oyster reefs will lead to new opportunities for restoring what has been lost. We know that oyster restoration is possible, we just need more capacity to upscale the current efforts and we look forward to this new information inspiring more projects to restore this magnificent mollusc.

Dr Ruth Thurstan, Project Lead and Senior Lecturer at the University of Exeter said:

Oysters once formed an understated but important part of British marine ecosystems and popular culture.

“In the 19th century we fished and consumed oysters by the millions, while their complex reef habitats were key to supporting other marine life that we valued and depended upon.

Much of this was lost as oyster habitats declined, and our marine ecosystems today are fundamentally different. This map of historical oyster fisheries is a step towards building the knowledge base required for successfully restoring this culturally and ecologically important species in our coastal waters.

Dr Philine Zu Ermgassen, Project Lead and Research Associate at the University of Edinburgh said:

The habitats formed by the native oyster have declined precipitously and are now rarely found. This largely happened outside of living memory.

Evidencing where fisheries were historically is the first step toward a greater understanding of the former extent and importance of oyster habitats. Knowing where oyster habitats were found is important both for public understanding and for local decision making. Both are critically important as habitat restoration efforts take off across England and the rest of Europe.

Further details of native oyster restoration efforts can be found through the Native Oyster Restoration Alliance https://noraeurope.eu.