Native oyster restoration

Oyster relaying

Recovery of our native oyster

Wild native oyster beds of Ostrea edulis are probably one of the most endangered marine habitats in Europe. In the UK wild native oyster populations have declined by over 95%. The loss of the wild native oysters is largely a result of historic overfishing with stock depletion being recorded as early as the first century AD.  

Recovery has been significantly impaired because of habitat loss, smothering, contamination by synthetic compounds (particularly tributyltin (TBT) antifouling paints), introduction of microbial pathogens/parasites, including the protist Bonamia, and competition from non-native invasive species such as the American slipper limpet. The loss of native oysters has been so severe that natural replenishment of their native grounds is limited and is now unlikely to occur without man’s help.

Why are native oysters and native oyster beds important?

Oyster beds used to be an important structural and ecological component of Britain’s bays and estuaries and have fuelled waterside economies for centuries. The shellfish are known as ‘ecosystem engineers’ because they provide the foundation for entire ecosystems – stabilising shorelines, filtering water and providing vital food and habitat for coastal wildlife.

Blackwater Oysterman Association preparing native oysters before re-laying in the restoration zone
Blackwater Oysterman Association preparing native oysters before re-laying in the restoration zone

What are we doing?

ZSL is working as part of the Essex Native Oyster Restoration Initiative (ENORI). The collaboration comprises of industry (Blackwater Oysterman Association), conservation groups (Essex Wildlife Trust, The Nature Conservancy, Blue Marine and ZSL), as well as statutory bodies such as Natural England, Environment Agency and Kent and Essex Inshore Fisheries and Conservation  Authority. The aim is to recover health of the Essex Estuaries with the culturally and ecologically important native oyster as its flagship species.

Hope for the future

In 2016, ENORI re-laid more than 25,000 mature native oysters in the Blackwater, Roach and Crouch Marine Conservation Zone in an attempt to restore a nationally important breeding population. The Blackwater Oysterman Association gave their time to collect and lay the oysters. Essex Wildlife Trust staff, with the support of 30 volunteers, individually marked 2,500 of the oysters to enable monitoring. The ENORI project has been supported by  Project Ocean, a ZSL/Selfridges marine conservation initiative, while the long term monitoring of the oysters will be supported by volunteer dive network Seasearch.

Project Information

Key Species

  • Native oyster (Ostrea edulis)

People Involved

Alison Debney manages the Native Oyster restoration project

Partners and sponsors

  • Essex Native Oyster Restoration Initiative (ENORI)
  • Blackwater Oysterman Association
  • Blue Marine
  • Environment Agency
  • Essex Wildlife Trust
  • Kent & Essex Inshore Fisheries & Conservation Authority
  • Natural England
  • The Nature Conservancy
  • The University of Essex
  • The Tollesbury & Mersea Native Oyster Fishery Co Ltd