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. 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 our help.
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 – filtering water and providing vital food and habitat for coastal wildlife.
Blackwater Oysterman Association preparing native oysters before re-laying in the restoration zone
ZSL is working collaboratively to deliver and encourage the recovery of native oysters. This is an area of marine restoration that is rapidly growing as a promising method of increasing biodiversity and improving coastal water quality as well as protecting the threatened native oyster. Find out more about these initiatives below.
Essex Native Oyster Restoration
ZSL is chair of the Essex Native Oyster Restoration Initiative (ENORI). The collaboration comprises oysterman, environmental conservation groups, academia and government. Our shared vision is for the Essex estuaries to have self-sustaining populations of native oysters that provide ecosystem services, sustainable fisheries and increased biodiversity whilst recognising their cultural importance.
In 2013 the Blackwater, Crouch, Roach and Colne Estuaries Marine Conservation Zone was designated by the UK government with the conservation objective of recovering both native oyster beds (the habitat) and native oysters (the population) - this is the only protected area in the UK for native oyster beds. At 284km2, it is the largest protected area for native oysters in Europe.
We have two approaches to deliver the conservation objectives. We have established a voluntary no-take zone called the Blackwater Conservation Box. In this 200 hectare area, we are restoring the native oyster beds and we are doing this by adding cultch- old shell and gravels - to the seabed. This allows juvenile oyster spat to settle and grow into mature oysters. In addition, we are creating a ‘Mother Oyster’ sanctuary where we are translocating mature oysters who will spawn and settle on the improved seabed substrate.
In the remaining 282km squared, we are using adaptive management measures for a sustainable wild oyster fishery protected under byelaw. This has been developed in dialogue with industry, scientists and nature conservation authorities.
You can find out more about the initiative on our website.
The Native Oyster Network - UK and Ireland is a newly formed national network, that has been established in collaboration with ZSL and the University of Portsmouth. The network aims to facilitate an ecologically coherent and collaborative approach to native oyster restoration across the UK and Ireland. To do so, the network will facilitate effective communication and collaboration between the current native oyster restoration and research, and work to increase the awareness of the social and political worth of native oysters. Further to this, we hope to develop volunteering and opportunities for the general public to become engaged with the network.
At present, there are a number established native oyster restoration projects across the UK and Ireland, located in Portsmouth, Essex, Scotland, Wales and Ireland. Each project has several different stakeholders involved, including local fishermen, NGO’s , fisheries authorities, University researchers and students. We hope to see the number of restoration projects in the UK increase, with the support and knowledge shared through the new network. With the long-term goal of developing sustainable native oyster populations across the UK and Ireland.
Find out more about the network on their website here: http://nativeoysternetwork.org/
Alison Debney manages the Native Oyster restoration project
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