Matt Uttley
Blue Marine Foundation
https://www.bluemarinefoundation.com/
The Essex Native Oyster Restoration Initiative (ENORI) is a collaboration comprising of oystermen, environmental conservation groups, academia and government regulators, working hard to restore native oysters in Essex, England. Their 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.
ENORI are working within the Blackwater, Crouch, Roach and Colne estuaries Marine Conservation Zone, the only Marine Conservation Zone (MCZ) in the UK that is designated to protect native oyster beds!
Oyster beds provide a number of key ecosystem services, such as improving water clarity and quality and enhancing fish recruitment. Healthy oyster beds are hugely productive, with a rich biodiversity of associated species, and have a positive effect on the health of the entire ecosystem, diversifying the landscape and providing refuge to juvenile fish and invertebrates. However, wild native oyster stocks have declined by 90% in the UK and are now one of the most threatened marine habitats in Europe.
Essex once supported a huge oyster industry, in 1914 for example, of 22.9 million oysters (2,250t) landed in the UK, 89% were from Essex and Kent. With the loss of the native oyster industry Essex lost many of the associated environmental and economic benefits, as well as the famous culture and heritage associated with this once vibrant industry.
ENORI are working with local people, to not only facilitate the environmental restoration of the native oyster, but also reintroduce people to their oyster heritage and put Essex back on the map for its fantastic oysters!
Current ENORI members include; the Zoological Society of London, Blue Marine Foundation, Essex Wildlife Trust, Kent and Essex IFCA, Natural England, University of Essex, University of Edinburgh, The Tollesbury and Mersea Native Oyster Fishery Company Limited, the Colchester Oyster Fishery, the Environment Agency and others.
ENORI have two approaches to deliver the conservation objectives. Firstly, they have established a voluntary no-take zone called the Blackwater Restoration Box. In this 2000m2area, they are restoring the native oyster beds by adding cultch- old shell and gravels - to the seabed. This allows oyster larvae to settle and grow into mature oysters. In the first instance, this cultch addition will not only help to restore the native oyster beds but will also act as a pilot study for future restoration activities. The cultch will be laid in tracks consisting of different shell ratios and some tracks will have subsequent treatments, in order to establish what cultch conditions are most conducive to larval settlement and how best to lay cultch in the future.
The second approach that ENORI are undertakings is the creation of a ‘Mother Oyster’ sanctuary. They are translocating mature oysters into the Restoration Box, which, when spawning, will increase the number of larvae attempting to settle on the improved seabed substrate.
Once the cultch and mature oysters have been laid, they will be carefully monitored to ensure that the growth and survival rates of both the mature and new oysters are as expected and in order to deduce which cultch ratios and treatment methods are most effective within the Blackwater.
In the remaining 282km2 of the MCZ, ENORI are using adaptive management measures to, in the future, allow for a sustainable wild oyster fishery protected under byelaw to be re-opened. This has been developed in dialogue with industry, scientists and nature conservation authorities.
The first stage of physical restoration work will begin in the spring, so be sure to keep an eye on their social media pages (@EssexNativeOyster) as well as their new website (http://essexnativeoyster.com/) for all the updates and any opportunities to get involved!
Figure 1. Native oysters from Mersea, Essex.
