Millions of oysters will help restore seas off Norfolk

Plans have been revealed to build reefs on the seabed off Hunstanton, using special bricks for the creatures to live on.

Rotterdam-based conservation group Oyster Heaven, which is behind the scheme, says they would help clean up the sea by filtering the water and reducing nitrogen levels, along with providing food for birds and fish.

Special 'mother reefs' would be built on the seabed of The Wash off Hunstanton (Image: Chris Bishop)

Clay bricks will be used to form a reef on the sea floor (Image: Oyster Heaven)

If given the go-ahead by the Marine Management Organisation, the first of 40,000 bricks - each impregnated with 100 young oysters - would be laid next March.

Over the next two years, two 500m-long "mother reefs" will be created in an area close to offshore wind farm cables, where trawling and other forms of fishing are restricted.

A report by Norwich-based consultancy Exo Environmental says: "This number in the millions is necessary to have a good chance of achieving recruitment and population growth at scale.

Young oysters growing on a mother reef (Image: Oyster Heaven)

A graphic showing the decline of oyster reefs and how conservationists hope to restore them (Image: Oyster Heaven)

"The natural defence that oyster reefs have against predation, disease, storms, or other disturbance is only sustainable and effective through large colonies.

"A critical mass of oysters is required to get ecosystem take off. A deployment of 4m oyster spat will incur natural mortality in the first few years prior to growing to reproduction age.

"The project aims to reach 300,000 breeding adults, each will produce significant larvae that can help to recruit to surrounding areas."

HOW OYSTERS WILL HELP THE SEA TO STAY HEALTHY

Oysters feed by filtering the water they live in. When mature, those living on the reefs in the Wash will filter 1.7bn litres of water a day - the equivalent of 700 Olympic swimming pools.

This removes nitrogen and phosphates from the sea, making the water clearer which benefits plants and other marine creatures.

Their reefs provide nursery habitat and feeding grounds for fish and lobsters, helping to sustain populations which coastal industries depend on.

The structures also act as wave-breaks and help to trap sediment, reducing erosion.   

Oysters provide a food source for birds and marine animals - including oystercatchers (Image: Matthew Usher)

Oysters also provide food for marine birds and animals.

The report by Exo adds: "Marine recovery will not only benefit species like the native oyster from productive extinction, but it can also help resolve other challenges such as nutrient enrichment and algae smothering.

"Oyster reefs are known to provide habitat for 466 species of macrofaunal species and as such dramatically bolsters the biodiversity of the seabed, in contrast to a bare sediment." 

HOW FARMING REPLACED WILD FOOD SOURCE

An oyster farmer checks his stock in a creek at Thornham (Image: John Hocknell)

Oysters being grown on in nets at Thornham (Image: John Hocknell)

Oyster beds once covered almost a third of the bed of the North Sea, playing an important part in the ecosystem, along with a ready food source at low tide.

But over the last century the reefs have become "ecologically extinct" due to over-fishing, habitat loss and disease.

Today oysters are farmed for the table at Brancaster and Thornham to satisfy demand for the shellfish, which have gone from being a staple food in Roman times to a gastro treat costing £18 a dozen.  

Oysters, once a cheap staple food source are now a pricey delicacy on the Norfolk coast (Image: Matthew Usher)

Producers rear them in mesh bags on trestles placed in tidal creeks rich in nutrients which wash off the saltmarsh, before they are harvested for the table.

HOW SCHEME WILL BENEFIT FISHERMEN

The oyster restoration project is not intended to create a new fishery. 

But fishermen and their boats will be employed in constructing and monitoring the reefs, which will in turn help boost populations of fish and lobsters for them to catch. 

Oyster Heaven was founded in 2021 by conservationist George Birch. 

"I imagine a future where anyone, from individuals to organisations, can profitably get involved in large-scale oyster reef restoration efforts magnifying and multiplying the global effort we need to make to restore health to our oceans," he says on the group's blog.

After successful trials off the Dutch coast, the Wash will be its first major UK restoration project.

Oyster Heaven is being funded by 800,000 Euros from green investor Orange Wings and a 100,000 Euro loan from Rewilding Europe.