Welsh oysters to be transferred into River Hamble in Solent reef plans

Ocean conservation charity Blue Marine Foundation, alongside the River Hamble Harbour Authority and contractors Jenkins Marine, laid the foundations for the largest restoration reef in the Solent last week.

They laid a thin veneer of shingle mixed with cockleshells, known as ‘cultch,’ covering 2,500 metres square onto the seabed.

Oysters sourced from south Wales will be transferred to the site to seed the area at the Swanwick bend in the River Hamble in a few weeks, after being cleaned, measured and checked.

The Solent was once the largest and most important oyster fishery in Europe, the charity says, but over the last decade oysters have significantly dwindled in numbers as a result of poor water quality, competition from invasive species, disease and fishing pressure. 

The loss of the native European oyster not only negatively impacts the livelihoods of local fishermen, but also removes the many ecosystem services that a healthy oyster population provides.  

Adult oysters can filter as much as 200 litres of seawater each day, improving water clarity and removing excess nutrients. 

The work is part of the Solent Seascape Project, a multi-million-pound scheme funded by the Endangered Landscapes Project.

Louise MacCallum, Solent Project Manager for Blue Marine said: “This new restoration reef has taken more than a year to plan. 

“The River Hamble is one of the busiest waterways in the UK.  

“As well as creating a perfect home for 30,000 oysters, it has also been critically important to ensure that our operations do not affect navigational safety for the many people who enjoy boating and water sports on the river.”

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In the coming months and years scientists from Blue Marine, University of Portsmouth and University of Southampton will monitor the new reef.  

Oyster survivorship and biodiversity gains will be measured and compared to another part of the river where no restoration activity is to take place.

Louise said: “This will be our second restored oyster reef in the Solent, the first having been built in Langstone Harbour at the end of 2021. 

“The Langstone reef has already attracted a wealth of marine fauna including cuttlefish, catsharks and even seahorses.  

“It is exciting to see what kinds of marine creatures our new reef will attract in the River Hamble.”

In 2021 the Solent Seascape Project team restored a 1,000 square metre oyster reef in Langstone Harbour.  

To date, this existing reef and the new reef in the River Hamble are the only restored reefs in the Solent region.

Marine habitat restoration is in its infancy in the UK.

As well as restoring oyster habitats, the Solent Seascape Project team will be restoring seagrass meadows, seabird nesting habitat and salt marsh across the Solent region.

As the project progresses the team hopes to use the lessons learned to create a blueprint for restoring temperate marine habitats elsewhere in the UK, and beyond.