University of Portsmouth works alongside environmental agencies to put 20,000 native oysters back into harbour

Hundreds of volunteers have spent the past week preparing 20,000 native oysters for release into the harbour as part of a massive subtidal oyster reef restoration project.

Around 260 people gathered in Portsmouth from May 11-15 to help clean and inspect the oysters before they are deployed onto a newly built reef in the harbour.

The work forms part of the Solent Seascape Project, a large-scale marine restoration scheme led by the Blue Marine Foundation, Chichester Harbour Conservancy and the University of Portsmouth’s Institute of Marine Sciences.

Volunteers took part in “biosecurity days” at the university’s marine sciences institute, where the oysters were scrubbed and checked for invasive species and disease before being transferred to the reef.

The final deployment is expected to take place in Chichester Harbour on Friday, May 15, marking a major step in efforts to restore native oyster populations in the Solent.

Native oysters were once common across the area and supported coastal communities through fishing and trade, with records of oyster harvesting in Chichester Harbour dating back to Roman Britain. But numbers in the Solent have fallen by around 96 per cent over the last century because of overfishing, disease, invasive species and poorer water quality.

Marine scientists say restoring oyster reefs could bring significant environmental benefits. A single oyster can filter up to 200 litres of water a day, while reefs also provide habitats for marine life and help reduce coastal erosion.

Last month, teams completed the placement of “cultch” - a layer of shell and stone that forms the base of the new reef. The cleaned oysters will now be added to help establish a self-sustaining population.

Dr Luke Helmer, from the Solent Seascape Project, said: “This is a hugely significant moment for marine restoration in the UK. Native oysters were once abundant across the Solent, but populations have collapsed over the last century. By restoring oyster reefs at this scale, we’re helping rebuild an ecosystem that supports biodiversity, improves water quality and benefits coastal communities.”

“What’s especially exciting is the scale of public support behind this effort. Having hundreds of volunteers directly involved in preparing oysters for deployment shows how strongly people want to be part of restoring our seas.”

Ashley Hatton, from the Manor of Bosham, added: “The Manor of Bosham estate is delighted to support this environmental project, by providing the requested site in Chichester Harbour. We very much hope that the reintroduction of the native oyster species on this underwater reef will establish and thrive. Monitoring of the site, over the next five years, will determine the level of success.”