Video report from ITV News Meridian's Chlöe Oliver
A project to restore what was once Europe's largest oyster fishery is underway at a site in Southsea.
The hatchery, the first in the UK, is rearing millions of oysters that will be released into the Solent once they're fully grown.
Researchers at the University of Portsmouth and the Blue Marine Foundation (Blue) hope the scheme will restore the oyster industry across the south coast - but they also say it will improve water quality.
Dr Jo Preston from the University of Portsmouth explains how they grow oysters
The hatchery plans to produce enough larvae to replace the population of the Solent, which once numbered in the millions.
It takes local oysters and gives them the correct temperature and diet, which then encourages them to breed.
The larvae are then left to settle on old oyster shells, which will then be placed on the seabed in the hope they will grow and begin to repopulate.
The pioneering project is focused around Langstone Harbour, near Portsmouth.
"We have a variety of techniques to restore our native oyster," says Dr Luke Helmer from Blue.
"We've got our nursery system where we placing adults in close confinement so they can reproduce and release larvae into the harbour and other areas of the Solent."
They've been preparing the seabed across Portsmouth and the River Hamble.
It's also deploying 'cages' onto the seabed, that give marine animals a safe habitat to live.
"We'll have a 100,000 oysters to begin with, then [aim to] develop that throughout the year."
It aims to restore populations that in the past were drastically affected by pollution, overfishing and invasive species.
The threat to the molluscs was so great that fishing them was banned in 2013.
"We've worked with the fisherman throughout and it's very important to have them involved," Dr Harmer said.
But he added that it could be "20 years down the line" before the population is likely to start "expanding into areas that can be sustainably fished."