The Nature Conservancy Australia (TNC), in partnership with Port of Melbourne, are thrilled to announce the world's first trial to remediate an end-of-life dredge management ground (DMG) in Port Phillip Bay through the restoration of shellfish reefs. Dredge material grounds are areas of seafloor set aside for placement of sand and mud which have been cleared from navigation channels.
"This is an incredibly exciting initiative," Andrew Bossie, TNC's Seascapes Conservation Officer for VIC, said. "We are restoring half a hectare of new shellfish reefs over dredge material, something that has never been attempted before. If successful, this project could catalyze the remediation of end-of-life dredge material grounds in other parts of Australia and the world." Mr Bossie said.
The project will build on the existing network of successfully restored shellfish reefs in Port Phillip Bay.
Reef construction commenced on 4 February, with a mix of recycled shell from TNC's Shuck Don't Chuck project and local limestone rock to form a new reef base on the seafloor of dredge material. The reef bases will then be seeded with 400,000 Australian Flat Oysters, grown at the Victorian Shellfish Hatchery from adult brood stock sourced from an aquaculture farmer in the Bay. These juvenile oysters will be seeded onto recycled shell in the hatchery, which will then continue to grow and attach to the reef base and each other. Over time, they will create a living reef, filtering water and attracting a diversity of fish and aquatic life, leading to improved habitat value over the dredge material ground.
Shellfish reefs once dominated up to half of Port Phillip Bay's seafloor, however as a consequence of historical overfishing, compounded by catchment to coast runoff and disease, they are now considered an ecologically collapsed ecosystem.
"We are delighted to support the restoration of shellfish reefs in the Bay," Craig Faulkner, Port of Melbourne Executive General Manager Operations, said.
TNC has been restoring Australian Flat Oysters and Blue Mussel reefs in Port Phillip Bay since 2015, with a total of nearly 11ha restored to date. The reefs are already showing really promising results, with well-established populations of shellfish on the reefs and thriving wildlife around them.
"Our restored reefs at Dromana, for example, have large schools of juvenile fish including Snapper, Silver Trevally and Bridled Leatherjacket," Mr Bossie said.
This project is part of TNC's larger national shellfish restoration program that aims to rebuild shellfish ecosystems at 60 locations across Australia by 2030.
If you would like to know more about our reef restoration work in Port Phillip Bay, please visit: Victoria's lost reefs rediscovered
