Shellfish reef ecosystems are home to unique creatures and support the growth of important fish species. They also help with nutrient cycling, erosion mitigation and even coastal protection.

Historically, Port Phillip Bay, Western Port and Corner Inlet were home to large areas of native flat oyster reefs. Large areas of blue mussel reefs were also present in Port Phillip Bay. 

The State of the Marine and Coastal Environment 2021 Report looks at the current condition of shellfish reefs in Victoria.  Research by John Ford and Paul Hamer tells us that the extent of these reefs is now minimal. 

“Shellfish reefs are one of the most threatened coastal habitats. Victoria has lost more than 95% of reefs from estuarine and coastal waters since European settlement, leading scientists to classify this habitat as functionally extinct.”

- State of the Marine and Coastal Environment 2021 Report

Image credit - Jarrod Boord, Streamline Media

Fortunately, practical work is underway to restore Victoria’s shellfish reefs. Over the past six years, The Nature Conservancy has developed methods to restore shellfish reefs in Geelong, St Kilda and Dromana. Efforts have occurred in partnership with the Victorian Government, The Thomas Foundation, recreational fishers and the community. 

A combination of reseeding and reef reconstruction has led to six hectares of new reefs. In 2021, the extent of these reefs nearly doubled through the Reef Builder initiative, funded by the Australian Government. All restoration works are consistent with the Restoration Guidelines for Shellfish Reefs

The recovery of this lost ecosystem in Port Phillip has involved many sectors, including marine construction, commercial diving, aquaculture, environmental consultants and academia. Volunteers have also played a major role. Over 600 volunteers have contributed more than 3000 hours to the project, through monitoring of the reefs and hatchery preparations. 

The shellfish reefs have created habitat for a range of fish species including snapper, hulafish, little weed whiting, common bullseye and cobbler. Invertebrates such as red swimmer crabs have also colonised the reefs.
Image credit - Jarrod Boord, Streamline Media

As the scale the shellfish reef footprints grow so will the water quality benefits. An individual oyster filters 10 to 150 litres of water a day. The project’s long-term goal is to restore 100 hectares of shellfish reefs in Port Phillip Bay and develop a statewide plan to recover this lost ecosystem. 

You can read more about the condition of Victoria’s shellfish reef ecosystems in the Seafloor Integrity and Health chapter of the State of the Marine and Coastal Environment 2021 Report.