Restoring the lost shellfish reefs in the Derwent River
Restoring lost shellfish ecosystems
Tasmania, although isolated from mainland Australia, doesn't fall short of natural beauty. Revelling in diverse landscapes from coast to coast, it’s known for harbour views and heritage charm, due in part to cities like Hobart.
It’s also part of a long marine history, which was once the home of abundant shellfish reefs that supported wildlife and local communities.
A history of Tasmania's oyster reefs
Australian Flat Oysters (Ostrea angasi) were once common throughout Tasmanian waters and were an important food source for Tasmania’s Indigenous communities. For thousands of years before European settlement, Indigenous Australians sustainably harvested oysters.
Oyster reefs fell into decline
In the 1800s following European settlement, oyster reefs were intensely harvested until the fishery collapsed.
The oyster reefs at Georges Bay, on Tasmania’s East Coast are the only known remaining reefs in the area. Sadly, less than 1% of these unique ecosystems remain in southern Australia.
See why we're restoring shellfish reefs in Tasmania
The Derwent River Shellfish Reef Restoration project
As part of the national Reef Builder partnership with the Australian Government, TNC partnered with Natural Resource Management South to deliver this Reef Builder project.
The project restored Australian Flat Oyster reefs at 2 sites in the Derwent Estuary and D’Entrecasteaux Channel, creating 1.4 hectares of new oyster reefs.
NRM South and TNC worked closely with the aquaculture industry, marine industries, the marine science community, Traditional Owners, Tasmania Association for Recreational Fishing (TARFish) and the local community in the delivery of this project.
The reefs are coming back to life
A diversity of fish species have been monitored on the reefs, including Common bullseye, Goby, Hardyhead, Hulafish, Jackass morwong, Sand flathead, Rock Lobsters, Banded Stingaree and natural recruitment of Australia Flat Oysters. This shows that even in a short amount of time, these reefs are providing important habitat.
It doesn't stop here
Whilst monitoring frequency naturally changes as the restored reef becomes settled, the reefs are still monitored for changes.
In December 2024, TNC divers undertook a rapid assessment of the reefs primarily to see how oyster growth and survival was tracking and observe other biodiversity such as fish species.
TNC have ambitions to restore more reefs in Tasmania as part of our target to restoring reefs in 60 locations by 2030.
For more information on the achievements of the Reef Builder initiative, read the 2024 Reef Builder Final Summary report.