Good news for fishers: results of oyster reef study promising

More fish and cleaner water.

That’s the results of a detailed study of NSW’s first restored oyster reefs at Port Stephens.

The Port Stephens Oyster Reef Restoration project involved the construction of rock bases across 7.5 hectares of bare sand and mud in the Port Stephens-Great Lakes Marine Park.

More than 55 million baby oysters (called oyster spat) have colonised the reef base creating a living and growing oyster reef since its construction in 2020.

DPI (Department of Primary Industries) Fisheries Marine Biologist, Dr Victoria Cole, has been studying the impact of the newly restored oyster reef on fish and water quality.

She said results from monitoring the reef show significant changes are taking place.

“The impact of the new reefs on numbers of fish were impressive, with our results showing there are up to 50 times more juvenile fish on the new reef than on the bare sand,” she said.

“The new oyster reefs increase the availability of food and shelter for fish. In addition, smaller fish sheltering in the crevices of the reef draw in bigger fish feeding on the smaller fish and invertebrates, creating a more diverse ecosystem,” Dr Cole said.

The types of fish recorded on the new reef during her study also varied from that of the bare sand.

“Instead of finding the types of fish you find on bare sand such as Mullet, Whiting and Toadfish, we were seeing species that you’d expect on natural oyster reefs like Bream, Oyster Blennies and Luderick.”

“As the restored reef at Port Stephens is only two years old, we are still seeing the shift to a full oyster reef ecosystem.”

Dr Cole said her research showed that the restored oyster reef contributed to improved water quality even in its first few years.

“We found that the oysters on the restored reef were filtering almost as much water as those on the natural reefs,” she said.

“By finding the average filtration rate of the new reefs and multiplying this by the total area of restored reef, we calculated that the newly restored reefs are filtering approximately 7.5 million litres, or three Olympic swimming pools of water an hour,” Dr Cole said.

Dr Cole presented her research on the Port Stephens Oyster Reef Restoration at the Australian Marine Sciences Association conference in Cairns in August.

Find out more about the restoration project at our website or through checking the infographic research summary.

The Oyster Reef Restoration project is conducted by DPI Fisheries and funded under MEMS (Marine Estate Management Strategy) in partnership with The Nature Conservancy through the Australian Government’s Reef Builder initiative.