Oyster reefs to be built in Botany Bay and Georges River to boost fish populations and increase biodiversity

Tonnes of rocks will be barged from the Cooks River boat ramp to the reef sites in the middle of the bay, Taren Point, Coronation Bay and Audrey Bay Flat.

The rocks will be methodically placed in position on the floor of the bay and river.

The federal government is funding the project, which will be carried out by the Nature Conservancy Australia in partnership with Greater Sydney Local Land Services and the NSW Department of Primary Industries fisheries division.

The Botany Bay and Georges River Oyster Reef Restoration project was quietly established in 2021 with pandemic funding, and the first development application for the Taren Point site, east of Captain Cook Bridge was approved this month by Sutherland Shire Council.

The Nature Conservancy Australia said the goal of the project was to restore up to five hectares of the locally extinct Australian Flat Oyster (Ostrea angasi) and depleted Sydney Rock Oyster (Saccostrea glomerata) reefs, across the four sites.

Long before the arrival of Europeans, Botany Bay, or Kamay - its Indigenous name - had extensive shellfish reefs.

John Hawkesworth, on HMS Endeavour, wrote of the "great quantities of oysters, mussels, cockles, and other shellfish".

The shellfish reefs have all but disappeared, with the oyster industry almost wiped out by disease by 2001.

"In recent decades, the river's water quality has been recovering with the introduction of eco-friendly practices, land re-development, and regulations on sewage," the project brief said.

"The natural populations of Sydney rock oysters in the estuary have shown an incredible resilience with signs of good health and growth.

"With cleaner water, less pollution and a healthy remnant oyster population, Botany Bay and Georges River is ready for the recovery of these lost ecosystems.

The benefits of the new reefs would include: