Reef Builder Monitoring and Evaluation Report. A report prepared for the Department of Climate Change, Energy, the Environment and Water.

Reef Builder was a partnership between the Australian Government and The Nature Conservancy Australia (TNC) with the ambitious goal of rebuilding lost shellfish reef ecosystems at 13 projects across southern Australia. With 21 shellfish reefs now restored to date, it has provided a significant boost towards TNC’s broader goal of rebuilding 60 reefs across Australia by 2030 and recovering 30% of these lost habitats for the benefit of both people and nature.

Shellfish reefs, created when millions of oysters and mussels settle onto each other, are natural solutions to some of our greatest conservation challenges. They improve coastal water quality, boost fish stocks, provide homes for a diverse range of sea life, generate regional employment, and protect Australia’s coastal communities and shorelines from coastal erosion.

Once expansive across Australia’s estuaries and bays, most of these natural habitats have been decimated since the 1800s by years of commercial harvesting, sedimentation, pollution, introduced species and disease. Fewer than 8% of our natural shellfish reefs remain across southern Australia’s coastline today, rendering them functionally extinct.

Reef Builder was an AU$20 million Program of work carried out between January 2021 and December 2023 to rebuild shellfish reefs at 13 projects across Western Australia, South Australia, Victoria, Tasmania, New South Wales, and Queensland to accelerate the recovery of our lost shellfish reef ecosystems. It builds on the demonstrated success of TNC and local delivery partners in restoring these vital habitats at multi-hectare scales across southern Australia since 2015.

The primary aims of Reef Builder were to (1) restore Australia’s estuarine and coastal ecosystems through rebuilding a critically endangered marine ecosystem, improving local biodiversity and boosting fish populations, and (2) provide economic stimulus to shellfish aquaculture, marine engineering, construction, monitoring and ecotourism businesses in coastal and regional communities.

The primary purpose of this report is to summarise key analyses of the ecological, social, and economic data collected during the Reef Builder Program to determine the level of success in achieving the Program targets and goals. It further outlines the monitoring and evaluation approach used to help inform future large-scale shellfish reef restoration efforts in Australia and worldwide.

This work is complemented by the Reef Builder Summary Report (10.5281/zenodo.11516466) which provides an overarching synthesis of the key ecological and socioeconomic outcomes of the Program, and includes a selection of project case studies which help share the story of our three year delivery journey. It also includes key lessons learnt, as well as anticipated next steps towards 2030.