Dugong population trends and declines in Australia

Australia is home to the world's largest dugong population, with about 150,000 dugongs. Habitats for this marine mammal stretch across northern Australia from Moreton Bay through Queensland’s Great Barrier Reef, Torres Strait, the Gulf of Carpentaria, and Western Australia.

Over the last two decades, declining dugong populations in some areas have raised concerns about the species' long-term health, especially in southern Queensland. Monitoring dugongs on a large scale is needed to provide insights into population trends, abundance, and distribution.

This data can determine the abundance and distribution of dugongs. It provides information on areas where populations may be struggling and offers insights into potential causes of declines, helping governments and managers to address threats and prevent further declines.

Monitoring dugong populations with aerial surveys and artificial intelligence

Our science team, along with collaborators, conducts ongoing surveys in Queensland’s Great Barrier Reef, Moreton Bay, and Hervey Bay; Western Australia’s Shark Bay, Ningaloo, and Exmouth Gulf; and the Gulf of Carpentaria and Torres Strait. 

Historically, aerial surveys relied on trained observers to manually count dugongs from aircraft across hundreds of kilometres of coastlines. In recent surveys, scientists use cutting-edge cameras attached to planes to capture thousands of images. This technology, combined with artificial intelligence, has the potential to revolutionise our ability to track and monitor marine species with accuracy and efficiency.

Most areas in the Australian dugong range are surveyed about every five years, providing a snapshot of trends in dugong numbers, including calves, and their distribution across vast areas. Key initiatives of the program include:

• Conduct large-scale surveys at regular intervals over the long term to assess dugong population and distribution trends across vast areas.

• Survey each region with consistent methods to ensure data consistency.

• Develop artificial intelligence to enhance monitoring and data analysis.

• Provide data to managers to help address threats and prevent further declines.

Queensland: dugong population and trends

In Queensland, surveys stretched from Cape York to Moreton Bay, covering almost 2,000 kilometres. A report from surveys conducted from Mission Beach to Moreton Bay was released in 2023, with the Cape York to Cairns report due late 2024.

The 2022 Dugong Aerial Survey: Mission Beach to Moreton Bay report revealed concerning trends in dugong populations. The surveys spanned from Mission Beach to Bundaberg in the Great Barrier Reef, Hervey Bay in the Great Sandy Strait, and Moreton Bay, located north of Brisbane. Key findings include:

• Surveys confirm a persistent decline in dugong numbers, especially in the southern section of the reef from the Whitsundays to Bundaberg.

• This decline is estimated at 2.3% annually since 2005.

• Low number of calves observed indicates challenges in reproduction and population sustainability.

• Areas of stable and relatively high dugong numbers include Hinchinbrook, the Townsville area, and Shoalwater Bay.

• Hervey Bay stands out with a significant population decline of 5.7% per year between 2005 and 2022. This is due to severe seagrass loss caused by back-to-back flood events in 2022. A re-survey of the area is planned for October 2024.

The 2023 report highlights the vulnerability of dugongs to environmental disturbances, especially disruptions to their seagrass habitats, which are their main food source. For the long-term survival of dugongs, healthy seagrass meadows are essential.

The report emphasises the urgent need for enhanced engagement between Traditional Owners, scientists and managers to better inform conservation efforts.

Western Australia: dugong population trends

Aerial surveys were conducted in June 2023 at Shark Bay, Ningaloo and Exmouth Gulf. The report will be released in late 2024.

There are known threats occurring in regions that could lead to the decline in dugongs.

In the Shark Bay region, increasing heatwaves have changed seagrass habitats and may have impacted populations.

In Ningaloo-Exmouth Gulf area there is potential for cumulative natural and human-driven impacts, including urbanisation and industrialisation and boating activity.

Gulf of Carpentaria and Torres Strait dugong population survey

The Gulf of Carpentaria is set to be surveyed in late 2025, with the region last surveyed in 2007.

The Torres Strait, the dugong capital of the world, has not been surveyed since 2007 and funding discussions are underway to resurvey this area.

Funders

These projects are funded by Great Barrier Reef Foundation, National Environmental Science Program, and the Department of Climate Change, Energy, the Environment and Water. Collaborators include Charles Darwin University, Edith Cowan University, Aeroglobe, Department of Biodiversity, Conservation and Attractions, and Traditional Owners.