Green Turtle Research Program

Six of the world's seven species of marine turtle live within the Great Barrier Reef World Heritage Area © Great Barrier Reef Marine Park Authority

Six species of marine turtle are found on the Great Barrier Reef. The Reef region has globally significant nesting and foraging areas for green, loggerhead, hawksbill and flatback turtles. Marine turtles provide a number of ecological services, including herbivory and seagrass dispersal by green turtles, nutrient cycling and sediment production. Turtles are highly valued by Traditional Owners, visitors to the Reef and the local community.

Years of monitoring indicates that the northern Great Barrier Reef green turtle population is in decline. Raine Island is the world's largest green turtle rookery and monitoring indicated a 20-year failure to produce sufficient green turtle hatchlings to maintain a sustainable population.

About 90 per cent of the northern Great Barrier Reef green turtle population nest on Raine Island or nearby Moulter Cay.

Management interventions implemented in recent years as part of the Raine Island Recovery Project, (a partnership between Great Barrier Reef Foundation, BHP, the Queensland Government, the Great Barrier Reef Marine Park Authority, and the Wuthathi and Meriam Nation (Ugar, Mer, Erub) Traditional Owners), have slightly improved reproductive success.

Rising air and sand temperatures as a result of climate change are the most immediate and broad-scale threats to marine turtles because the gender of hatchlings is determined by temperatures experienced within the nest. The feminisation of green turtles originating from nesting beaches in the northern Great Barrier Reef, is predicted to lead to a significant scarcity or absence of adult males in the future.

Other impacts on green turtles indicated by current research include a decline in the size of nesting adults, increases in the non-breeding periods, a lack of expected increases of turtle numbers in dispersed feeding areas, and increased flooding of nest chambers.

What is the Green Turtle Research Program?

The Great Barrier Reef Green Turtle Research Program, a three-and-a-half-year, $5.93 million research program proposes a series of activities aimed at improving our understanding of the northern Great Barrier Reef green turtle population and to inform a range of management activities, including how best to respond to the impacts of climate change. Another key outcome is to enhance the co-management capacity of those Traditional Owners of whose country these iconic species forage and nest.

Turtle on Raine Island - photo © Mark Read

Raine Island Recovery Project is a partnership between Great Barrier Reef Foundation, BHP, the Queensland Government, the Great Barrier Reef Marine Park Authority, and the Wuthathi and Meriam Nation (Ugar, Mer, Erub) Traditional Owners.

Key components to the Green Turtle Research Program

• A one-off, broad-scale aerial survey of all potential nesting beaches (mainland and islands/cays) in the northern Great Barrier Reef and Torres Straits. The primary aim of this project component is to provide an up-to-date understanding of how dispersed the northern Great Barrier Reef green turtle nesting population is and to quantify just how important Raine Island and other rookeries are as nesting sites.
• Determining the movement patterns and foraging grounds of adult male green turtles from the northern Great Barrier Reef green turtle population. All the emerging information indicates that elevated incubation temperatures mean it is critical to protect every adult male green turtle in the northern Great Barrier Reef population. The aim of this project is to satellite track 40 adult males captured at Raine Island and the Torres Strait to see where their foraging grounds are and then review the adequacy of protection at those locations.
• A three-and-a-half-year study to better understand how the foraging ground component of the northern Great Barrier Reef green turtle population is functioning. It is proposed to establish new foraging ground study sites in both the far northern Great Barrier Reef and in the Torres Strait and undertake a study to catch, measure, tag and take tissue samples from a representative sample of all size classes of green turtles at those sites. As part of this component we'll undertake an analysis of the health (as indicated by pollutant and contaminant levels) and genetic composition of green turtles from tissue samples collected at these foraging grounds referenced against samples collected at other sites in the northern Great Barrier Reef.
• Additional support for a pilot study at Mon Repos Conservation Park (initiated by the Department of Environment and Science) to trial how to effectively cool turtle nesting beaches to temperatures (at clutch depth ~80 centimetres) that are likely to produce a higher proportion of male hatchlings over the required time period. The aim is to conduct the experimental work at Mon Repos (an easily accessible turtle nesting beach) in the first instance, with a view to (in the future) applying positive results at important sites for the northern Great Barrier Reef green turtle population at ecologically-meaningful scales.
• A dedicated extension and outreach project to socialise the results of the Great Barrier Reef Green Turtle Research Program and the Raine Island Recovery Project throughout the Torres Straits and northern Great Barrier Reef, particularly highlighting the impact of incubation temperature on the sex ratios of hatchlings and the relative importance of the different sexes and size classes of green turtle in the population. It is proposed to engage a communications consultant to work with Traditional Owners and members of the project team to develop culturally-appropriate messaging and material and then visit a number of communities throughout the northern Great Barrier Reef and Torres Strait to present and discuss these findings. The intended outcome of this project is to reinforce messages about the importance of protecting important turtle nesting and foraging habitats that support the northern Great Barrier Reef green turtle population. As part of this project, written material and web-based information in both local language and English are proposed.

Activities will be conducted in partnership with Traditional Owners and will enhance the capacity of the Indigenous rangers who manage turtle habitats on country. Project staff will shortly begin engaging with partner agencies and Traditional Owners to ensure the program meets all their needs and aspirations.