[Editor’s Note: Roughly 60,000 green turtles use Raine Island as a nesting ground every year.]
Raising the height of part of the world’s most important green turtle nesting site has helped researchers save precious eggs and hatchlings on Raine Island, north-west of Cairns.
Eye-in-the-sky monitoring from drones deployed for the first time confirmed the success of the project, which ensured the re-shaped island area remained above the flooding level throughout the 2015-2016 nesting season.
Minister for National Parks and the Great Barrier Reef Dr Steven Miles welcomed the findings from the “bold conservation project’ to keep the beach stable, and turtle eggs safe.
“In response to the dramatically-high egg mortality from tidal inundation, and to increase the viable nesting area, the proactive decision was taken to raise the height of a 150 metre stretch of the nesting beach by about one metre,” Dr Miles said.
“A comparison of that area to other, unmodified areas of the nesting beach over two years’ revealed extremely positive results for researchers involved in the Raine Island Recovery Project.
“Apart from the beach remaining stable, results show a higher nesting success with turtles spreading out across the re-shaped area rather than concentrating in confined spaces – which has resulted in fewer turtles digging up previously laid eggs.
“There has also been a reduction in stage one (early) deaths of eggs; a higher hatching success of eggs and hatchling production, and zero water inundation of nests,” Dr Miles said.
The Raine Island Recovery Project is a five-year, A$7.95 million collaboration between BHP Billiton, the Queensland Government, the Great Barrier Reef Marine Park Authority, the Wuthathi Nation and the Kemer Kemer Meriam Nation (Ugar, Mer, Erub) Traditional Owners and the Great Barrier Reef Foundation.
Raine Island is the nesting ground for about 60,000 green turtles every year.
Dr Miles said drone technology utilised during the 2015-2016 season helped researches track changes to the sand profile, as well as count turtles.
“The drones meant that topographic mapping was easier to obtain, and minimised any impact on the environment, helping preserve the sensitive ecology of this natural wonder,” he said.
“The drones have been highly accurate, and the results have shown that the re-profiled area of the beach has remained stable.
“The same technology will be used to continue monitoring so that the longer-term resilience of the changes can be determined”.
Great Barrier Reef Foundation Managing Director Anna Marsden said these early results were very encouraging and marked a positive start for the five-year project.
“Raine Island is such a special place which is of critical importance to the northern Great Barrier Reef’s endangered green turtle population, as well as the many other species that depend on it,” Ms Marsden said.
“Protecting the island’s precious ecosystem is a priority and the Raine Island Recovery Project is a working example of what can be achieved when we bring together government, business, Reef managers and traditional owners for the benefit of the Reef.”
Dr Miles said funding from BHP Billiton through the Great Barrier Reef Foundation meant the project team was able to have an increased site presence on Raine Island.
“This led to 40 adult female turtles being rescued and returned to the water during last season’s three field trips to the island,” he said.
“These turtles were likely to have otherwise died from heat exhaustion when becoming stranded or disoriented after the previous night’s nesting activity.
“Extra cliff top fencing was also installed, bringing the total to 1100m. The fencing prevents adult female turtles who have wandered into the centre of the island from falling off the cliff edges.
“These turtles had previously ended up on their backs after falling from the steep cliffs which have been created by erosion, leading to a terrible death without human intervention.
“We estimate that the fencing has prevented more than 400 deaths of adult female turtles since it was installed and this number will only continue to grow,” he said.
Dr Miles said preparations were well underway for the next nesting season, due to begin in November.