The Ningaloo Reef, on Western Australia’s north-west coast, is one of the world’s turtle hotspots.
Six out of the seven species of the world’s sea turtles have been recorded there. Three of those call Ningaloo home all year round, while the others are occasional visitors.
That's because Ningaloo contains important feeding grounds and nesting beaches nestled behind Australia’s largest fringing coral reef, which extends along 300 kilometres of coastline.
In the second episode of our audio series, Ningaloo Outlook, we spoke with Senior Principal Research Scientist Dr Mat Vanderklift about the wonderful world of sea turtles and his research into their lives at Ningaloo Reef. Here are his top three facts about the turtles of Ningaloo.
1. Some species are more elusive than others
While six species of sea turtles can be found at Ningaloo, Mat said green turtles are the most abundant.
"There are only really three [species] you can see on any given day, and if we’re driving around in a boat and we see 100 turtles, 98 of them are going to be green turtles, one’s going to be a loggerhead and one’s going to be a hawksbill," Mat said.
One question we've not yet been able to answer is how many turtles there actually are at Ningaloo.
Mat and the team are trying to unravel this mystery using drones, which fly along pre-set survey routes taking photos of the sea underneath. Turtles must come to the surface to breathe and, when they do, they are visible in the photos. We can then work out the number of turtles in the area from the number that can be seen in the photos.
2. Turtles can travel over 1000 kilometres to nest at Ningaloo
"What we’ve discovered is there are turtles that live in Ningaloo and that’s home, they just live there, and they leave Ningaloo only to go and nest," Mat said.
But Ningaloo is also one of Australia’s important nesting areas. Turtles come from a very wide area of Western Australia to nest at Ningaloo. Using the satellite tags, the team has tracked nesting turtles from Ningaloo covering south to Shark Bay and north to the Kimberley.
"They’re coming from more than 1000 kilometres away to nest at Ningaloo. But the turtles that live at Ningaloo don’t tend to nest at Ningaloo. They leave, and they go and nest in the Pilbara," Mat said.
3. Turtles grow slowly
Ningaloo Outlook researchers have also attached flipper tags to more than 400 turtles at Ningaloo. By recapturing some of those individuals, Mat and the team have discovered new insights.
Some of these turtles have been particularly memorable.
"There are some really cool ones, like this one [see image above] we caught in 2017 in the water at Ningaloo," Mat said.
"Turns out that tag, when we traced it back, had been put on the turtle while it was nesting at Barrow Island in 1987, so that was 30 years earlier.
"It was already 97 centimetres when it was nesting, so it was an adult female when it was nesting. And then 30 years later we found it still living in Ningaloo. So it’s an old, old turtle. In 30 years, it grew 1.5 centimetres."
There’s also one unadventurous turtle the team have caught four times in the past eight years.
"It just lives in this one place at Ningaloo and when it hears the boat coming, it must groan and go, come on!" Mat said.
"It’s grown 4.5cm in 8 years, from 55cm to just about 60cm."
Ningaloo Outlook is a strategic marine research partnership between CSIRO and Woodside Energy.