Turtle dreaming: a dive into our archives

As part of the Ultramarine project we are diving into our archives and republishing some paid content for free. This long read was originally published in issue 97 of Cosmos print magazine, in December 2022. You can read more amazing long reads if you subscribe now.

In a remote archipelago off Australia’s Top End, scientists and Indigenous rangers are collaborating to gather knowledge about the region’s large marine animals, which are thought to be in decline. Story and photography by DAVID HANCOCK.

In the warm, shallow waters that lap Australia’s Top End it’s called a “rodeo” manoeuvre; where someone leaps overboard from a boat that’s been following a turtle to grab and hold the marine creature. There is a real knack to catching a turtle this way, according to Kakadu ranger, Dwayne Wauchope.

“You have to get that technique right – where your hands go out automatically and grab him behind the head and tilt him up,” Wauchope says. “You have to make sure your hands are not close to any rocks or coral and you don’t grab him by the shell, because you can cut your hands.”

A ranger at Northern Territory’s Kakadu ­National Park for more than 20 years, Wauchope says members of his family from the Cobourg Peninsula, 350 kilometres north-east of Darwin, have been catching and harpooning turtles for generations.

“Your parents teach you from an early age,” he says. “Now we have boats and all that other high-tech stuff, I don’t allow harpooning. If you’re not a really good harpoon person, you can hit the turtle in the lung or elsewhere and if you don’t want the turtle and you let him go, he is likely to die.”

There’s increasing suggestion across northern Australia among Indigenous coastal communities that turtle and dugong populations are declining. At Elcho Island, traditional Yolngu owners have asked hunters to limit their take.

“We still eat turtle and dugong because it is better than food from the store,” says David Ganambarr, a traditional owner of the Wessel Islands, which stretch north from Elcho into the Arafura Sea. “When we go out and hunt dugong and turtle, we tell everyone they can only take two turtles at one time, and with dugong – only one. If there is a funeral they can take more because we have to feed everyone ­involved.”

Western science is sympathetic to the concerns of coastal Aboriginal people. Scientists believe climate change, rising sea levels, high temperatures, marine debris, commercial fishing, feral animals and even lights from industrial and residential developments play a growing role in declining numbers of marine megafauna. According to Charles Darwin ­University marine biologist, Dr Carol Palmer, it’s incorrect to assume – as some do – that the decline is down to traditional hunting.

Based in Darwin, Palmer is heading up an Australian Research Council (ARC) project that brings together land and sea rangers, traditional owners, s­cientists, universities and government. It’s a landmark partnership that links traditional marine knowledge with Western science. The aim is to establish standardised protocols for monitoring marine megafauna; to identify densities of key dolphin and sea turtle populations by recording sightings and gathering DNA samples; and to identify key habitat areas for conservation management using satellite tracking and traditional knowledge.

The project focuses on four threatened species of cultural importance: the endemic Australian snubfin (Orcaella heinsohni) and Australian humpback (Sousa sahulensis) dolphins, and green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles. Other species of dolphins and turtles – along with whales, dugongs and manta rays – are being recorded and DNA sampled (if possible) during the three-year project which began last year. It’s an enormous venture that ranges from the Wessel Islands in the east west to the Darwin region, and includes more than a thousand kilometres of coastal and adjacent sea country.

Indigenous groups involved include the Larrakia rangers from Darwin, Gumurr Marthakal rangers based at Galiwin’ku on Elcho Island and rangers from Kakadu NP and Cobourg Marine Park. Palmer says Aboriginal people have noticed impacts on coastal and sea country that their parents, grandparents and great grandparents have traditionally managed and woven stories around.

“Having worked with ranger groups across the NT and the Kimberley for many years I know their information about plants, animals, weather and hotspot areas on the land and sea is so crucial to our understanding of northern Australia,” she says.

“It’s important to acknowledge that and to record it and make it publicly available. Important because most Australians don’t realise how expansive and precise their generational knowledge is and it will definitely help us manage Australia’s amazing marine megafauna.”

Aboriginal people, too, are keen to exchange knowledge.

“We are noticing the numbers [of many species] are dropping because we are out there all the time,” says Wauchope, who works in the South Alligator region of Kakadu.

“If we are not at sea while we are at work, then we are out at sea after work, or on holidays. When someone asks us [about our local environment] we know what we are talking about.

“Working with Carol I am learning so much more about turtles, dolphins and other marine animals. Collaboration with scientists helps me out and it helps our people when we go to meetings [with government decision-makers]; we know exactly what we are talking about and are aware of many of the things that they try to tell us. As Indigenous people, where we lack a little bit of scientific knowledge in those finer things such as life cycle and genetics, we do know a lot about these animals from daily experience and what has been handed down by our ancestors.

“There are a few things I have found very useful, for example we learn about sea grass and habitat and realise it’s a wider thing, not just about the turtle. We walk around back home on the sand and Carol is telling us about the grasses and things, so we see what she is talking about. Yeah … science and traditional knowledge – it’s like a missing puzzle.”

Knowledge shared – and multiplied

The Wessel Archipelago is a narrow strip of islands extending north-east of Galiwin’ku community on Elcho Island, for about 120 kilometres. The most northerly point is Cape Wessel, which houses a beacon to help sailors who ply the route from Gove to Darwin. The islands are low and sandy, with mangroves and heathland and have outflows of springwater. More than 55km long and around eight kilometres wide, Marchinbar is the largest island in the group.

On the western – or leeward – side, the beaches are long, flat stretches of pure white sand; coral is common and sea creatures abound. On the windward, or eastern, side, sheer cliffs rise up to 60 metres from the sea; between some of the cliffs are small secluded bays that attract nesting turtles. The islands are also home to saltwater crocodiles and it is not unusual to see their tracks circling nesting sites. The islands follow the Top End wet/dry climatic seasons and, early in the year, waterfalls cascade over the cliffs from monsoonal rain.

It’s an enormous venture that ranges from the Wessel Islands in the east west to the Darwin region, and includes more than 1000km of coastal and adjacent sea country.

If the sea is smooth and undisturbed it takes about three hours to travel from Galiwin’ku to Hopeful Bay on the western side and southern end of Marchinbar Island by open boat. If a swell from the north is running it can be a laborious, drenching, hull-slapping journey that takes up to five hours. Not only are the Wessels a hotspot for nesting green, hawksbill and flatback turtles, but Marchinbar Island is home to rare terrestrial species such as the golden bandicoot (Isoodon auratus) and northern quoll (Dasyurus hallucatus). Unlike the mainland, there are no feral animals or plants on the Wessels, making the archipelago an ideal environment for scientific research.

The islands are currently uninhabited, but they were home to Yolngu Aboriginal people for thousands of years. The islands were mapped and named by Dutch seafarers in the 1600s and frequented by Macassan traders, who collected trepang from the shallows of sandy beaches and coral reefs.

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Turtle futures

Northern Territory waters are graced by six of the world’s seven marine turtle species – green (Chelonia mydas), olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea), flatback (Natator depressus), and loggerhead (Caretta caretta).

Marine biologist Carol Palmer (right) has been studying them and other Top End marine megafauna for decades – and she doesn’t like the look of the future.

“Certainly traditional owners and rangers are worried about the numbers of turtles and green turtles in particular,” she says.

Palmer thinks the population reductions are probably down to some clear changes. “Definitely, sea level rise, and sea temperature rise.”

She says more and more rangers in these remote locations are talking about sea level rise.

“It was their parents or their grandparents or their great-grandparents who know these areas,” she says. “And we could be just talking about small little islands, or many of the beaches.

“But also the temp rise with the nesting turtles. This is coming out more and more certainly… for the green turtles, which is what we’re focusing on, and the hawksbills.

“The temperature is really, really increasing here in the Northern Territory, and that means that of the eggs that hatch, 99% are going to be female and 1% male.”

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During World War II the Australian Government set up observation posts at Cape Wessel and at other places on the islands. In 1943, a minesweeper, the Patricia Cam, was attacked and sunk by a Japanese float plane; several naval crew members and Aboriginal pilots made it ashore and were rescued.

In 1944, nine coins were discovered south of Jensen Bay on Marchinbar Island. Four were identified as Dutch, minted between 1690 to 1780; five with Arabic inscriptions originally came from the Sultanate of Kilwa in east Africa and were created sometime between the 10th and 14th centuries. No-one knows how they got there.

Carol Palmer began working at Marchinbar in the 1990s, researching the golden bandicoot population – the species was close to extinction on the mainland. The relationship Palmer developed with traditional owners and Indigenous rangers enabled her and other scientists to establish the ARC project at Hopeful Bay in 2021.

“I think the Wessels is a unique archipelago,” she says. “It is certainly a hotspot for dolphins, some whales, manta rays and, in the past, it has been a well-known area for green turtles. But last year when we did our first survey there, and this year, the turtle numbers were very, very low.

“We did catch one large female and put a satellite tag on her and we monitor where she is going every day. She is still in the area but moving quite a way out. However, marine megafauna is not just turtles, this is a multi-species project.

“The other part of the project is an exchange between ranger groups. Kakadu rangers came to the archipelago last year and again this year. Dwayne Wauchope and Puna Cooper shared knowledge from Kakadu, with Gumurr Marthakal rangers. Their expertise and understanding about how to do a lot of this work is really substantial. All the rangers have emphasised to us how important the ranger exchange is and it’s the recording of not just western science but the traditional science from different areas.”

“Their information about plants, animals, weather and hotspot areas on the land and sea is so crucial to our understanding … Most Australians don’t realise how expansive and precise their generational knowledge is”

Wauchope and Cooper say the exchange of knowledge has been eye-opening.

“The Marthakal mob have got stories that are nearly exactly the same as our stories and yet we live so far away from them – the stories are a little bit different in the details but very similar,” Wauchope says. “We learn when they hunt, how they hunt, how they call country; it is good for us.

“I have been in Kakadu so long and that is what we are missing, that exchange of knowledge – it just makes you into a better person and a better ranger as well, and it is reassuring to know they are having the same struggles we have.”

An ocean of waste

As pristine as it is, the Wessel Archipelago faces major problems, foremost among them marine debris.

“I started work on Marchinbar with golden bandicoots in the 1990s and worked through to 2011,” Palmer says. “There was virtually no plastics or ghost nets during that time. In 2016 we went back to check the bandicoots and we noticed the amount of ghost nets and plastics had increased substantially. In 2021 it had increased even more substantially. I had never seen so many plastics and ghost nets across the NT.”

Dr Scott Whiting, Principal Research Scientist, Marine Science, with the Western Australia Department of Biodiversity, Conservation and Attractions, accompanied Palmer to the Wessels this year. He says the incidence of marine debris from the western side of the Gulf of Carpentaria all the way to Cobourg Peninsular probably ranks as some of the world’s worst.

There are turtle nesting beaches littered with plastics and the remains of fishing nets. At sea, discarded nylon nets tangle to form their own eco­systems that float and follow currents; they trap, injure and kill all kinds of marine animals. These ghost nets can reach down for metres and trail for hundreds of metres, and can entangle marine creatures for years.

The Plastic Soup Foundation, an inte­rnational body dedicated to raising awareness and fighting plastics pollution at sea, claims hundreds of millions of marine animals annually are killed or injured by ghost nets.

“The Marthakal mob have got stories that are nearly exactly the same as our stories and yet we live so far away from them. We learn when they hunt, how they hunt, how they call country; it’s good for us.”

“Marine debris is fairly invisible to us until it washes ashore,” Whiting says. “It affects turtles when they are very small when we don’t see them – so it is not the turtles here in the shallows that are affected by marine debris. It is the turtles being killed out there at sea. We probably don’t know what we are missing, because they don’t end up arriving.

“We do see all the life stages of species caught in marine debris, in the nets, because they are foraging on the surface of the ocean and those nets provide a micro habitat. Because they are searching for food on the surface, they will eat all the bits of plastic floating along. That is a really big issue and a problem that is as much a foreign affairs issue as a conservation issue because it’s ubiquitous around the world. It just can’t be solved easily and it will take many decades to reduce the pressure.”

Much of the debris in Australian waters and on our beaches comes from neighbours to the north; most of it is swept into the Gulf of Carpentaria, across the Top End and out into the Indian Ocean. It deeply concerns traditional owners, because their ability to manage the problem has gone beyond the scope of many communities. Even though coastal ranger groups regularly collect plastic debris along beaches, most ghost nets are too heavy to deal with – it’s been suggested the Royal Australian Navy use their vessels to tow the nets ashore to be destroyed.

Marine debris might be the current issue that’s challenging their capacity, but Indigenous ranger groups play a major role in marine management right across northern Australia, from Cape York to Broome.

“Overall, it has to be the most positive movement I have seen for Indigenous social outcomes in terms of education, health, youth justice and conservation,” Whiting says. “Here is a pathway where kids can see where they could end up, and their role models are probably one of the biggest benefits I have seen.

“I think putting funds into them now is a miniscule amount than if government had to do it in ­another way. Many communities struggle to find an industry to support themselves but I think we have already got the industry – land and sea management across Australia that is done by people who want to be here and have ownership in the area and are going to be here for generations.”

Alliances between scientists, traditional owners and Indigenous rangers are only going to strengthen over time. “Hopefully this research program will be able to develop a proper on-ground working program for all the sea ranger groups in their traditional sea country,” Palmer says.

“It will probably be different in many cases and will not be like having one policy that will cover everything … that will not work. The more remote things are, the more difficult and expensive management becomes; to have one year’s funding will not work.

“What we need is long-term funding for management of marine megafauna and to help step rangers, traditional owners and kids through the process.”