Aerial surveys of green turtle nests showed a decline in nesting sites on Croker Island since the 1990s which has prompted further study of a range of species, a Charles Darwin University researcher has said.

The research is looking to identify foraging and migratory routes of turtles, whales, and dolphins in the Arafura marine park, and the sea around Croker Island, CDU’s Research Institute for the Environment and Livelihoods senior research associate Dr Carol Palmer said.

Dr Palmer said the research was the first of its kind in the Northern Territory, and was funded by the federal government in a collaboration between the university, the World Wildlife Fund, and Garngi and Mardbalk rangers.

“We are a hotspot for foraging turtles, dolphins, humpback whales, Bryde’s whales, and little spinner dolphins. It’s really amazing,” Dr Palmer said.

“But we’re still very much at the bottom of the pile here in northern Australia because the research is challenging and costly due to the remoteness of the region.

“This type of research has already been conducted on the east and west coasts of Australia, and our ecosystems here are just as important.”

Dr Palmer said the difficulty and cost of access was why aerial surveys had been used in the past to assess the condition of ecosystems.

RIEL PhD candidate Natalie Robson said her thesis was based on the foraging ecology of green turtles in the Northern Territory, and said rangers had serious concerns for the species’ future.

“Recently, we compared an aerial survey from the 1990s to one we conducted on the same beach this year and found a 78 per cent reduction in green turtle nesting,” Ms Robson said.

“A lot of these species are protected and play an important role in the Australian ecosystem, as well as culturally for First Nations people as a source of food.

“Only one in 1,000 hatchlings make it to adulthood, and an increase in sand temperatures has meant a reduction in male numbers – from our work in the NT foraging areas, we’ve found the proportion of adults to be about 71 per cent female compared to 20 per cent male.

“This research will help establish a baseline for sex ratios in our reefs, as well as age classes and mating success, so we can determine what measures are needed to ensure the effective conservation of these animals.”

Northern Land Council chair Matthew Ryan said the collaboration with CDU enabled the rangers to develop new skills so they could better protect the environment.

“The rangers are able to use their cultural knowledge to assist in scientific research, and develop strategies to reduce the feminisation of turtles and protect the eggs from predators such as goannas and feral pigs,” Mr Ryan said.

“While they have previously teamed up with CDU scientists, this is the first time their valuable contribution has been acknowledged through a formal funding arrangement – and already the project is paying dividends.”