The “in the field” research, finished only weeks ago, found 92 per cent of the endangered species were now in a “retirement home” and only 8 per cent were “teenagers” or young breeding turtles.

The "punk" turtle has made its way on the Zoological Society of London's Evolutionarily Distinct and Globally Endangered Reptiles list.

“It is like the living dead,” Charles Darwin University turtle researcher Marilyn Connell said.

“They are all getting older and older and very few of them are reproducing, so there is no one coming in for the next generation, or the next generation after that.

“Given our study, we wouldn’t be surprised to find there is a bit of a collapse in the population.”

Ms Connell said turtle researchers respected the “doggedness” of a turtle species that linked back to the age of dinosaurs.

“It’s such an ancient species that was hanging around when the dinosaurs were here and now potentially under our watch it might just disappear through our failure to act," she said.

Ms Connell’s CDU Mary River turtle study was the first sample large enough to be used as a baseline survey for the Mary River turtle.

It is the first rigorous field research on Mary River turtle since 2001 and 1998.

“The issue is they are much larger and older and the youngest class sizes are all missing compared to a 2001 study,” Ms Connell said.

“Our survey shows this young cohort is really in dire trouble,” she said.

“They made up only about 8 per cent of the turtles we captured in the river,” she said.

The three-year study found:

The critical groundwork and trapping of Queensland’s bum-breathing Mary River turtle was only completed at Easter.

Ms Connell says the major problem shown by her three-year survey of 480 turtles was there were very few young Mary River turtles and even fewer living until they could breed.

“We found very few that would be less than 15 to 20 years old; very few,” she said.

Young Mary River turtles are killed by cars and eaten by dogs, foxes and goannas on the river edge and by booming numbers of fork-tailed catfish and other competing fish species in the Mary River, she said.

Ms Connell, who was awarded Churchill Fellowship for her turtle research, said her team had collated results from 480 turtle trapping nights on the Mary River from 2015 until Easter.

She estimated there were 10,000 Mary River turtles in the river.

Mary River turtles are like humans and females become sexually mature and able to breed after they grow to 15 to 20 years of age.

They can live for about 100 years.

The endangered turtle was only discovered in 1990 by Sydney researcher John Cann.

It was yesterday identified as the world’s 30th most-endangered reptile by the prestigious Zoological Society of London (ZSL's) Evolutionarily Distinct and Globally Endangered (Edge) Reptiles list.

Ms Connell said her team measured the turtles' shells to understand their age.

The results will be published this year in several scientific journals.

Ms Connell said it was difficult in 2018 to say if the Mary River turtle population has increased or decreased.

“We don’t know that because no one has ever done a baseline study before,” Ms Connell said.

“We’ve done it with standardised procedures so someone in the future can come back and do a comparative study and actually say if the population is increasing or decreasing."

The endangered Mary River turtle is found only in the Mary River behind the Sunshine Coast.

It is not found in still water and needs water flowing over rocks to generate oxygen on the water surface because “it breathes through its bum”, she said.

“They tend to hang around the ripple zone in rivers, where there is a lot of oxygen."

Then-federal environment minister Peter Garrett rejected the Traveston Crossing Dam in 2009.