New research into native turtle populations in the River Murray has found some species were undetected in many locations across South Australia.
The study, by Western Sydney University, showed there was a drop in turtle abundances as the river approached the ocean – meaning there were little or no turtles caught at some locations.
Associate Professor of Ecology Ricky Spencer, from the School of Science and Health at Western Sydney University and a school-based member of Hawkesbury Institute for the Environment, said a decline in the species was foreseen over 30 years ago.
But due to funding limitations, political constraints, and limited data, the native species was at high risk of extinction.
"This is the first time research in the field takes such as deep and systematic look at turtle populations throughout the southern Murray River catchment, to identify likely hot spots of turtle declines and map geographic trends in turtle population," he said.
"Our research provides further evidence that freshwater turtle populations in southern Australia are rapidly declining.
"Even in areas where they are abundant, most populations have only older adults, resulting in few babies entering the river."
The broad-shelled turtle, eastern long-necked turtle and Murray River turtle were the three native species targeted in the research.
Associate Professor Spencer said the drought was increasing stress in some turtles, which was not good for the ecosystem.
"Turtles fulfil an important ecological role as scavengers of dead fish and the consequences of high mortality rates are significant for the health of the whole river ecosystem," he said.
"Australia deals with some unique factors leading to a decline in turtle population including introduced predators that ruthlessly destroy most nests each year, disease, road mortality and the fact that we are dry country and water resources have many competing demands."