Climate change is affecting freshwater turtle populations in NSW and is considered a very real threat, it was revealed at the Manning River Turtle Workshops in Wingham on June 6 and 7, 2019.
Mummified eggs, ground baked so hard that hatchlings could not dig their way out, and yolks in some eggs cooking before hatchlings emerge, have been reported by researchers working to conserve the endangered Bells turtle (also known as the Namoi River snapping turtle) on the northern tablelands.
We don't want to have the best documented extinction.Dr Arthur Georges
Locally, Phil Spark, an ecologist surveying the Manning River turtle, found long sections of the Barnard River completely dried up, with some turtle populations restricted to a few refuge holes. Dr Spark found those holes were overcrowded and had poor quality water issues. Turtles could be forced to move between pools which in turn increases the likelihood of predation by foxes, feral pigs and goannas.
Drought and climate change were named as the greatest threats to populations in the middle and upper catchments.
Other significant threats identified were predation, degradation of riparian zones (river banks) due to livestock grazing and weed invasion, interbreeding and competition with the Macquarie (Murray River) turtle, and the possibility of disease similar to the virus that decimated the Bellinger River turtle population.
Surveys of the Manning River turtle have been taking place over the last two years in a large area from the Nowendoc catchment in the north, Barnard in the west, Gloucester to the south, Elands and Bobin, and the Manning upstream of Wingham.
Two weeks ago the NSW Office of Environment and Heritage (OEH) released the results, with 86 sites surveyed and 293 turtles found at those sites. Some of those sites recorded healthy breeding populations, prompting OEH to call the results 'good news'.
However exciting the news of healthy breeding populations is, 293 turtles over two years is not a big number. Consider the Bellinger River turtle. Prior to the virus that wiped out 90 per cent of the population in 2015 the population of that turtle was estimated to be between 1600-4500 individuals. Currently the population of the Bellinger River turtle is estimated at 300 according to Ozgreen, and it is listed as critically endangered.
It was recognised at the workshops that more research still needs to be done - adding spring surveys to the autumn surveys, and looking at places that weren't widely research, such as the upper reaches of the Barrington, Gloucester and Bowman rivers.
However, some in attendance at the workshops urged that actions need to be taken now to mitigate risks that could cause further depletion of populations.
"We don't want to have the best documented extinction," said Dr Arthur Georges, who is studying turtle genetics, and for whom the Bellinger River turtle is named (Myuchelys georgesi).
Australian Reptile Park and Aussie Ark general manager Tim Faulkner agreed.
"We can research them to extinction. Something needs to be done now," he said.
Where are they found?
By far the most turtles were found in the Barnard survey sector in the Barnard, Little Manning and Pigna Barney rivers, not past 600 metres in altitude. The area is very rugged and poorly populated by people. A total of 200 turtles were found in 39 sites.
The Nowendoc sector included the Cells, Cooplacurripa, Mummel, Nowendoc and Rowleys rivers and 63 turtles were found from 38 sites.
The middle of the Manning River was surveyed from Bretti down to Wingham. Eight sites were surveyed and 24 turtles were found. However 81 Macquarie turtles were also found. Downstream from Wingham was not surveyed, as the water is brackish and the Manning River turtles require completely fresh water.
The Gloucester catchment (Barrington, Bowman, Cobark and Gloucester rivers) was not largely surveyed and only four turtles were found from four sites.
The Bobin, Bulga, Caparra, Cedar Party, Dingo and Killabakh creeks were surveyed from seven sites, and only two turtles were found.
While the numbers were perhaps better than expected in some spots, they are still low enough to cause real concern.
Where to from here
It's not all doom and gloom. On the Thursday afternoon ecologists studying the Bells and Bellinger River turtles shared what strategies were working to help save their respective turtles.
On the Friday the workshop participants split into working groups to begin to formulate plans for strategies for conserving the Manning River turtle.