A collaborative research program could help change the management of Queensland's estuarine crocodiles and help improve public safety in Croc Country.
The Department of Environment, Science and Innovation (DESI) is funding the project in collaboration with the University of Canberra (UC), a leader in Environmental DNA (eDNA) research and accredited by the National Association of Testing Authorities Australia.
Researchers from UC have mapped regions of the estuarine crocodile's mitochondrial DNA using samples collected from animals throughout Queensland, Western Australia and the Northern Territory.
They have then used the research to develop a technique that can specifically detect minute amounts of a crocodile's mitochondrial DNA in water samples.
UC researchers Dr Peta Hill and Dr Elise Furlan said eDNA surveys rely on detecting a species from trace amounts of DNA shed into the environment through sloughed skin cells, faeces or urine.
"We conducted trials to detect DNA in water samples collected from crocodile holding ponds at the DESI facility in Cairns, and compared them with control samples of water," Dr Hill said.
"We will use these trials to confirm estuarine crocodiles having been present in those ponds."
"Once the crocodile is removed from the pond, water samples will continue to be collected to investigate DNA degradation over time," Dr Furlan said.
DESI Program Coordinator Simon Booth said wildlife officers from the Queensland Parks and Wildlife Service (QPWS) hope the eDNA research will provide wildlife officers with a valuable technique for detecting crocodiles in waterways without having to see them.
"Occasionally, wildlife officers respond to a crocodile sighting report and our conventional methods such as land or vessel-based surveys don't confirm the presence of a crocodile," Mr Booth said.
"This program is in the preliminary phase, but if the research program is successful, wildlife officers could take water samples to detect crocodiles in waterways that are hard to access, or areas the public use regularly such as swimming holes.
"We're hoping the research project will allow us to reliably test water samples to detect the presence of crocodiles.
"Investigations into the eDNA detection are expected to continue for the next 12 months, but initial results are promising.
"Captive trials are now underway at the DESI facility to analyse how long a crocodile has to be present in a body of water until we can detect it, and how long after it has left do we continue detect its DNA.
"Once we understand the captive dynamic, we will undertake sampling in rivers and other waterbodies around North Queensland, known to hold estuarine crocodiles to analyse DNA detection rates in these environments.
"People are responsible for their own safety in Croc Country, but eDNA testing could assist us in safely managing crocodiles in Queensland and across the country.
