Saltwater crocs tested for DNA to track movements

04-Mar-2019

CDU Outstanding Professor Sam Banks is mapping the genetic diversity and movement of crocodiles across northern Australia and southeast Asia

CDU Outstanding Professor Sam Banks is mapping the genetic diversity and movement of crocodiles across northern Australia and southeast Asia


Eighteen mature domestic and wild saltwater crocodiles in Timor-Leste have been sampled for DNA as part of a project determining the reptiles’ movement patterns.

Charles Darwin University Outstanding Professor Sam Banks said the project mapped the genetic diversity and movement of crocodiles across northern Australia and southeast Asia.

“Anecdotally, there are reports of crocodiles swimming in the middle of the Timor Sea,” he said. "Our research is determining the origin and movement patterns of the crocodiles through DNA sampling."

Professor Banks said while in Timor-Leste the research team took skin samples of several crocodiles ranging up to five metres in size.

“The crocodiles were big and healthy, with some kept as backyard pets,” he said.

“One local family own a four-metre saltie named ‘Maria’. They have had it for more than 35 years. Maria bellows when it’s hungry and fed chickens by the neighbours and family.”

Professor Banks said Timor-Leste was definitely ‘croc country’ much like the NT, but with its own distinctive flavour. They pose a risk, especially to traditional fishermen, but are also highly-valued in traditional culture.

“You wouldn’t expect to find many crocodiles in the centre of town, but Dili’s special police unit has three large salties in separate enclosures on their premises. Many of the crocs sampled were captive pets as well as wild animals around the coast and inland lakes.”

Professor Banks said he and his collaborators would extract DNA from the skin samples, which would be sequenced and the genomic information from the Timor-Leste crocodiles added to a growing database. The skin sample is taken from a special prong and is half a centimetre long and two millimetres wide.

“We already have approximately 700 samples, mostly from crocodiles in northern Australia, although we got a few from Singapore recently,” he said.

“The team is also working towards adding samples from other countries. Some from Papua New Guinea are in museums in Australia and we would love the project to include Indonesia and the Solomon Islands.”

Professor Banks said this information would go towards a genetic reference map of the saltwater crocodiles.

“This means we can use the DNA of a crocodile to find out where it was born and map the movement pathways of these giant predators around our coasts and rivers,” he said. “It will show their migratory habits or if they are unique to one location."

Professor Banks, a conservation biologist, is working closely on this project with the NT Government and will use this research in his work on crocodile management for conservation and human safety.

“There’s no reason to think crocodiles are bound by national or international borders,” he said. “This research will get us thinking about whether we need a regional approach towards managing these ancient beasts.”

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