Culling crocodiles is an ineffective and expensive way to reduce attacks on humans, new research has found.
Research published in the journal People and Nature found 91% of crocodile attack victims in the Northern Territory were locals, with human complacency and water-based activities contributing factors.
Between 1979 and 2022 there were 76 crocodile attacks in the NT, of which 23 were fatal. Most victims were male, and attacks primarily occurred when people ignored safety advice or were in or near water.
The study’s lead author, Dr Cameron Baker from Charles Darwin University, said it “highlights the importance of modifying human behaviour” in reducing the risk of attacks.
Researchers analysed nearly 50 years of data, a period in which the estuarine – or saltwater – crocodile population expanded from a few thousand individuals to more than 100,000.
The analysis revealed a “Be Crocwise” education campaign and relocation of problem reptiles had contributed to stabilising and reducing the frequency of attacks since 2009, despite increases in the density of crocodile and human populations.
The researchers said though crocodile attacks on humans often provoked calls for widespread culling, there was little evidence to support the measure , which was “not an effective and cost-efficient control strategy”.
Modelling based on the data showed that to reduce the frequency of attacks by one a year, culling would need to remove 90% of the crocodile population. Baker said this approach would “push the species back into the critically endangered category” and could cost close to $87.8m.
Charles Darwin University’s Prof Hamish Campbell, who led the study, said it was critical that crocodile management was evidence-based.
“The funds available for crocodile management are limited, and we need to spend these in the most effective manner to reduce crocodile attacks upon humans,” he said. “The evidence shows that widespread culling is not a cost-effective nor efficient means of doing this.”
Crocodile policy became an issue at the recent NT election, according to the ABC, with a new crocodile management program tightening the rules for people wanting to own pet crocodiles.
The management program, launched in April, sought to maintain the keystone predator species at appropriate densities and enhance public safety, while acknowledging “it is an apex predator that will attack humans and its coexistence with people presents significant challenges for the NT community”.
Dr Elise Furlan, a University of Canberra researcher not involved with the study, has developed a DNA test that could detect the presence of crocodiles in waterways, through research funded by the Queensland government. She said having better data could help. “If we’re able to detect where crocodiles are, people can obviously change their behaviour accordingly,” she said.
The sensitive DNA water test could offer another tool for preventing encounters with the “cryptic species”, in addition to visual surveys from land or by boat, she said.
“[They] can be hidden underwater and in murky waters. They’re an ambush predator, so they are very good at keeping very still and quiet.”
Dr Vinay Udyawer, a researcher from the Australian Institute of Marine Science who assisted with the study, said the results could be expanded to other large predators such as sharks.
“It highlights the general ineffectiveness of culling as a primary mitigation tool and the importance of alternative strategies like public education campaigns,” he said.
