On Kangaroo Island, off the coast of South Australia, the devastating bushfire season of 2019-20 left behind an unlikely biosecurity opportunity. The fires wiped out an estimated 90% of the island’s feral pig population, which had been preying on newborn lambs, destroying grain and potato crops, muddying watercourses and severely disrupting the island’s unique native biodiversity.
After the fires, landholders and researchers moved quickly, using modelling to work out what it would take to remove the survivors before they could rebound. Three years later, Corey Bradshaw, the Matthew Flinders professor of global ecology at Flinders University, says: “We don’t have pigs any more, which is a world first in an area this large.”
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Professor Corey Bradshaw.
This rare eradication success offers a glimpse of what can be achieved when science, funding, collaboration and decisive action align.
It’s not just feral pigs that pose a threat: research by Bradshaw and colleagues published in 2021 found that invasive species cost Australia about $24.5bn a year, with total costs reaching at least $390bn in the preceding 60 years.
Invasive species had been a major factor in 60% of recorded global animal and plant extinctions, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services reported in 2023.
“It’s one of the top drivers of extinction and biodiversity loss globally,” Bradshaw says.
Through his research at Flinders University and on-the-ground work with organisations and government agencies across the globe, Bradshaw is showing how modelling can turn biosecurity into a predictive system. His findings, along with the work of others, helped estimate the cost, timeframe and resources needed to eradicate the remaining feral pigs on Kangaroo Island. He says a similar approach can be tailored to other biosecurity risks, from invasive weeds to wild deer.
“Without the models projecting what kind of effort is needed and how much it’s going to cost, it’s difficult to get the funding to proceed. Our bioeconomics research shows that the more you invest in controlling a species, and the earlier you can begin, the lower your long-term costs of damage will be.”
A collaborative approach to biosecurity
Through its current approach, “Australia is arguably a world leader in biosecurity”, Bradshaw says. “We are good at mitigating damages relative to the rest of the world.”
But he says the system is still fragmented across states and sectors, with “insufficient cross- or interstate collaboration on the bigger-scale issues. What’s considered a priority investment from the government in one state will be different to another, but invasive species don’t respect borders.”
He argues that this, together with a largely reactive approach that focuses on detecting and responding to threats after they appear, will need to evolve in the future, as factors such as climate change, global trade and environmental damage increase the number and complexity of threats.
“Climate change alone is going to make our current approach largely impotent because it’s vastly changing the distribution of threats like mosquitoes and bird flu. The expansion of species coming south from tropical regions in search of cooler climates is a huge potential risk that we haven’t really identified.”
To bring that broader approach together, Bradshaw and Flinders University are spearheading the creation of a new Australian biosecurity alliance, which will reframe biosecurity as a practical way to protect farms, ecosystems and public health before threats become bigger, more costly problems.
Rather than treating biosecurity as a set of separate agricultural, environmental or border-control problems, Bradshaw says the aim of the alliance is to connect experts – across fields such as climate science, First Nations ecology, and animal and plant health – with primary industries and government departments. They will explore new ways of working together and how best to future-proof efforts through targeted education and training the next generation of biosecurity specialists.
“This alliance is born from a two-pronged requirement: broader-scale assessment and intervention planning, as well as having more people specifically trained in the area with the appropriate skills,” Bradshaw says.
More data and better planning needed
Ultimately, Bradshaw wants to see a proactive approach to biosecurity, underpinned by more accurate data and better planning. For many established species in Australia, he says, researchers still cannot confidently calculate the benefit of reducing populations by a certain amount, and success is measured by the number of invasive plants or animals removed, rather than the damage avoided.
He shares the example of buffel grass, which has spread across Australia. It’s widely believed to increase the spread rate of fires, but there’s no data to back this up. “One of the most fundamental components in justifying why we need to control this species hasn’t been quantified meaningfully,” Bradshaw says.
This is where he sees the greatest promise for the emerging alliance. By bringing modelling, ecology and economics into the same conversation, governments and land managers can decide not only what to act on, but when and how hard, with science-backed action and a more connected national approach.
Bradshaw says getting the management of invasive species wrong could have serious repercussions. “At the end of the day, this is about saving money, saving native species and improving people’s health.”
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