Experts fear Australia has lost the battle against cane toads, saying the invasive pest species is here to stay.
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Instead of focusing on eradicating cane toads, a federal parliamentary committee has been told efforts should be focused on halting the spread of the toads to ecologically sensitive areas.
The House of Representatives Standing Committee on the Environment and Energy has been conducting an inquiry into control measures for cane toads and whether they need to be altered.
In a submission to the committee, the CSIRO said standard control measures - which ranged from toad-proof fencing to sending people into the field to pick up and remove toads - were not having a long-term effect on toad populations.
“Many of these measures are labour intensive and, while they can be effective at a local level, they are not able to contain toads at a landscape scale,” the CSIRO submitted.
“This indicates the need for new approaches aiming at the development of tools and strategies that can address the problem at a landscape scale.”
Suggestions from the CSIRO included introducing a virus to target the toads in the wild, and using gene-editing techniques to prevent the toads breeding.
The peak science body admitted some of the measures put forward were not ready for field testing, while others carried ethical implications.
Renowned evolutionary biologist and amphibian expert Professor Rick Shine submitted to the inquiry that much of the response to the spread of cane toads had been unfocused and ineffective.
“Control of toads over large areas where they already occur would have little benefit for biodiversity, and likely is impossible without resorting to methods (e.g., genetic manipulation) whose risks outweigh the benefits,” he wrote.
Professor Shine instead recommended targeting the front line of the toads’ spread, pointing to the example of the Sydney suburb of Taren Point, which used a combination of toad fences and hand-capture methods to eradicate a cane toad population that sprung up in 2018.
He warned against genetic manipulation methods, not only because of the risk that alterations could be transferred to native frogs but also the time and expense that would be required to develop it properly.
Professor Rob Capon from UQ’s Institute for Molecular Bioscience took a more measured approach, calling for action at the front line of the toad’s progress across the country and urging that control measures in areas where the toads were already established should not be given up.
“There is an urgent need to support action both at the invasion front (ie ‘out west’) and within invaded urban and rural areas (ie ‘back east’),” Professor Capon said.
He said in particular two methods - toad trapping and tadpole eradication - should be used in both scenarios as they had proved the most effective.
The main concern in the current fight against cane toads is their spread across wilderness areas of the Northern Territory and into northern WA.
WA’s Pilbara region is considered a front line in the battle against the toad’s spread, with several submissions made to the inquiry about how to use natural toad pathways like river systems to head them off.
Since being introduced in Queensland in 1935 in a misguided effort to combat the cane beetle, cane toads have relentlessly spread into NSW and the Northern Territory.
They secrete poison which makes them deadly to predators which would otherwise feed on them, and produce at a prodigious rate, with females laying between 10,000 and 30,000 eggs in a single clutch and breeding on average twice a year.
The inquiry is currently conducting public hearings on the issue, with the next to be held in Canberra on February 20.
