Australasian Science: Australia's authority on science since 1938

Culling Won’t Save Devil

By Stephen Luntz

The decision to abandon a trial to cull diseased Tasmanian devils has been endorsed mathematically.

While the Forestier Peninsula is largely isolated from the rest of Tasmania, devil facial tumour disease has spread there. From 2004–10 the Peninsula was used as a test case investigating the viability of trapping devils and euthanising those with the disease.

However, the trial was abandoned and now Mr Nick Beeton of the University of Tasmania and Prof Hamish McCallum of Griffith University have confirmed that culling was never likely to work.

“Disease suppression can only work if you can catch enough of the infected animals in the population to make sure the disease won’t bounce back,” Beeton says. “For all the models we used, we found the removal rate required to suppress disease was higher than that which would be feasible in the field.”

Beeton says that if the program was going to work anywhere then the Peninsula would have been an ideal location, combining isolation with a high devil population. However, the culling program operated by catching devils and testing samples from those with obvious facial lesions. If a test capable of detecting the disease before it is visible becomes available the model may need reworking.

In the event that a vaccine or cure is anticipated, culling might be a viable way to slow the progress of the disease temporarily. However, McCallum notes: “Given the limited progress in developing vaccines against human cancers, despite huge investment in research, hoping a vaccine can be developed against DFTD seems optimistic”.

Insurance populations exist in zoos around the world, and Beeton says that “it is important also to establish disease-free wild-living populations on islands or in very large fenced landscapes”. None of the islands off the coast of Tasmania currently support devil populations, but Beeton says their creation could be crucial if the devil is to be reintroduced after the disease has burned itself out. “Devils on islands would have wild characteristics essential for reintroduction,” he says.

However, establishing such populations would require effort. “It’s not just a matter of putting them on the ferry and saying: ‘Good luck’.”