Often referred to as species triage, it's a controversial approach that means picking which threatened animals will live and which will be left to struggle on unassisted.

Australia's first threatened species commissioner, Gregory Andrews, a former diplomat and an economist by training, took up his post in July.

Among the tasks to be tackled in his first year is to prioritise the country's threatened species, nominating those most likely to benefit from intervention. Ultimately the animals deemed a priority should be secured in the wild for at least the next century.

It's a contentious approach that takes into account how critically endangered an animal is, how iconic it is or how taxonomically unique a species is.

"Another [criterion to consider] is how viable is investing in its recovery ... some species cost more than others," Mr Andrews said.

More than 350 animals are listed as threatened by the federal government, including the southern corroboree frog, eastern barred bandicoot and southern cassowary.

While millions of dollars are spent on trying to reverse the decline of Australia's threatened species, the wins are few.

"We have 63 threatened mammals and 59 of them are flatlining or going down," Mr Andrews said.

Under chief executive Jenny Gray, Zoos Victoria has nominated 20 species it will concentrate its conservation budget upon, among them the Tasmanian devil.

The incurable devil facial tumour disease has destroyed 50 per cent of the population across two-thirds of Tasmania. There is no known cure or vaccine. Wild devil numbers have continued to slide as the disease spreads across the island.

Despite little return on a significant federal investment of more than $13 million since 2008, Mr Andrews also nominated the Tasmanian devil as a priority species.

Unlike other threatened species such as the critically endangered Baw Baw frog, however, the devil has status in the public's eye and in its own ecosystem, where it plays a key role as a top-order predator.

The economic rationalist approach to conserving threatened animals has also been adopted in New Zealand, where 700 species were identified as in decline and 300 of them prioritised as most likely to benefit from intervention.

Mr Andrews said the stance had allowed the country to work with 2.7 times as many threatened species as it was before it started prioritising.

"Some people may argue that it's an excuse to not spend money, but we are prioritising in a de facto way now," he said.

Prioritising the country's threatened species in order to better inform funding allocation was among the recommendations made in a 2013 Senate report, which looked at the effectiveness of threatened species and ecological communities' protection.

But not everyone is a fan. The independent, non-profit Australian Wildlife Conservancy says that if funds are invested correctly then everything can be saved.

The Australasian Bat Society believes choosing which species to save should never be an option - no one has a right to play God.

In Good Weekend: Playing God