Introduced in the 1800s as pack animals, the camel population was estimated at on million a few years ago but has fallen to 750,000, the Australian Feral Camel Management Project said.
The remaining camels now form the world's biggest wild animal herd, it said.
With few natural predators and vast areas with little human population in which to roam, feral camels have caused significant environmental damage, put pressure on native Australian species by reducing food sources and destroyed habitat, officials said.
In 2010 the Australian government endorsed a control plan, including culling, the BBC reported.
Since then, the camel numbers have been decreasing, officials said.
"Between 2001 and 2008, it was estimated that there could have been as many as a million feral camels in the outback," Jan Ferguson of the not-for-profit company Ninti One, which manages the AFCMP, said.
"Since then, however, there has been a major drought, the feral camel management program has come into effect and population survey techniques have been improved."
Camels roam freely across an area of 1.3 million square miles in the states of Western Australia, South Australia and Queensland, as well as the Northern Territory.