There is a considerably complicated discourse when it comes to Australians and their native people and quite often the official narrative has been changed and adopted by different politicians for their own means.

Keith Windschuttle is probably one of the most prominent of the conservative historians who has often played down the atrocities committed against the aboriginal people. Windschuttle became a favourite of former Prime Minister John Howard during his time in power to forward his own agenda. Howard rejected the 'black armband' view of history and wanted to instill a more proud, patriotic and ultimately white Australian historical narrative.

Stuart McIntyre, another historian, heavily objected to Windschuttle's methods and this started what was called "The History Wars" in Australia which debated the severity of the force or violence used against the aboriginal people. If you also have a look at the page I linked to it does mention a little bit about genocide and it comes with quite a few citations.

The genocide debate revolves around the numbers and the official documents used. People like Windschuttle, a historical empiricist, would say that as there is no documented data of these supposed genocides, then there are no genocides. I suppose the key here, is that the reason much of the discussion about genocide has to do with a lack of contemporary documentation about it. The ambiguous nature of the wording of these documents too make it hard to make the final rule on a genocide.

I'll wait for more expertise, but you should have a look at Stuart McIntyre's "The History Wars" as a good starting point on the aboriginal history debate. I also would recommend Jonathan Richard's "The Secret War: A history of Queensland's Native Police" as some interesting books to read more about this topic.