Yes mate you do, unless you are exempt (check the web for details).
It will cost you $12 for a month or $30 for a year. All the money you pay goes into a trust that is spent on fishing, stocking, research, cleaning tables, habitat resto etc etc. One licence covers you for both fresh and salt water.
Hardly worth the rant really.
The alternative is don't buy one. If your checked by fisheries or the coppers you will be happily written out a $200 ticket. And that money doesn't go to any of the initiatives mentioned above.
Jas