Replacement Dash not seen in the vicinity either, unless there's another one launching from Darwin or Perth to cover their schedule's aswell and make sure our water's are not invaded
Try making an FOI request to find the truth. Those tasking are not as silly as you would expect.
Here is some open source reporting to put you in the ballpark:
Operation Relex II - Australian Border protection
This is the Australian Defence Force operation which contributes to the whole of government program to detect, intercept and deter vessels transporting unauthorised arrivals from entering Australia through the North-West maritime approaches.
Op RELEX II is currently based on a Task Group comprising one major fleet unit, an AP-3C Orion maritime patrol aircraft, Navy patrol boats and an army security element. A standby AP-3C Orion is available to deploy to provide a surge capability if required.
Operation Relex II includes units from all three services and supports Coastwatch and Customs.