Traditional Navigation
I can't talk for all the indo boats coming in to oz waters but a while back I went out with aqis offshore to inspect a recently 'acquired' fishing boat that was found all the way down past Aurukun packed full of indo fishermen. The guy told me one of the first things confiscated was a gps. Probably not one of the 'traditional' navigation methods they'd want you to know about.
As for blox yes he should have done his paperwork but he certainly shouldn't be in jail.