I've seen the same thing- could even be in the same spot. It was a tricky thing for me because I'm always down there often, at night, by myself. I made a call not to be confrontational, main reason being the offenders invariably pull out the race card... I've worked the prawn trawlers in the Strait and truthfully.. can see where they're coming from, at least.
I just cruised up, started having a yarn.. then quietly mentioned that 'some white kunzi' had bailed me up about the net and was calling DPI on his mobile. Net was packed away within 15 minutes.
I don't know about down South.. but up here there are really strong 'cultural' facets at work. Now I don't suggest that that exempts anyone from doing the 'right' thing. But I do make the point that, as far as recreational offenders go, there has to be a better approach than the authoritarian.
Heard of some good work being done in NT where monitoring/custodial roles were established for the locals. Would be great to see a similar program for indigenous urban youth...