I have seen them at Twin Bridges in Fernvale and they were very helpful in helping us Freshwater novices understand a few rules and regs. No checking anything as we had not gone out yet. Apart from that I have seen either them or water police (not sure which) checking around the middle of Bribie Passage. Also have seen lots of small planes flying overhead around the passage which I'm told are connected to the Nat Parks/fisheries/waterpolice or some authority out there. Mates have said they have seen the planes fly by and then not long after a boat has come by and pinged people.