Yep the bulls are around all right and they love the murky water.
Have to agree with DJ that they are probably more wary of us than we of them. I often see bull sharks in the river and canals around Noosa and people swim there all the time, hasn't been a bite yet.
I reckon that if there is plenty of feed around they won't be interested in us. Enjoy your paddling in the HackingRiver it is a lovely spot.
Cheers
ET.