Sorry, I don't agree.
It has way more to do with paying commuters slipping on fish guts and making a huge public liability claim. Also, I assume that the loss making Sydney ferries would prefer to not have to pay someone to clean up their wharves. Then there is the night time anglers who piss on til all hours and make too much noise.
Have to agree with Puppydawg. If there isn't anybody policing these issues now, who will police the bans?