I'm thinking the increased number of incidents in Sydney actually have a lot to do with a number of suggestions that have been made above.
The water quality around Sydney has definitely improved. At the moment, with warm water temperatures around 23 to 24 degrees C, there is a lot of fish, both schooling and pelagic around, and as we know, if you have schooling fish, you usually have feeding sharks, (just look at the sardine run in Africa).
Maybe the 3 attacks are just coincidence. Who knows?
While any attack is bad, we must remind ourselves that there has not been a fatality.
My main concern is the irresponsible and ill informed response by the media. We had one bald headed idiot host of a morning news show suggest we start wiping out all sharks around Sydney. We certainly don't need that sort of knee jerk reaction.
I don't know what it is about a shark attack that gets the press in such a frenzy. Maybe it goes back to all the hype that surrounded the movie "JAWS" all those years ago.
We have had unfortunate children that have been killed by dogs, sometimes the family pet gone bad, and the press never go as crazy on that sort of incident. Have a shark attack, and all hell breaks loose.
Hopefully, one day we will have responsible journalists who will report the facts , and not sensationalize the incident to sell more papers or improve TV ratings, though I won't hold my breath (I think I just answered my own question).
Cheers
Parso