I regularly kite in a North Queensland rivermouth and it's not uncommon to see sharks. Mostly it's not possible to see enough of the shark to identify it, as by default it is windy when I'm on the water and hence the water is turbid. Having said that, I'm more concerned about bull sharks than the others.
On one occasion I was happily mowing the lawn across the river and heard a load 'slap' behind me (it sounded like someone had whacked the flat face of a cricket bat on the water). I looked around in time to see the dorsal fin and thrashing tail of a shark. I'm guessing that I disturbed it as I kited over it and it tail slapped the water as it took off.
I've also had a shark surface in front of me, it was travelling across my line of travel and I just kept the same line and ended up kiting through the gap between the dorsal fin and tail.
We share the ocean we sharks (and crocs), that is how it is.
Most people like to think that they are at the top of the food chain and get a little unsettled when this idea is challenged. If you are going to kite (or do any other activity) in the ocean, accept that there is a risk, modify your behaviour if needed to lower the risk (you won't find me kiting in the Daintree) and enjoy your day on the water.
We are here for a short time and often worry about the wrong things.
For the record, I don't expect anyone else (council, government etc) to make the water safe for me. If I get munched by a shark or croc I'll accept that is just the nature of the beast.