Not so much a case of having big brassies, more just a case of a) having mentally prepared myself for it prior (thats why I approached it) and b) not having to be caught by surprise by it - I saw it before it saw me. I knew what I was getting myself into... kinda...
Sharks are not as common here as that clip might elucidate, or media might suggest. This incident occurred in shark bay Nth NSW, a known hot spot. It's not the only one I've seen there and no doubt there will be more. But before living here, I'd done almost 10km on the water on the east coast without a shark shield, without ever having had an incident. They are certainly not mandatory for yak fishing aussie open waters, but they are handy to have, for peace of mind if not anything else.
I've also used them to good effect stopping smaller sharks from stealing fish I;ve wound in. The video below includes an experiment where I get a hooked shark up close to the yak and then switch the shield on to see what happens. Enjoy
[youtube]http://www.youtube.com/watch?v=7O13Hf6KFQk[/youtube]