If swimming wasn't the first event, I'd like my odds. I don't like the idea of swimming at the same time as the shark, even if eating your opponent is grounds for disqualification.
Swimming is always the first event in a triathlon because asking someone to swim 2.5 miles after having run a marathon or cycles 100+ kilometers is an incredible recipe for drowning.
Just don't splash too much and the shark won't have any interest in eating you. If it does seem to want to come in for a nibble, hold your ground and forcefully push it down you when it comes close to check you out.