I will second what Kevin said, but add that if The Great and Mighty Research Guru (aka me, Tasha the Triathlon Goddess, who apparently has so many gifts I could pass them around like cheap party favors) can't find evidence of anyone anywhere even spotting the barest glimpse of a shark in SF Bay............then they are not in the Bay. Period.
Now dolphins, maybe. But how cute and friendly are they?
So it has been spoken, so it shall be done.