Any reports of a shark around southport (SA)

Took the kids out on the foamys today, once they'd had enough I couldn't help but take one out myself. While I was sitting out there something cruised under me, wasn't massive, dolphin size 6ft or so? First thought shark, then quickly thought nah, would've been a dolphin, kept looking for it come up, it didn't. Then it came back at a distance, water was clear but couldn't make out what it actually was. Looked intently to see it come up for air, but again I didn't see it. Thinking now I reckon it was a shark maybe a bronzey or a small white, maybe my mind playing tricks, but I am sure I saw a flash of a white on its belly as it went under me. Funny thing is I wasn't that freaked, probably the 150 other people sitting out with me. Any reports of sharks off the mid today?