YEP~
https://i.imgur.com/AOF0h5F.png
If you're usually hanging out in the water with your sim in the deeper part you may be lucky to see one. Earliest I've seen one is being in the water for about 2 sim hours longest about 4 to 5 sim hours.
There's also a dramatic chord of music when a shark does show up. It stills startles me. This is pretty much your only warning if you don't get your sim back to shore ASAP as it's a precursor to their demise. :#