Here’s an example of a Roman-era statue of Aphrodite, showing a dolphin eating a salmon:
http://www.digital-images.net/Images/GettyMuseum/Aphrodite_ofKnidos_RomanCopy_HS9141VLG.jpg
Aha!
Makes perfectly good sense now.
(All these years and I never noticed what was next to her.)
Maybe the rest of this statue is still on the sea bottom?