The surfer, whose name was not released, was attacked while paddling on his surfboard near Jensen Public Beach Thursday, TCPalm.com reported.
His left arm was bitten several times by a suspected 5- to 6-foot bull shark, said Capt. Emily Hall of Martin County Ocean Rescue.
The man sustained non-life-threatening injuries, Hall said. The beach was closed following the attack and reopened Friday.
Up the coast, two teenagers were bitten by sharks at a Volusia County beach Wednesday, the Orlando Sentinel reported, one of whom -- a 15-year-old girl -- required surgery.
"This is the time of year when we see more shark migration," Hall said. "It is not uncommon to see [sharks]. After all, it is their environment."