A pilot flying out of Oceano County Airport on Tuesday evening reportedly saw at least 13 large sharks swimming in the three-mile stretch of ocean between Pier Avenue in Oceano and the Pismo Beach Pier, according to a California State Parks official.
The pilot took a few photos and reported what he saw to California State Parks rangers, who then posted warnings along Pismo State Beach on Wednesday.
California State Parks district superintendent Kevin Pearce said the sharks measured 5 to 12 feet long. Some were within the surf line, he said, while others were within a half mile of the shore.
A sign posted on a walkway piling at the end of West Grand Avenue in Grover Beach, near the entrance to the Oceano Dunes State Vehicular Recreation Area, warned beachgoers, "Enter the water at your own risk".
"There is nothing to be concerned about," California State Parks district superintendent Kevin Pearce said about the shark sightings. "There was no aggressive behavior witnessed or reported. They were just kind of doing their thing."
He was not able to identify the species of shark sighted.
"We just ask that people be smart in the water," Pearce said.
Pearce said reported shark sightings become more frequent in late spring to early summer.
Great white shark sightings have increased in recent years on the Central Coast outside of the late summer and early fall, the typical peak season for sharks, based on a number of factors including warmer waters and shifting hunting patterns.
The shark warning expires Friday.