If swimmers and surfers in Northern California needed a reminder of the dangers that lurk in the ocean, reports that the U.S. Coast Guard spotted 20 great white sharks near Pacifica should do it.
On Oct. 16, a Coast Guard flight crew patrolling an area that includes Pacifica Pier and Ocean State Beach in north San Francisco saw the 10- to 18-foot sharks swimming about 100 yards offshore, Coast Guard officials in Alameda County said.
While it's not unusual for the alpha-predators to be hunting in the area this time of year, this is the first time in recent memory so many were spotted at once, said Mary Jane Schramm, a spokeswoman for the Greater Farallones National Marine Sanctuary.
There's a reason this time of year is called "Sharktober Fest" in the Bay Area, she said.
The size of the sharks indicates it was mostly sub-adults and a scattering of a few "girthy," full-grown great whites, Schramm said. The older they are, the less likely they are to attack people because they've learned how to tell people apart from their sea lion prey, she said.
Still, "there are quite a few sharks in the area and the surfers, in general, are aware of that fact," she said.
Experts told her the sharks could be drawn to whale carcasses. The area is frequented by blue and sperm whales, and earlier this year, there was an unusual number of beached-whale sightings, she said.
Just two weeks ago, the first recording of a great white shark feeding in the waters off Alcatraz Island was posted online.
In the video shot by Meredith Coppolo Shindler, startled tourists waiting for a ferry gazed at the shark as it consumed the seal at the Alcatraz Island dock.
The 8- to 10-foot shark gulped the seal carcass just feet from the dock, said David McGuire, a research associate at the California Academy of Sciences.
A sea of red lingered above the water as the shark's fins appeared at the ocean surface.
In Southern California, experts say a possible record-breaking El Nino has been attracting dozens of sharks to the area as their food sources migrate to more tropical regions.