Sharks are a common topic among watergoers in Northern California. 
This is because the red triangle is here - Ano Nuevo, the
Farallons, and Tomales Bay. The first two are elephant seal
island colonies, and the third is a shark breeding ground. Here are some
things to know about sharks in the Bay Area. 

Sharks in the Bay Area that threaten surfers are Great White sharks. 

Sharks follow large pinnipeds around (mainly elephant seals).

There are 3 shark attacks per year in Northern California, with
a 7% fatality rate per attack (averaged since 1990).

There are millions and millions of man-hours of exposure in
Northern California.

The vast majority of the shark attacks occur during the salmon 
run from August 1 to mid September. The large pinnipeds may be
following the salmon close to shore.

According to Bob Wise, there has never been a shark attack at
Ocean Beach. I think the same is true of Linda Mar. There are
always lots of shark sightings on the south facing Marin coast,
and also north of Tomales Bay's mouth.

Shark attacks consist of the shark biting and mauling the victim, and
then leaving. Sharks don't like us skinny mammals. The largest damage 
that occurs is due to blood loss - often fatal. If you see someone
getting attacked PLEASE PLEASE help out. The shark is most likely 
gone, and the person needs to get out of the water and stop the
bleeding. 

If you choose to surf in a remote area in shark season, surfing with
a friend might be a good idea.