FF,
Without knowing which beach you're looking at it's hard to say. There are a few places to get the info though by calling the lifeguards. A good all around place to start is
www.usc.edu/org/seagrant/beach/beach2.html They have the various beaches tagged out from San Clemente up North to Seal Beach. A few calls should get you in the ball park. At the DFG, there is a page at
www.dfg.ca.gov/Mrd/gruschd.html that lists the runs etc...They also have a grunion program of some type at Cabrillo Beach a few nights and have the contact # for that also.
Hows the fishing been?? I'm heading out tomorrow for some much needed RnR.
Hope this helps,
Perry