There were two catagories of grunion catchers back in the days that Michael and I are speaking of. First there were some serious catchers... Mainly Asians and Latinos back in those days. They did all sorts of exotic things with those fish (We heard rumors and stories!!) but we never saw them other than the skillets on the fires on the Beach.
The second catagory were the 'Beach Party' group. This was in the days before heavy drinking and drugs were an issue among the majority of the kids (Think of the Gidget group). We would build a fire in a fire pit and wait out the tide change for the fish to come in. We would go down the Beach (Seal Beach was a typical location) away from the fire pit area to a darker section and 'catch Grunion' when they came in. We also used that time in the darker section to exchange foolish promises of permanent love with our partner for the evening.
Since the Grunion only spawn a few nights each year, "Going Grunion Hunting" was a very special event. Newspapers would list the nights of the activity and the estimated arrival times on various beach locations. Sometimes there would be large crowds at the Beach early on, but most folks went home at MidNite or so..the serious members of both catagories made a night of it!!