[goinsfishin]

I doubt that you saw Mayworms on the surface.......the mayworm "hatch" is actually not a hatch at all, it's the mature males and females coming up out of the mud and moving around to mate......they will be right on the bottom in anywhere from 5 to 30 feet of water....and they are easy pickings for hungry, lazy rockfish.....this should start taking place within the next week or 2.....and lasts about 2-3 weeks.

I suspect that what your buddy saw were probably newly hatched snakes......with some species there can be 100's from a single nest.....
thankfully the mortality rate for snakes is real high or we'd be overrun.