[FISH11]

My guess is if there were hundred, if not thousand, that it might be mating time in Southern California. So I Googled it and here's what came up..............
Bat rays reproduce on an annual cycle, usually copulating during the spring or summer of one year and then giving birth the following spring or summer. The male chooses his mate by following close behind her and assessing her reproductive condition by smelling her chemical signals.

Myliobatis californica: INFORMATION - ADWanimaldiversity.org › accounts › Myliobatis_californica ...................
"The male chooses his mate by following close behind her and assessing her reproductive condition by smelling her chemical signals."
.... Sound like a scene at a PB Bar!