It's summer time in Southern California, and that means the grunion run is on.

Grunions are those small sardine-size fish that come on shore to lay their eggs on sandy beaches. One of the best places to find them is Cabrillo beach in South Los Angeles, and the most recent run was just last night.

"The fish like to come out a couple days after the full moon because they want their eggs to not be disturbed by waves," researcher Dwight Causey at the Cabrillo Marine Aquarium told Take Two. "[The tide] mixes up the sand and that causes the release of the eggs into the water."

But big crowds can disturb the fish from landing, says Causey.

"Our research shows the vibration on the sand from people walking or shuffling around, they can feel and they don't necessarily like, and then all the lights can scare them away," says Causey.

April and May are closed to any taking of grunion, according to local scientists, who also urge people to "observe and conserve."

To find out about the next run, visit Cabrillo's grunion page.