The grunion are running this weekend! Here's where, when and how to see them

A cherished tradition in Southern California will resume Saturday night, when spectators will gather on sandy beaches to see the California grunion run.

What’s a grunion?

The grunion (rhymes with onion) is an inches-long ocean-dwelling fish with a mating ritual that has long fascinated human bystanders. That’s because the fish wriggle their way out of the water and up onto the sand in order to do their thing.

Females use their tails to dig nests in the sand into which they lay thousands of eggs. Males entwine themselves around the half-buried females, releasing “milt” which then travels down along the females’ bodies to fertilize the eggs.

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For decades (centuries according to Pepperdine University), it has been tradition for people to gather to see the fish blanket area beaches with their wriggling bodies.

Karen Lynn Martin, a biology professor at Pepperdine University and a leading expert on the grunion, said that the spectacle is breathtaking.

“What you’ll see is a wave crash up on the beach, and when it goes back, it’ll leave behind all this silvery dancing on the shoreline,” Martin said. “Quite beautiful.”

Video of grunion spawning on June 16, 2014, near Malibu, CA 

If you’d like to see it yourself,  we’ve gathered some information for you.

When the grunion run

Grunions spawn from March through August. They are protected from fishing during April and May, when spawning is at its peak.

For four nights, following full and new moons, spawning will occur for a couple hours after high tides.

The California Department of Fish and Wildlife has listed the likely dates and times for grunion spawning. Visit the page for further details.

Screenshot taken from California Department of Fish and Wildlife's grunion page

Where to see them

The grunion’s range from Central California down through Baja California. Martin said that any sandy beach is fair game, but some luck is required, because it’s impossible to know which beaches the fish will visit.

She typically doesn’t name any beaches for fear that too many people will gather and make the spot less appealing to the grunion.

Cabrillo Marine Aquarium has public programming ($5 for adults; $1 for children, seniors and students) that takes visitors down to Cabrillo Beach. Its next program is scheduled for Sunday, April 5 at 8 pm.

Birch Aquarium will also run its next program ($16 for public; $14 for members) on Sunday, beginning at 9:30 pm.

Do’s and Don’ts

Martin said that grunions can be sensitive to noise and that people who are watching should avoid being a distraction.

“Think about what you’d do if you were trying to watch a deer or some birds. Just kind of be quiet and give them some space,” Martin said.

• Bring warm clothes and a flashlight
• Stand back away from the waves to give the fish plenty of space
• Don’t wave flashlights at the fish
• Don’t make a lot of noise
• Don’t try to catch them, because that’s currently illegal
• “Do enjoy the spectacle,” Martin said. “It’s a natural phenomenon that you can’t see anywhere else.”

Last note

The numbers of grunions seen appears to have taken a dip during the past four years. The exact reasons for this aren’t known, but Martin said that unusually warm water in recent years may be driving down the availability of food for the fish.

Regardless, she wrote in an email that nothing should discourage people from making the attempt to see them.

“One more thought, it is never a waste of time to stand on the shore under a full moon. Even if the fish don't show.”