It’s time for Southern California beaches to turn silver as grunion season launches

Grunion season has arrived — an it’s a great excuse to go to the beach at midnight.

The annual Southern California celebration heralds the tiny fish that mate on the sand on beaches stretching from San Diego to Santa Barbara.

Orange and Los Angeles counties — and beyond — see lively grunion season activity from the tiny fish that seem to prefer sloping beaches where high tide pushes waves beyond the normal water line, protecting eggs.

Protected beaches, such as those behind the breakwater in San Pedro Bay, are especially popular with the fish. So San Pedro’s Cabrillo Beach (the inner harbor), for example, is known for hosting annual grunion runs that combine fun activities and education. That seasonal celebration kicks off at 9 p.m. Friday, April 7, and will continue through June 19.

This year’s schedule includes a special night on April 21, with World of Sound Productions bringing 500 headphones so guests can have a silent disco dance party at two locations, the Cabriillo Marine Aquarium and the beach.

“We are stoked to collaborate with Cabrillo Marine Aquarium,” said Adam Malovani, founder of World of Sound Productions, which also stages events in Hermosa Beach and Santa Monica. “This is an epic location.”

But the grunion will remain the star of the show.

During grunion season, the silvery, smelt-like fish sweep onto shore to mate, with crowds of people gathering to watch what has been called one of the most unusual phenomenon in the natural world.

The female grunion are the first to surf to shore, aiming for the highest point on the beach, pushing their tails into the sand.

Males follow, wrapping their bodies around the females for a 30-second mating ritual.

Then it’s right back out to sea for them.

The females take a bit longer to dig out of the sand, but they eventually follow.

The eggs left behind — there can be up to 3,000 of them in a pile — then stay buried until the next high tide rolls in a couple of weeks later, stirring the sand and helping the eggs hatch. The infants are then carried back into the water by the tides.

Then, it happens all over again.

Catching grunion — with a fishing license — is legal in March, June, July and August, but not in April and May, when you can only watch in order to allow the species to reproduce propagation.

Grunion can be cooked and the runs, during catching season, are a good way to get fresh seafood.

The spectacle can be seen on numerous beaches, including:

• Corona Del Mar State Beach.
• Newport Municipal Beach.
• Bolsa Chica State Beach.
• Seal Beach.
• Belmont Shore Beach in Long Beach.
• Long Beach City Beach.
• Hermosa City Beach.
• Manhattan County Beach.
• Venice City Beach.
• Santa Monica State Beach.
• Topanga Beach.
• Malibu Surfrider Beach.

The best runs, according to the California Beaches website, occur after new or full moons. Grunion, one of only a few species that come onshore to lay their eggs on sandy beaches, are most likely to surface after the highest tides and the largest numbers of fish can generally be seen about an hour after a run has begun.

Avoid using flashlights, though, as the illumination can scare the fish away. Regulations require that the fish, during catching seasons, can only be caught by hand, with no tools.

But mainly, folks go to grunion runs because, well, they’re fun.

“It’s a great excuse to stay up late and go to the beach,” Crislyn McKerron, director of the Cabrillo aquarium, said in a recent news release.

Since 1950, the Cabrillo Marine Aquarium has been curating grunion runs for the pubic and it remains one of the best places to observe the phenomenon.

At times, the beach can look like it’s covered in a blanket of silver as the fish arrive.

The aquarium, 3720 Stephen M. White Drive, combines its events with a movie beforehand that teaches about the grunion, as well as opportunities to hatch grunion eggs and explore the rest of the aquarium before heading to the beach for the predicted run, which begings anywhere from 10:15 to 11 p.m.

“Meet the Grunion” program nights are:

• 9 p.m. Friday, April 7.
• 8 p.m. Friday, April 21.
• 8 p.m. Sunday, May 21.
• 8 p.m. Monday, June 5.
• 8 p.m. Monday, June 19.

Admission is $7 for adults, and $3 for seniors, students and children. Members of the Friends of the Aquarium are admitted for free.

Tickets can be purchased at cabrillomarineaquarium.org.

For the silent disco event on April 21, visitors must rent headphones for $20 per adult and $10 for children 12 and under at sunsetvibesevents.com. There will be other activities coordinated with that event as well, including a station geared for families.

Beach parking is $3 and the lot closes at midnight.