Run, Grunion, Run: This South Bay Beach Will Soon Be Filled With A Unique Fish

SAN PEDRO, CA — Some people don’t think miracles happen, but in the case of the grunion — a small fish exclusive to Southern California beaches — the way it reproduces is nothing short of it.

The California grunion may be an ordinary-looking silver fish, only six to eight inches long. But what makes them unique is that they're one of the only fish that come out of the water to dig in the sand and lay their eggs.

But, no, they don't walk or flop out of the water, Jim DePompei, Programs Director of the Cabrillo Beach Aquarium, told Patch.

"They're in tune with the moon cycles," DePompei explained. "Around new moons and full moons, tides are extremely high or extremely low. They will come up right after a new moon or a full moon, so they'll be able to ride the swash zone. They ride that surf as far up the beach as they can."

The female grunion will dig into the sand and lay about 3,000 eggs, DePompei said, adding that they can lay up to 18,000 eggs in a season. A male grunion will then wait for a ride up the beach and try to find eggs to fertilize.

The grunion, which can survive outside of the water for about 20 minutes, will then wait for another high tide to take them back into the ocean, DePompei said.

The fertilized eggs take about 10 days to incubate, the length of the next month's cycle. Those baby grunion then ride their wave back into the sea.

This sight is common during mating season, which runs from spring to summer. The grunion may be seen up and down Southern California beaches, but DePompei said the silver fish tends to appear consistently at Cabrillo Beach.

"It's crazy to think about, but it's amazing to see thousands and thousands and thousands of these fish flopping on the beach," DePompei said. "They're up and down and then there are thousands more waiting to go up on the beach."

DePompei said the first grunion run was started by John Olguin in 1950. The idea was to connect the community to nature, according to DePompei.

Since then, the Cabrillo Beach Aquarium has conducted its "Meet The Grunion" program to teach people about the grunion, have them see it in person and allow them to see an egg hatch.

The event involves watching an educational movie, placing the eggs in a sand-filled jar and emulating the ocean until the babies hatch, DePompei said. Then, people will be taken to the beach to see for themselves how the grunion run.

"The first time I did it, my mind was blown," DePompei said. "Every time since then, that I've hatched a grunion, it's the exact same feeling. I never get tired of it. I think it's one of the coolest things around."

Although the grunion is exclusive to SoCal, there is a subspecies called the Gulf grunion in Baja California that behaves similarly. Scientists believe the two groups of grunion separated when Baja California struck the North American plate, DePompei said.

While the Gulf grunion still come out of the water to lay eggs, they doen't travel as far as the California grunion, DePompei said.

The Cabrillo Beach Aquarium will have three more "Meet The Grunion" events over the next month and a half. Here is the schedule:

• May 28 at 9 p.m.
• June 13 at 7 p.m.
• June 27 at 8 p.m.

Tickets for the event can be purchased in person ($7 for adults and $3 for children).

"If you're in Southern California, you should go see the grunion run," DePompei said. "It's something people have been doing for thousands of years. Not only is it a tradition in Southern California, but it's one of the many things in Southern California that makes us such a unique location."