Santa Monica Beach was dark as the tide began to rise last Monday night, and all along the shore, just past the purple gleam of the Pacific Park Ferris wheel, the grunion were running.

A wave crashed up on the dark sand and, as it ebbed back into the Pacific, its retreating foam revealed a writhing silver fish — then another and another. A dozen or so fish flipped desperately back toward the dark churning water, illuminated by a flashlight beam. 

Then they were gone.

Monday, May 2, marked the middle of a four-day predicted grunion run, when the fish thrash themselves on shores up and down Southern California to spawn. Runs occur when conditions are right, but “only the grunion know for sure where they will be on a given night,” according to Pepperdine University Distinguished Professor Emeritus Karen Martin, PhD, a grunion expert.

For years, Martin and her team have sought to educate the public about the fish as well as tracking their spawning patterns and numbers. There are two grunion species: one native to the Gulf of Mexico and the other native to Southern California and Baja California. The silvery, hotdog-sized species share a unique spawning method, where females wriggle into the sand to lay eggs during high tides.

“Grunion runs occur at night, twice a month, after the highest tides associated with a full or new moon,” according to a website Martin’s team maintains: 

On Monday, that meant the run was predicted between 10:30 p.m. and 12:30 a.m. and, by about 11:15 p.m., dozens of grunion were throwing themselves up onto the sand. 

“Grunion females dig tail-first into the soft wave-swept sand to deposit their eggs, which are fertilized by milt from the males curled about them on the surface,” according to Martin’s website. “Males and females then return to the ocean, where they live a maximum of three or four years. Both sexes can spawn repeatedly over the summer and during their lives, starting at the age of one year.”

Scientists gather data on the fish each season, but thanks to the pandemic, volunteer numbers have been down. Although there are no formal training sessions offered this season, Martin said her team was always looking for more volunteers.

“This year, people can watch Melissa’s video on the website for details about how to watch and report. The video ‘Surf, Sand & Silversides’ also streaming on the website gives more info about the biology of the grunion and the start of the Grunion Greeters and Beach Ecology Coalition,” Martin wrote in an email to the Daily Press. “They don’t need to sign up in advance for locations, just be careful and safe and then report what they see (even if the fish don’t appear) on the ‘report observations’ tab. Just takes a few minutes, and the data are used by managers and by the Department of Fish & Wildlife to track the species, along with our research.”

Sample questions include timing, precise location, number estimates and other factors like light and whether spawning is seen taking place. And surveys should be completed whether or not grunion are spotted — the lack of fish is as important a data point as their presence.

Martin also cautioned that volunteers should aim to go out in groups of two or more for safety.

Currently in California it is closed season for grunion, meaning that it is illegal to catch any of the fish. Closed season, which runs from April through June this year, is “observation only”; during open season (March and July-August), those with a license can attempt to capture the wriggly fish as they wash up on shore.

In the past, open season resumed on June 1 but, citing concerns over the longterm sustainability of the grunion fishery (according to California Fish & Wildlife), June will remain closed this year.

“The proposed regulatory changes will establish a bag and possession limit of 30 grunion for recreational fishers and close the month of June to take of grunion, shortening the open season by one month, from July 1 through March 31, for recreational fishing,” according to a Fish & Game Commission document; the change was approved in February.

Grunion are set to keep on running throughout the spring and summer, but to see them is all about being in the right place at the right time. 

Upcoming runs may take place late in the night from Monday, May 16, through Thursday, May 19 and Monday, May 30 through Thursday, June 2.