See How They Run

Along a narrow strip of the Pacific coast, shortly after the evening's highest tide, the shoreline begins to sparkle with silvery light every spring, heralding the start of one of marine life's most spectacular phenomena.

Each year throngs of California grunion, small, sardine-size fish found only along the southern coast of California and parts of northern Baja California, swim, or “run,” to shore as part of their unusual spawning ritual. The annual occurrence often lasts through summer and draws curious audiences eager to catch sight of the magnificent fish species that has intrigued both scientists and spectators for centuries.

With each new or full moon, a small group of male grunion catches a wave onshore and, swell-after-swell, is joined by as many as thousands of others, males and females, that may eventually blanket the beach with their flopping, luminescent bodies.

Grunion photos courtesy of Dan Harding

The mating “dance” lasts anywhere from a few minutes to an hour or more, when females burrow themselves in the sand to deposit their ova, sometimes up to 3,000 at a time. Drawn to their fascinating motion, the males wrap themselves around their mates to fertilize the eggs and quickly return to the surf. While females make the journey to shore only once, males return several times to repeat the process. The eggs, which are buried inches beneath the sand, incubate for 10 to 12 days until the next high tide washes them into the ocean to hatch.

Seaver professor Karen Martin, the region’s best known expert on grunion, has been studying the small and slender fish for about 20 years and first became interested in the species while researching fish that come out of water for her doctoral dissertation.

“I hadn’t planned on looking at grunion when I first started my research as a student,” she says. “I found it difficult, because the timing was all wrong and I couldn’t ever find them, so it took me a while to start looking at them again.”

Grunion are famously elusive and are one of the few species of fishes that come out of water to spawn. Because of their inability to be found when not on shore, they are also difficult to study.

It wasn’t until Martin began teaching at Pepperdine that she revived her investigation of the beach-spawning fish. Her research now focuses on their early development, the grunion’s most vulnerable period of life.

Grunion eggs, explains Martin, develop on land and don’t hatch until they return to the ocean. “Not only is that an interesting situation in itself, but also, if they are not triggered to hatch, they can stay at the same stage of development for a long period of time: up to two to three weeks after the time that they’re ready to hatch. They stop developing, but stay alert and aware of their surroundings.”

The life span of the grunion is two or three years. Humans pose the greatest threat to their short- and long-term survival.

As the executive director of Grunion Greeters, Martin and colleagues first organized a team of volunteer citizen scientists in 2002 to study the human impact on the fish’s habitat and collect data during spawning runs that is later used for research and management.

The group formed after members of the public became concerned about the way that the beaches were being maintained in San Diego. “A local citizen noticed the way that they were raking beaches and thought that they were probably going to cause harm to the eggs that were buried in the sand after the grunion had run,” she recalls.

Due to their very small habitat range, and their role near the bottom of the food chain, the grunion population faces a very real threat of depletion. “There is a lot of activity on beaches in the summertime,” she explains. “Grunion eggs are susceptible to the impact of driving, construction, sea walls, and the changing natural supply of sand and natural wave action on the beaches.”

Martin’s work with Grunion Greeters was her first experience involving the public in her research, and the first event was an unexpected success. “We were looking for volunteers to help us watch for the grunion, but I wasn’t sure that anybody would show up to hear about it and help us with that project,” she says. “I was very surprised when several hundred people showed up and were very excited about helping us.”

With the aid of residents, scientists, public agencies including the California Department of Fish and Wildlife, California State Parks, the National Marine Fisheries Service, NOAA, and local governments, and volunteers, the results of the initial study of beach grooming practices prompted significant change in official procedures in San Diego and other cities throughout California.

The Grunion Greeters also make recommendations for the vehicles that patrol the beaches and the ways the beaches are maintained that will protect the areas where grunion nests are located.

A closed season allows the grunion to be able to reproduce without any interference from people onshore. Hunting is prohibited during April and May. To give grunion more of a chance to survive during the open season, restrictions on how they can be hunted were put in place in 1927.

Currently at Pepperdine Martin, along with colleagues from UC Santa Barbara, is establishing a citizen science program called All Ashore, an initiative that will engage students and local volunteers in monitoring sandy beaches and examining their ecology to educate and help the community understand the kinds of organisms that they might find there. It will provide a comprehensive look at all the animals and plants, not only grunion, that inhabit the sandy beaches in Southern California and partner with organizations up and down the coast, including aquariums, environmental organizations like the Surfrider Foundation, Heal the Bay, and Santa Barbara Channel Keepers, as well as other groups. Martin and her colleagues are also developing a web-based questionnaire to survey the beaches in preparation for training sessions and workshops for citizen volunteers to collect data.

“People tend to be less aware of the ecology of beaches than they are of other marine environments,” she explains. “They are very aware of the ecology of tide pools, or wetlands, or kelp forests, but they don’t think about sandy beaches as an ecosystem.”

Seaver graduate Vincent Quach (‘14) is helping Martin with this program and junior Emily Pierce, who participated in Pepperdine’s Summer Undergraduate Research in Biology program, is taking part in researching the hatching process of the grunion to understand how they are able to hatch so quickly.

Pierce’s first experience with grunion took place during a run last summer and reinforced her research pursuits.

“It is incredible to see the natural process happening,” she says. “People will come up and ask us what we’re doing while we’re out on the beach finding grunion eggs.”

Martin’s recently released third book, Beach-Spawning Fishes: Reproduction in an Endangered Ecosystem, takes a closer look at the similarities and differences between grunion and many other fish species that have similar behaviors on beaches all around the world. Her research throughout has been supported by grants and contracts from the National Science Foundation, the National Marine Fisheries Service, SeaGrant, NOAA, the National Parks Service, and the National Geographic Society, among others. In 2010,

along with Seaver journalism professor Michael Murrie, Martin produced Surf, Sand, and Silversides: The California Grunion, an award-winning, short educational film about California grunion that was screened at film festivals and is available for educators.

“Like most areas of science, every question you ask about grunion leads to another question,” she says, “so you just keep going.”

“When I first started looking at grunion, I was working with students and a very small group of collaborators, but now I realize that we have to involve the public and the people who work at beaches and, really, the whole community.”

Learn more about grunion: grunion.pepperdine.edu

Watch a video of a grunion run recorded June 16 near Malibu, California: