Grunion runs possible between Thursday and Sunday

Grunions, a type of marine fish found only off the coast of Baja and Southern California, may be spawning Thursday night through Sunday night on nearby beaches, according to a schedule of breeding periods produced by the California Department of Fish and Wildlife.

The fish have a highly unusual reproductive process, in that they come onto land to spawn. Females come first, digging holes and laying eggs, followed by males which fertilize the eggs. The reproductive events are known as grunion runs, which occur late at night, usually over two-hour intervals during a full moon when tides are most extreme.

“Over the next four nights there’s a good possibility for grunion runs,” Dana Murray, a marine scientist at Heal the Bay, said Thursday. “It looks like a silvery fish wave on the sand, they’re all flip-flopping, the moonlight will catch the scales, it’s really cool.”

Malibu beaches are ideal locations to witness this unique phenomenon, Murray said, especially Surfrider Beach. The most likely time to see a grunion run is listed in this table, with the second hour likelier to be better. The best potential runs are expected to occur on Saturday and Sunday: 

In April and May it is illegal to catch grunions in California due to their spawning season, so leave any buckets at home. People are also urged not to approach the grunions. 

“You can actually scare off a grunion run, because we look like predators. Be a little quiet, don’t shine a light, but it can be really exciting. Sometimes there can be thousands on the beach,” Murray said. 

The fertilized orange grunion eggs that are left behind remain in the sand for two weeks, incubating completely out of water until another high tide comes in and they hatch, washing into the ocean. 

The eggs are vulnerable during this period to humans stepping on them or dogs eating them, so people walking along the beach should take care to be careful where they walk and to watch their dogs. 

“Their population is believed to have gotten low, so this closed season it’s important to protect them during spawning for the future population,” Murray said. 

Observers of grunion runs are urged to report the time and location of the run for scientific purposes at this web address: http://www.surveymonkey.com/s/Grunion2013.

For more information on grunions and what they are, go here. 

Associate Editor Knowles Adkisson may be reached at 310-456-5507 ext. 109 or knowles@malibutimes.com.