Southern California: Grunion Run – Spawning on the Sand

If your date invites you on a moonlight stroll along the beach, but asks you to bring a flashlight, bucket and sense of adventure – it can mean only one thing. It’s grunion season. A uniquely strange phenomenon on Southern California beaches, grunion runs occur from March until August from Point Conception to Baja California. It’s quite a sight to see.

For the unfamiliar, the grunion is a toothless, smelt-like fish about 5 to 6 inches long. For four consecutive nights, beginning on the nights of the full and new moons, thousands of the silvery fish wiggle their way to the shore at high tide for a most interesting mating ritual. The females dig themselves into the sand, twisting and turning to create a nest, and deposit their eggs. The males wrap around the females and release milt, which flows down the female’s body to fertilize the eggs. After spawning, the grunion ride the next big wave back to sea while the breaker covers the roe with sand.  The eggs incubate in the sand during the lower tides and hatch about 10 days later during the next high tide series. Females can lay up to 3,600 eggs during one spawn and can spawn up to six times in one season. The life span of a grunion is two to three years.

Grunion runs are fun and fascinating to observe, but you may also catch these feisty creatures. A fishing license is required for anyone 16 years and older. The fish may only be caught with bare hands – no other tools may be used and no holes may be dug in the beach to entrap the fish. There is no limit to the amount that may be caught. Grunion season is closed April and May.

Visit the California Department of Fish & Game to see a list of expected dates and times of 2011 Grunion Runs.