The California grunion is a small, silvery fish found along the coasts of California and Baja California. These fish are known for their extraordinary spawning behavior, often called the “grunion run.” This unique natural phenomenon involves thousands of grunion coming ashore to lay their eggs on sandy beaches. Observers are captivated by this spectacle of fish temporarily leaving the water for reproduction.
The Grunion Running Season
Grunion runs occur from late March through August, with peak activity from late March to early June. These events are closely tied to the moon and tidal cycles, happening on nights following the full and new moons during the highest tides. These high tides allow grunion to reach farther up the beach, ensuring their eggs are deposited high enough to remain undisturbed by subsequent lower tides. The California Department of Fish and Wildlife (CDFW) publishes an annual schedule of expected grunion runs, which helps predict these occurrences a few nights after the peak of the new or full moon.
Spawning Rituals and Purpose
During a grunion run, the female grunion wriggles onto the sand, using her tail to dig a nest where she deposits her eggs. While partially buried, one or more males wrap around her to release milt, fertilizing the eggs. This process is quick, often lasting about 30 seconds. This beach spawning behavior is a survival strategy, protecting the eggs from marine predators. The eggs remain buried in the moist sand, developing over approximately 10 days, then hatch with the next series of high tides, which wash them out to sea.
Prime Viewing Locations
Grunion runs are observed along many sandy beaches throughout Southern California, from San Diego through Orange County, Los Angeles, and Ventura. They also occur further north along the California coast, though less frequently. To increase viewing chances, seek less crowded beaches. Darker beaches away from artificial lights are best, as grunion are sensitive to light and noise. The CDFW does not recommend specific beach names due to changing safety conditions and local curfews, but general location characteristics are important.
Guidelines for Observation
Those observing a grunion run must be aware of regulations. The California Department of Fish and Wildlife mandates a valid California fishing license for anyone 16 or older intending to catch grunion. Grunion can only be caught by hand; nets, traps, or digging holes are prohibited. A closed season for taking grunion runs from April 1 through June 30 to protect them during peak spawning. During this period, observation is allowed, but grunion may not be touched.
Observe quietly and from a respectful distance to avoid disturbing the fish. Avoid using flashlights directly on them, as this can deter them; a red-filtered light can be used minimally. Allowing grunion to complete their natural spawning undisturbed is important for future runs. Adhering to these guidelines helps conserve the grunion population while enjoying this natural wonder.