Grunion Run Season in San Diego: When and Where to Watch (or Catch)

A few nights a month, thousands of small silver fish throw themselves onto Southern California beaches to spawn — by hand, in the open air, visible by flashlight. It's one of the strangest sights on the California coast, and it runs on a schedule you can actually predict.

What a grunion run actually is

California grunion are small, slender fish found only along the coast of Southern California and northern Baja California, from roughly Point Conception down to Point Abreojos. A few nights each month during spawning season, grunion ride the waves onto sandy beaches, and the females dig tail-first into the wet sand to lay eggs while males curl around them to fertilize them — the entire spawning act happening out of the water, in the open, for several minutes at a time. The eggs incubate in the sand through the following lower tides and hatch roughly ten days later, timed to the next round of high tides that re-wet the sand and let the hatchlings wash out to sea.

When it happens

Grunion runs occur on the nights of the full and new moon, for four consecutive nights, after the evening high tide — the runs are timed to the tide cycle, not the calendar, which is why the exact minute shifts slightly night to night and place to place. Spawning season runs March through August, occasionally stretching into February or September, with the heaviest runs from late March through early June. Within any given four-night window, the second and third nights tend to produce the best runs.

Run timing also varies slightly by location along the coast — San Diego's runs typically start a few minutes earlier than the schedules published for beaches further north like Cabrillo Beach in LA County. CDFW and several local organizations publish the predicted date-and-time windows each season; checking the current year's published schedule for the specific date and tide window is the only reliable way to plan a trip, since exact minute-level timing isn't something to estimate from general seasonal patterns.

Where to watch in San Diego

Grunion spawn on open, gently sloping sandy beaches up and down the San Diego coast — CDFW doesn't single out one official beach, and conditions shift from year to year, so local lifeguards are often the best same-week source on where a run was recently seen. Wide, flat sandy beaches with minimal rock or reef tend to be the most reliable bet.

The closed season — and the rules if you want to catch some

• License required. Anyone 16 or older needs a valid California sport fishing license (with the ocean enhancement stamp) to take grunion — watching doesn't require one, but any handling does, even if you release them.
• Hand-only. Grunion may only be caught by hand. No nets, no bags, no digging holes in the sand to trap them.
• Bag limit. 30 fish per person, per day.

As with any CDFW regulation, season dates and limits are set and occasionally adjusted year to year — check the current year's published grunion schedule and regulations before you go, rather than relying on a general date range.