Grunion Run

Sunday, May 3, 10:00 PM to midnight

Greet the Grunion! with San Diego Bird Alliance and Beach Ecology Coalition

For only a few months out of the year, fish known as California Grunion come up out of the ocean and onto sandy beaches to spawn, in an event called a grunion run. Observing and collecting data on grunion runs is the only way for scientists to track grunion populations - and you can help! Prepare to Greet the Grunion by watching this instructional video from Beach Ecology Coalition. 

Loud noises and bright lights drive away grunion. Fish will be observed only - not taken or caught. From CADFW, “REMINDER: Grunion season is closed for April, May, and June. During the closed season, contact with grunion is prohibited to allow for uninterrupted spawning. However, discreet observation of grunion runs is permitted during the closed season.”

Ages 10+ 

Registration is limited to 30 participants, as any large disturbance on the sand can drive away the grunion before a run even begins. Specific meeting details will be provided in an email prior to the trip.

We will be on the open coast late - up to two hours from the event start time. Dress appropriately - it may get cold and windy at night. Wear footwear you don’t mind getting wet, like sandals or water shoes (barefoot not advised). Restrooms are open 24 hours. Because of the nature of wildlife, we cannot guarantee we will see fish in large numbers or at all. 

Grunion & Birds

California Grunion have a unique behavior: they come up on the sand to breed. This happens in concert with the highest tides associated with a full or new moon, and can only be seen at night. Interestingly, their breeding behavior is the only reason scientists know these fish exist! Beyond the breeding season, the grunion return to open sea and are not seen until breeding begins again. Runs have been documented along the Pacific Coast from Baja up to San Francisco, and aren’t found anywhere else in the world! 

This makes the grunion a unique source of food for birds living in and migrating through San Diego in the springtime - and for people, too! These fish also connect us, through time, to Kumeyaay, Luiseño, Tongva, and other native peoples and cultures across this coastal region where the grunion spawn. People have observed, caught, and eaten these fish for centuries. Read more about the phenomenon in this Patch article.

Birds are the grunion's main predators, and the birds' behaviors are one of the best indicators for locating the grunion to begin with. Even birds who are not nocturnal will change their behavior and wait to hunt the grunion at night (here's a cool paper about that), including gulls, egrets, and herons!

For your entertainment, learn about the grunion along with some of the other unique and amazing wildlife in San Diego:

PBS Documentary Featuring the Grunion

A PBS Nature special, "San Diego: America’s Wildest City", premiered on National PBS on Wednesday 11/6/24 at 8 pm as part of their "Nature" series. A film by @daysedge @pbsnature @terramater. If you're in San Diego, the film is being shown at the San Diego Natural History Museum on the IMAX big screen daily November 22, 2024 through December 31, 2025. Watch the trailer. The documentary is available on PBS, You Tube and Apple TV as well.