SD Grunion Run - La Jolla Shores

San Diego Grunion Run

July 26, 2025

11p start! End time will depend on grunion activity, which is approximated to end shortly before 1a.

With Roslyn Rivas and Willow Eichler from San Diego Bird Alliance

California grunion, only seen along the coast of Southern California and North Baja California, have a unique behavior: they come up on the sand to breed. This happens in concert with the lunar phases, 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 again until breeding begins again. California grunion have not been reported anywhere else in the world! This makes the grunion a unique source of food for birds migrating through San Diego in the springtime. 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.

San Diego Bird Alliance is committed to offer unique nature learning opportunities and foster connections between people and the land. 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!

Loud noises and bright lights drive away grunion. We will practice "observe and conserve" - no fish will be caught for keep. A fishing license is not required to observe the run.

Ages 10+ 

Registration is limited to 12 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.

Wear something warm! You may want to bring a small flashlight. We will be on the open coast into late night. While there is no requirement to stay for the full event, the CDFW states that the second hour of the run is usually busier. Since this event is after the peak season for grunion, and because of the nature of wildlife, we cannot guarantee we will see fish in large numbers or at all. 

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