Earth Systems Science, Inc.

ESSI CALIFORNIA NATURE TRIP: THE GRUNION RUN

Jun 12, 2004

The California Grunion (Leuresthes tenuis), was the subject of a recent ESSI Y.E.S. California Nature Trip. [Note: Y.E.S. stands for Youth, Environment, and Sustainability. It is one of the underlying concepts of Earth Systems Science, Inc. (ESSI), a California non-profit providing environmental education for urban families and sustainable neighborhoods.)
The California Nature Trips focus on ?“unique?” natural wonders of California. The California Grunion is reputed to be the only fish that lays its eggs on land. This is a survival strategy relying on the tidal cycle to place Grunion eggs in sand above the average high tide mark for about 10 days. During that time, the eggs are incubated in safety, away from natural predators (who tend to stay in the water and wet sand).
?“This is so interesting,?” commented one student. ?“I?’ve lived in California all my life and never saw this before!?” ?“When I first heard about this, I couldn?’t believe it was possible. Now that I am here and see it, I can still hardly believe it!?” remarked another. ?“I?’ve never seen so many fish in one place all at the same time,?” was another comment.
The Grunion ?“Run?” (more properly called a spawn) occurs an hour or so just after the peak ?“spring?” tide, usually late at night (10 pm to after mid-night). This tide is higher than the average high tide. The late hour of this beach event combined with the romantic inclinations of youth led to many teens telling their parents they were going to see a ?“Grunion run?” --- but not seeing any Grunion. This led to elevating this natural wonder to an almost mythical level that many people don?’t believe Grunion really exist. They?’ve heard of so many people going to the beach to look for the Grunion---but return from the night?’s outing and report they didn?’t see any at all.
ESSI recently led a group of students accompanied by Thai DTV (Digital Television) to the ?“Meet the Grunion?” program at the Marine Cabrillo Museum in San Pedro, CA. ?“We like to introduce people to the California Grunion here because the Museum?’s program is very well organized and informative,?” said Gregory Lee, CEO of ESSI. The program includes an educational talk, a National Geographic film of a Grunion Run, a hands-on Grunion egg hatching activity (they collect the ?“fry?”---newly hatched baby Grunion---and release them in the ocean), and a chance to try to see the spawn at the beach near the Museum. As with many natural phenomena, direct observation is not guaranteed. After all, the Grunion are not paid performers.
The Grunion do not migrate. They live is the waters just off the beach. And they are wary of being eaten. So during the spawn, scouts approach the beach first. If all is quiet, more and more Grunion appear out of the night waters to beach themselves on the sand. Like body surfers, they ride a wave in to shore. The white foaming water is bubbling and swirling as it washes up the beach. The silvery Grunion appear as if by magic to strand themselves on the sand. The females use their tail to burrow down in the wet sand and begin to lay eggs. Males arrive on a successive wave, curl themselves next to the burrowed female and deposit their milt to fertilize the buried eggs. Another arriving wave washes over the scene, and the fish return to the sea.
At its peak, the beach can be silver with thousands of fish! And it can all be over in a matter of 15 minutes! To the uninformed and inattentive, the whole event could pass without notice. A beach once covered with thousands of wriggling Grunion is now quiet, smoothed over, and peaceful----and the ?“boring?” repetitive swish, swash of the waves goes on endlessly ?… until the next ?“spring?” tide occurs about 2 weeks later.
Watch the ESSI website Calendar for future California Nature Trips. If you?’d like to learn more about the California Grunion and support ESSI Y.E.S. activities, send for the ESSI Grunion Run trip booklet. Enclose a long, self-addressed stamped envelope (with 74 cents postage) and $3 to ESSI-Grunion, PO Box 8042, Van Nuys, CA 91409-8042. Please do not send cash; make checks or money orders payable to Earth Systems Science, Inc.

[ESSI Editor's Note: This event was also featured on the front page of the 28 May 2004 issue of Thaitown USA newspaper and in vol. 33 of Mai-Thai Magazine (pgs. 36-40, 88).