According to the California Department of Fish & Game, August 24-26, 2010, are the expected dates of the grunion runs for the 2010 calendar year. Grunion normally range from Point Conception, California, to Point Abreojos, Baja California. Grunion habitat consists of nearshore waters from the crashing surf to about a depth of 60 feet.
What makes the grunion run so special is the fact that these fish and their spawning behavior are incredibly unique and famous. Unlike other fish, grunion come out of the water at night to spawn on beaches during spring and summer. Spawning occurs after high tides for four nights in a row, beginning on the nights of the full and the new moons. The spawning actually lasts for a number of hours each night. The grunion will swim as far up the beach as possible, and the female digs in the sand using her tail and creates a nest. Once she has dug far enough to become half-buried, she will deposit her eggs. The male grunion then also swim up the beach to the female, and will wrap around her and release milt. The milt will eventually reach the eggs and fertilize them. The male grunion will then head back into the crashing surf, while the female un-digs herself and heads back into the ocean. The eggs will hatch about 10 days later.
Grunion can be harvested, but only during open season, and only if you have a fishing license (not needed for children under 16). Harvesting can only be done using hands and without digging holes or other activities to trap them on the beach.
On average, a southern California grunion spotted during the run will be about 5-6 inches in length.
Photo from Wikipedia