JAUNTS : Grunion Set to Make Run for the Beach : The small, silver fish swarm the shores in a mating ritual that provides a fascinating glimpse of nature.

If you slip down to the beach about bedtime this weekend and find a deserted stretch of sand, you might catch a bundle of fish--with your bare hands.

Yes, the grunion are coming. Those elusive little fish that glide in with the high tide for a bizarre mating dance in the sand have begun their spawning season.

If you’re lucky, you might witness this strange sight Saturday, Sunday, Monday and Tuesday nights during the two-hour spans when the fish come ashore to deposit their eggs in the sand.

During that time, grunion hunters with gunnysacks and pails can scurry across the sand and try to grab the grunion before the fish catch the next wave back into the ocean. Or, they can simply watch the spectacle.

Either way, don’t get your hopes up. It’s not a sure bet that the silvery fish will pick your stretch of beach to do their thing. Not only that, the grunion are crafty and extra-sensitive about the presence of humans.

“The grunion send out a scout to check the beach,” said Kathy Dolinar, a state parks ranger. If it’s picked up, the others will stay away.

It’s best to wait until the fish appear in droves, flipping and flopping on the beach, Dolinar said. Sit on the beach quietly, avoid stomping around on the sand, and try not to use a flashlight. The best nights are Sunday and Monday.

Dolinar has seen hundreds of grunion wash up onto the sand at the end of Seaward Avenue in Ventura. She has seen them near the Ventura Pier and at nearby San Buenaventura State Beach and at McGrath State Beach.

“It’s neat to watch,” she said.

The grunion run is a Southern California phenomenon, occurring from Point Conception to Baja California. The runs begin in March and continue through August. The state Department of Fish and Game plots out to the minute exactly when they will occur. They are always over a four-night stretch from two to six nights after a full moon and a new moon.

Plucking the grunion out of the sand is permitted, although a fishing license is required for anyone 16 and older. The fish, five to six inches long, have to be taken by hand. There is no limit, but wasting fish is against the law. (If you cook and eat them, they’re especially bony.)

To keep grunion abundant, the state doesn’t allow them to be snatched during April and May, prime mating season. But during March, June, July and August runs, they are fair game. Simply watching the fish dancing on the sand during the off season is satisfying enough, fish experts say.

“They’re wiggling around on the sand, looking like they’ve just been left stranded--hundreds of them, all silvery in the moonlight,” said Susanne Lawrenz-Miller, who heads San Pedro’s Cabrillo Marine Aquarium, where grunion are studied.

Just how the little fish have become so finely tuned to the tidal rhythms of the ocean is something of a mystery. But this much is known: Beginning a little after the highest of high tides, the grunion ride the waves in, swimming as far up the beach as possible.

“The female fish wriggles into the sand, tail first,” Lawrenz-Miller said.

There, half buried, she deposits her eggs. Then male grunions curve themselves around the female and release secretions that fertilize the eggs. With a jerking motion, the female frees herself and catches the next wave out to sea. It usually takes less than a minute.

The eggs hatch in about 10 days, when the next tide high enough to reach them arrives and sweeps them back to sea.

Details

* WHAT: Grunion runs.

* WHEN: Saturday, 10:05 p.m. to 12:05 a.m.; Sunday, 10:45 p.m. to 12:45 a.m.; Monday, 11:30 p.m. to 1:30 a.m., and Tuesday, 12:25 to 2:25 a.m. Grunion runs are predicted from March through August. Next run April 1 to 4.

* WHERE: Anywhere along the Southern California coast.

* INFORMATION: (310) 590-5132.

* FYI: Anyone 16 and older needs a state fishing license to take grunion.