In the darkness of a new moon, a dozen black-crowned night herons landed on a San Pedro beach and stood like sentinels facing the open ocean.
"That's a good sign," whispered marine biology researcher Jenn Corpuz, 26. "The herons know there is something coming."
Suddenly, the surf shimmered with flashes of silver, and a few small, slender fish wriggled on shore, as if to size up the situation. Then thousands of fish began riding in on the swells and piling up on the beach in writhing clots. "Grunion!" she said. "Turn on your flashlights, everybody!"
About 400 onlookers dashed to the shore to witness the reproductive mayhem of Leuresthes tenuis, the iconic Southern California fish that leaves its briny realm to mate on the sand.
They also were watching the launch of a scientific attempt to establish the world's first sustainable captive population of grunion -- a lofty goal for California marine aquariums. A half-dozen researchers and volunteers in white lab coats and cutoffs waded into the surf with plastic buckets, collecting as many as possible, then gently coaxing eggs and sperm into specimen vials before setting them free.
For several hours, the tiny strip of intensely urbanized beach next to one of the world's busiest ports was a landing zone for wave after wave of the 6-inch night-time spawners: vibrant, vulnerable and acutely aware they had little time to complete their urgent business.
In the center of the action was Kiersten Darrow, research curator at the Cabrillo Marine Aquarium, and the team specially trained to use both hands to squeeze out grunion eggs and milt without harming the wrigglers.
Some of the pinkish gooey results were blended in a plexiglass bucket to fertilize the eggs on the spot. Other samples were hustled to the aquarium laboratory a few hundred yards away to be flash-frozen by dipping the specimen vials in a tank of liquid nitrogen -- which is slightly warmer than the surface of Pluto -- and stored in an ultra-cold refrigerated biological archive.
Cryo-preserved samples will be revived as needed by carefully heating them up, first with dry ice, then with icy saline solution and finally with cold ocean water.
"We'll get fertilization rates of about 10%," Darrow said, "which is fine for our purposes."
