REDONDO BEACH, Calif. (AP) -- After a night of gusty winds rocking their vessels, boaters in a Southern California marina awakened to find a carpet of silvery fish. About one million lifeless sardines packed into the harbor, stacking 12- to 18-inches deep in some spots.
The sardines apparently depleted the water of oxygen and suffocated after getting lost in the marina, officials said. Despite a daylong effort Tuesday to scoop up fish in nets and buckets, the cleanup can take up to a week and the smell was bound to get worse.
"All indications are it's a naturally occurring event," said Andrew Hughan, a California Fish and Game spokesman.
The die-off was unusual but not unprecedented.
"In the world of fishing, this is an afternoon's catch," he noted.
The scale was impressive to locals at King Harbor Marina, which shelters about 1,400 boats on the Los Angeles County coast.
"The fishermen say they've never seen anything this bad that wasn't red tide," Hughan said, referring to the natural blooms of toxic algae that can kill fish.
Hughan said water samples showed no oils or chemicals that could have contributed to the deaths. He said some of the fish were being shipped to a Fish and Game laboratory for study but the cause was likely to be uncomplicated.
The fish appeared to have come into the marina during the night and probably got lost, he said. The 30-foot-deep marina simply couldn't provide enough oxygen for such a massive influx of fish.
Two tests of some of the water on Tuesday showed oxygen levels near zero.
Yet other theories abound.
Hughan noted that some fishermen reported waves coming over the harbor breakwaters during the night. That washes bird excrement off the rocks and into the marina, and can cause the water to be depleted of oxygen.
Staci Gabrielli, marine coordinator for King Harbor, said the fish appeared to have moved into the harbor to escape a red tide, then possibly became trapped due to high winds overnight.
Ed Parnell, a marine ecologist at Scripps Institution of Oceanography, called Gabrielli's theory plausible, although generally he would expect the wind would have mixed oxygen into the water.
Parnell said these types of fish kills are more typically seen in the Gulf of Mexico or the Salton Sea, the enormous desert lake in southeastern California where millions of fish die with some regularity.
Brent Scheiwe, an official of Sea Lab, a Los Angeles Conservation Corps research program, said the fish may have gotten trapped in the marina while sheltering from rough seas overnight.
"They like to follow each other, so it only takes a few" to create a mass migration, he said.
"Over time, they will find their way out, but if it's rough out there they probably stayed in shelter," he added.
Redondo Beach police Sgt. Phil Keenan said he believed a predator fish chased the sardines into the marina where their sheer numbers caused them to suffocate.
Raphael Kudela, a professor of ocean sciences at University of California, Santa Cruz, said sardines are not the brightest fish.
"They are that dumb actually," he said. "They get into shallow water and then can't figure out how to get back out, and you've got such a concentration in one small area they literally pull the oxygen down until they suffocate."
Fire department, harbor patrol and other city workers were expected to continue dredging up the fish and haul truckloads of them to a landfill, where they will be turned into fertilizer. City officials estimated the cleanup would cost $100,000.
On the water, nature was tackling the problem in other ways. Seals and pelicans flocked to the marina to feast on sardines, and large groups of other fish were seen nibbling at the floating mats of their dead brethren.
Carl Johnson, 59, and his wife, Marie, 57, came from nearby Torrance to see the fish calamity.
"We've had that stuff of the hundreds of birds dying in the Midwest, and now this. ... You do think about life and death," he said.
"These fish were swimming freely yesterday," he said philosophically.
Marie Johnson added: "It's really sad."
Associated Press writer Noaki Schwartz in Los Angeles contributed to this report.