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California and the West | Signs of the Tides

Sea Scoters, Many Too Fat to Fly, Have El Nino to Thank for Crab Bounty

March 15, 1998|LISA FERNANDEZ | SPECIAL TO THE TIMES

ANACAPA ISLAND — Too fat to fly.

In yet another manifestation of El Nino, scores of pudgy brown ducks are gorging themselves on swarms of tiny red crabs swept north by this season's unusual ocean currents.

The fowl flutter their wings, they scoot hurriedly along the water's surface, they appear to be taking off and . . .

Nothing.

The birds, known as surf scoters, simply can't lift their heavy bodies into the air.

The same phenomenon that is starving fur seals and sea lions--stripping the waters around the Channel Islands of the fish they love--is fattening up ducks who thrive on crunchy crustaceans, scientists believe.

The problem is certainly not life-threatening: The surf scoters will lose the weight before they migrate this summer.

In fact, the chubby ducks are not that unusual--scientists say many birds like to stuff their bellies. It's what they are dining on that is the telltale sign of El Nino.

Hundreds of thousands of Pleuroncodes planipes, or pelagic red crabs, are floating up from Baja California to the Channel Islands off the Ventura coast as a result of El Nino's unusual currents and warmer waters.

Some oceanographers say that the true indicator of an El Nino year is the return of these fiery red, inch-long critters. They have been known to travel as far north as Eureka.

Some scuba divers sighted piles of the crabs as early as January around San Nicolas Island. And less than a week ago, crew members from Island Packers, a Ventura-based tour boat company, saw dense, red patches of crabs crawling a foot deep along the shores of Anacapa Island.

The crabs are tasty to almost every kind of bird that hunts for food at the islands--only the remains of the crabs' translucent shells were left scattered among the rocks a day later.

The last time the crustaceans passed through Southern California in such large numbers was in 1992, when a lesser El Nino effect occurred, according to Dan Richards, a marine biologist at Channel Islands National Park in Ventura.

The pelagic red crabs normally are bottom-dwellers, living at ocean depths of about 300 feet. But at certain times, younger crabs will rise to the surface and float, perhaps as a way to disperse their population.

This year the warm ocean waters are whisking the crabs--also called whale feed or tuna crabs--from their tropical home off Mexico in an unusual direction: south to north.

Normally, currents during the winter off California run the other way.

"This is a classic indicator of El Nino," said Mike deGruy, a Santa Barbara filmmaker who studied invertebrate zoology. "It's textbook."

The gluttonous surf scoters just can't resist the swarm of red crabs swimming in front of their wide-open bills: They gobble them up and often swallow them whole.

Not to worry about the ducks' obesity, though.

If a surf scoter predator such as a peregrine falcon attacks, the sea fowl will duck beneath the surface and swim away. If a shark wants a bite of its succulent body, the bird's natural instinct is to get rid of its meal in a hurry, scientists say.

"They usually regurgitate what they ate if they're disturbed," said Richards.

The fat birds will shed their extra pounds as soon as the crabs disappear and the ducks begin their summer migration to Alaska.

Other classic El Nino signs already have appeared around the Channel Islands.

Thousands of California sea lions and northern fur seals have died over the last nine months because of an El Nino-related shortage of the fish they feed on. Scientists predict that virtually the entire population of fur seals and two thirds of the sea lions born in June on San Miguel Island will die by the year's end.

Rather than bringing their food supply to them, El Nino's warm waters have chased the sardines, anchovies and other fish to colder, deeper ocean waters.

Seals would happily eat red crabs--but only if the crustaceans make it to San Miguel Island. So far, experts say they have not seen the crabs travel that far west. But if they do, that would be great. "The young ones eat it like popcorn," said marine biologist Bob DeLong of the National Marine Fisheries Service in Seattle.

Boaters and biologists have noticed that pelican chicks also are dying in the wake of a series of winter storms linked to El Nino.

Although it has been hard for scientists to get out to the Channel Islands and peer into the murky ocean waters stirred up by February's storms, Jack Engle, an associate research biologist at UC Santa Barbara, began noticing drop-offs in kelp and sea stars months ago.

El Nino's warm waters have caused a massive decline of the lush forests of giant kelp encircling the Channel Islands, especially at the southeast islands of Santa Catalina and San Clemente, Engle wrote in a winter newsletter for the Channel Islands National Marine Sanctuary.

What's left of the kelp is being torn apart by this winter's storms.

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