Font Resize
Fluctuating ocean conditions may be depleting the food supply of young sea lions that are turning up skinny and ill on California beaches.
Peter Wallerstein, founder and president of the Whale Rescue Team in El Segundo, has rescued 240 marine mammals along South bay beaches so far this year, including a sea lion in Redondo Beach and two other sea lions in Manhattan Beach on Friday.
"I've done more rescues this year than I have in my 25 years of doing this," Wallerstein said. "But the shocking thing isn't the number of sea lions, but the condition we're finding them in, so sick and emaciated."
While he wasn't able to say what has caused the uptick in rescues, Wallerstein said the last time he witnessed such a high rate of animals in peril was when Southern California experienced its last El Nino, the warm-water current from the tropical Pacific.
The trend, he said, will lead to many deaths this year among sea lion pups. He also cautioned beachgoers to steer clear from beached animals.
"They're hungry and they might bite you," Wallerstein said.
Scientists agree that the youngsters, born nearly a year ago on the Channel Islands off Southern California, aren't getting enough food. But they're at a loss to determine whether the sea lions' favorite foods - northern anchovies and sardines - are hard to find because they're moving south in response to falling and rising ocean temperatures.
Or scientists wonder whether
Drawing global interest is the theory that the marine mammals are signaling an early warning of an El Nino condition.
El Nino generates a spike in rain. But it would also suppress the vigorous upwelling of nutrients in the California Current, stretching from Baja California to Vancouver, needed to produce abundant krill, fish and other aquatic life.
The last big El Nino occurred in 1997-98, starving thousands of marine mammals and seabirds from a host of species along the Pacific Coast. Rain doused Northern California, heavy snow fell on the East Coast and hurricanes brewed in the Atlantic. An El Nino is overdue, scientists say.
As of Thursday, the Marine Mammal Center in Sausalito had 136 patients in its new $32 million center, which opened to the public Monday.
Of the patient load, 85 were sea lions receiving nourishment through feeding tubes and treatment for organ failure and other problems. By comparison, there were 53 sea lions under care two weeks ago.
"They're just too weak to try to forage. You can see their bones," said center spokesman Jim Oswald. So many beach reports are coming in that the center has to choose where to respond. There aren't enough trained rescue crews or vehicles to bring in - or even check on - every animal, he said.
"We believe it's food supply," said Joe Cordero, a biologist with the National Marine Fisheries Service, a department of the National Oceanic and Atmospheric Administration.
His theory is that the burgeoning California sea-lion population of 300,000 is producing so many pups that more of the yearlings are showing up on the beaches after weaning at 6 months to 1 1/2 years.
Mark Lowry, a research fishery biologist at the National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center in La Jolla, echoed Cordero's assessment.
"There was a record number of pups born last year - 59,000 - which were recently weaned. The fact that some of these weaned pups are struggling is not surprising. Not all survive to adulthood."
That could be the case, other scientists agree. But other possibilities are the fluctuating ocean temperatures, some related to global warming. Surface temperatures had remained low for most of the spring. But in recent weeks - about the time that the sea lions started showing up on the beaches - the ocean temperatures rose in the tropical Pacific from about 50 degrees to 65 degrees.
The Climate Prediction Center, run by the National Weather Service, in early June noted that sea-surface temperatures were increasing across the equatorial Pacific, and anomalies in heat content typically precede the development of El Ni o. Current observations, recent trends and some forecast models indicate that conditions are favorable for a transition to El Ni o conditions from June through August. The next forecast is expected July 9.
"The water went from being pretty cold to pretty warm in a couple of weeks. It's been spiking all over the place," said William Sydeman, a biologist and president of the Farallon Institute for Advanced Ecosystem Research in Petaluma.
Even though there isn't a full-blown El Nino, he said, predators - such as marine mammals and seabirds that feed on fish - "oftentimes will send signals."
"They'll start to respond actually before you see changes in the physical environment," Sydeman said. "They integrate everything that happens in the food web."
Staff Writer Art Marroquin contributed to this article.
