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Sick Sea Lions Raise Fear of Fatal Toxin

Dozens have washed ashore in the area, and experts worry about a repeat of the domoic acid poisoning that killed hundreds in '02.

May 10, 2003|Denise M. Bonilla | Times Staff Writer

More than 30 sea lions have washed up on Los Angeles, Ventura and Orange County beaches this week, worrying scientists and marine mammal rescuers who fear another onslaught of a neurotoxin that killed more than 600 of the animals last year.

Of the sea lions that have been rescued, only 15 remain alive. They are believed to be suffering from the effects of ingesting domoic acid, a toxin produced by a species of plankton.

"We are fearful this week is an indication of what could be a terrible summer," said Jackie Jaakola, director of the Fort MacArthur Marine Mammal Care Center in San Pedro. The center has taken in 14 sea lions this week with what they believe is domoic acid poisoning.

Last year, more than 1,100 sea lions sickened by domoic acid washed ashore from Santa Barbara to San Diego County. Only 506 survived.

Domoic acid is a naturally occurring chemical produced when ocean plankton bloom. It in turn is ingested by anchovies, clams, mussels and a host of other small plankton-eating marine life. Sea lions, opportunistic feeders that munch on whatever anchovies, herring and squid come their way, absorb the toxin, which damages their brain and nervous system, causing seizures and eventually a coma.

The toxin was not discovered until the late 1980s, and scientists still don't understand why and when the algae blooms occur or how they impact wildlife. Biologists cannot predict a correlation between blooms and sea lion deaths, since the animals may feed in one area but wash up miles away. Nor does the plankton always produce the toxin.

"It just happens that a small number of them produce toxins that can harm warmblooded animals," said Gregg Langlois, a marine biologist with the state health department.

The toxin also can harm humans who digest certain shellfish. On Canada's Prince Edward Island in 1987, three people died and about 100 others fell violently ill from an outbreak of the poison in mussels. As a result, U.S. coastal states have imposed bans on shellfish fishing once a domoic acid algae bloom is detected.

Since October 2002, the entire coast of Oregon has been closed to harvesting shellfish because the toxin has been detected in clams and mussels.

In California, there have been no reported cases of humans dying from the toxin. But state health officials continually monitor coastal waters for signs of increased blooms. They said a large bloom off Palos Verdes is moving closer to shore.

In Monterey Bay in 1991, hundreds of pelicans that were acting abnormally, flying into objects and turning up dead, were among the first clues to domoic acid's effects. Since then, sea lions have been affected up and down the coast. Last year's bloom off Southern California -- which led to hundreds of sea lions stranded on the beaches of Los Angeles, Orange and Ventura counties -- was the worst so far.

"We were hoping it was just an anomaly last year, but ... we're having problems again," said Dean Gomersall, animal care supervisor for Friends of the Sea Lion Marine Mammal Center in Laguna Beach.

People who come across ailing sea lions should keep their distance and notify animal control officials or a marine mammal rescue center, authorities said.

The sea lions afflicted with the poison are almost always female and are often pregnant when the toxin starts to cause damage. Rescuers said this could be because pregnant sea lions consume a massive amount of food for their growing fetuses, concentrating greater amounts of toxin in their system. A pregnant 150-pound sea lion can consume 10% of its weight in food a day.

Rescuers said they are seeing large numbers of abandoned sea lion pups, possibly because their mothers died. More often, however, the mothers abort their fetuses or pups are still-born.

"It's very unusual to have this many young sea lions," said Gomersall, who is caring for 40 now. "Late February is usually when we see them, but we're still getting them."

Gomersall said the high number also could be attributed to storms that separate pups from their mothers.

About 250,000 sea lions live off the California coast, but it remains unclear what long-term effect domoic poisoning will have on the animals.

"That's the $64,000 question that no one can really answer," said Dr. Richard Evans, medical director for the Laguna Beach center. "The sea lion population is robust to say the least, but when you lose the mother and the second generation, it has a logarithmic effect on the population."

Rescue workers are fielding dozens of calls a day and are bracing themselves for tough months ahead. Many of the centers rely on volunteers and donations, and the doubling of case loads can lead to soaring budgets and overworked staff. Each sea lion weighs 150 to 200 pounds, requiring three or more people just to lift it. Many sea lions are having seizures and lashing out violently. Others are in comas, requiring constant monitoring and care.

Scientists have been performing autopsies on sea lions afflicted with domoic poisoning and have witnessed mass deterioration of the hippocampus, the part of the brain responsible for memory.

"It's gruesome," said Evans. "I've never seen something destroy the hippocampus that badly."

On Friday, center workers had to euthanize four sea lions, including a 160-pound female found Tuesday near Huntington Beach that they named Hannah. After being given a sedative, Hannah was injected with a large dose of barbiturates. The ailing animal, who spent three days lying flaccid on the floor of her cage, not even stirring while workers stepped over her, gave out a few last waves of her black flippers, then died.

"It's really terrible because there's nothing we can do for them," Evans said. "It's such a shame to see these beautiful sea lions die."

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