Domoic Acid Poisoning Suspected in Sea Lion Wandering Highway 37

The Marine Mammal Center rescued a California sea lion along Highway 37 near Sears Point Raceway. Upon arrival to the scene it was determined that the animal had previously been in rehabilitation at the center and treated for malnutrition and poor stranding locations. The sea lion is a juvenile male named School Daze. (Credit © The Marine Mammal Center)

Another wayward pinniped visited Highway 37 this week, causing traffic to grind to a halt by Tuesday morning. It was near the stretch where traffic snarled in December when a 900-pound elephant seal tried to cross the road.

The disoriented explorer this time was a young, not-fully-grown sea lion known to authorities as School Daze: an animal that has been treated twice at the Marine Mammal Center in Sausalito for malnutrition. Most recently, he'd been nursed back to a healthy weight of about 80 pounds and released at the Farallon Islands in January.

"And now he has shown up again, sadly and disturbingly underweight," says Jeff Boehm, executive director at the Marine Mammal Center. Since his release, School Daze has lost about 10 pounds. "This gives us pause and makes us wonder what might be going on beyond malnourishment."

School Daze was weighed, sampled, poked and prodded in a series of exams aimed at assessing the young sea lion's health and finding clues to his odd behavior.

"One of our suspicions is that there might have been exposure for this animal, either in utero or when nursing from its mom, to the toxin domoic acid," Boehm says.

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That's the toxin that shut down most of commercial Dungeness crab season this year. Acute exposure to domoic acid can cause seizures, which veterinarians haven't seen in School Daze. At lower levels of exposure, the toxin can cause problems in thinking and navigation.

"The red flag for us with this little guy is that he keeps showing up in odd places," Boehm says.

Domoic acid occurs naturally in algal blooms. This year's bloom was far larger than normal because of exceptionally warm waters. The Marine Mammal Center estimates it has treated 235 animals affected by domoic acid.

Typically, staff and volunteers treat a handful of isolated incidents each year. But recently, they've seen scores of distressed animals up and down the coast, including elephant seals, harbor seals and sea lions.

School Daze is one of 220 animals, including about 80 sea lions, at the center right now. That's four times the number of sea lions they normally care for, says Boehm.

"We find ourselves in the fourth year of a crisis with not just sea lions, but marine mammals on our coast," Boehm says.

Besides the domoic acid problem, there's also a food problem. Marine mammals rely on calorie-rich cold-water fish like anchovies and sardines. But populations of sardines in particular have fallen over the past decade.

It is perhaps fortunate for School Daze then that his days of swimming on an empty stomach are likely over. Marine Mammal Center veterinarians do not think he should be released into the wild again. Not only is he prone to wrong turns, but he seems to have lost the inhibitions and independence animals need to take care of themselves.

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The Marine Mammal Center is planning to work with NOAA Fisheries to find School Daze a permanent home in a zoo, aquarium or other facility.

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