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On Common Ground: How to aid disoriented, ill sea lions

California sea lions in Malibu are falling victim to what appears to be domoic acid toxicity, a condition caused by ingesting a microscopic diatom called Pseudo-nitzschia australis. Photo Submitted
Mike Remski, Marine Mammal Program Manager, California Wildlife Center
7:14 am PDT April 25, 2017

If you’ve visited the Malibu shoreline this April, it’s likely that you have encountered a large California sea lion at the water’s edge. 

And if you’ve watched this animal staring into the sky, or laying in the shore break and thought to yourself, “something doesn’t seem quite right,” you would be correct. Many of these animals are displaying symptoms suggestive of domoic acid toxicity.

Domoic acid is a naturally occurring neuro toxin produced by certain types of algal blooms, specifically by a microscopic diatom called Pseudo-nitzschia australis. And although sea lions do not ingest the toxic algae directly, filter feeding fish such as sardines do. Sea lions, of course, feast on these fish, and the more fish they eat, the more toxin they ingest. 

Recently large algal blooms producing this toxin have been identified in local and nearby waters, and has coincided with the stranding of dozens of California sea lions. The majority of affected sea lions being observed are adult female California sea lions, probably since these are the animals eating the greatest share of these fish, in preparation of hauling out to give birth within the next few months. These animals suffer from symptoms ranging from disorientation and confusion, to seizures and even death in more severe cases.   

Marine mammal rehabilitation centers up and down the coast are being pushed to capacity by the influx of these patients. And although there is no “cure” for these ailments, rehab centers can at least provide a safe place for the animal to rest and hopefully purge the toxins.  

Long-term effects of domoic acid toxicity are still largely unknown, but outcomes seem to be greatly dependent on the amount of toxins ingested by the animal.

If you encounter a sea lion on the beach, always give the animal plenty of space. Whether the animal is sick or not, their behavior can be unpredictable, and they can inflict a severe bite. 

All marine mammals are federally protected, and harassment (causing them to alter their behavior) is strictly prohibited. A good rule of thumb is that distance of 50 feet between yourself and the animal is a minimum safe distance.  

Notify the California Wildlife Center at (310) 458-9453 if you encounter marine mammals hauling ashore along our Malibu beaches. Although some may just be coming ashore to rest or warm up, others may be in need of help, and it’s not always easy to tell the difference. A rescue team will be sent out to assess the animal’s condition, and depending on available room at local rehab centers, the animal may be taking in for further observation and treatment.

On Common Ground is a monthly column written by various California Wildlife Center employees. CWC, a nonprofit located in Calabasas, cares for injured wildlife in Malibu and beyond.