Sick, Disoriented Sea Lions Are Washing Ashore Across California

The lovable sea lions that call the California coastline home are dealing with a new threat that is making them sick and disoriented. Here is a closer look at what is causing the illnesses.

California Sea Lions Suffering from Toxicosis

An alarmingly high number of sea lions are suffering from domoic acid poisoning in California. Also known as toxicosis, this condition causes sea lions to become sick, disoriented, and erratic.

According to the Marine Mammal Center, more than 100 sea lions have washed ashore and been rescued since the start of the year. The bulk of these rescues have happened since July 1. The rescue center located in Sausalito said that it has fielded between 300 and 600 calls each day from concerned citizens spotting sick sea lions.

The center recently told reporters that, "Over the past week alone, approximately 30 sea lions have been rescued in Monterey County and southern Santa Cruz County, with additional rescues occurring primarily in San Mateo, San Francisco, Marin and Sonoma counties."

Domoic acid is an algal toxin that accumulates in fish and shellfish naturally. Marine mammals can become ill after eating contaminated fish and shellfish.

The illness presents itself in a myriad of ways in sea lions, ranging from lethargy, disorientation, twitching, tremors, seizures, neurological symptoms, and erratic behavior. The most severe cases can result in permanent brain or heart damage. The veterinarians at the Marine Mammal Center are treating the sick animals with a combination of anti-seizure medication and supportive IV fluids.

What is Causing the Increase in Domoic Acid Ingestions?

In the past, marine biologists had observed an increase in these cases when certain seasonal conditions were present. For instance, cold-water years that resulted in more coastal upwelling and offshore winds tend to support the development of the algal blooms that go on to generate domoic acid.

However, scientists have noted in recent years that the toxic events are happening during times of both atypically cold and warm ocean water patterns.

The Marine Mammal Center said that it generally rescued between 75 and 90 California sea lions believed to be suffering from this type of poisoning per year in the past. This average was already hit as September began, indicating an overall trend of more sick sea lions.

Not surprisingly, the surge in infected animals has put a strain on the rescue teams. One single sea lion rescue requires the work of four to six trained experts. The impacts of the toxin on the behavior of the sea lions also present a new set of dangers.

While domoic acid poisoning has been a part of California sea life for decades, the recent surge in cases has raised concern. Scientists are now working with teams of climate scientists, algal-toxin monitoring experts, and oceanographers to determine what may be behind the increase.
 
As noted by the Marine Mammal Center, "Because domoic acid is naturally occurring, the challenge is understanding why and when conditions align to produce increasingly significant toxic events."

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