More than 100 sea lions have been sickened by domoic acid poisoning along California’s coastline in 2026, a figure already exceeding the annual average of 70 to 90 cases, according to wildlife officials. The surge in incidents, particularly severe in Monterey and Santa Cruz counties, has prompted urgent warnings from marine mammal rescue organizations.
Domoic acid, a neurotoxin produced by harmful algal blooms, has led to abnormal neurological behavior in affected sea lions, including seizures, twitching, lethargy, and disorientation. The toxin enters the marine food chain when contaminated fish such as sardines and anchovies are consumed by the animals. Wildlife experts note that sea lions, which obtain hydration solely from their food, are unable to flush the toxin from their systems, exacerbating the severity of poisoning.
The Marine Mammal Center, a nonprofit wildlife rescue organization, has reported that the current outbreak is part of a broader trend of increasing and unpredictable domoic acid cases. While such poisonings were historically seasonal, occurring primarily in summer, they are now observed year-round. Giancarlo Rulli, a spokesperson for the center, described the surge as concerning due to its unpredictability and the potential for lasting effects, including permanent brain damage in severely affected animals.
Health risks to humans remain a secondary concern, as domoic acid can also pose dangers to people consuming contaminated shellfish or seafood. However, wildlife officials have not reported any incidents of disoriented sea lions attacking beachgoers in 2026, unlike previous years when such behavior was documented.
The National Oceanic and Atmospheric Administration (NOAA) has attributed the toxin’s presence to both cold water years with strong offshore winds and warmer water years, indicating that environmental factors play a significant role in the proliferation of harmful algal blooms. The agency emphasizes that the disease is both insidious and brutal, affecting parts of the sea lions’ brains that control memory and behavior.
Wildlife experts continue to monitor the situation closely, as the surge in cases late in the summer season raises questions about the underlying causes and long-term implications for marine ecosystems.