Domoic acid poisoning from harmful algal blooms causes mass stranding events in California sea lions, creating both acute welfare emergencies and long-term neurological suffering.
Domoic acid poisoning represents one of the most severe environmental welfare crises affecting California sea lions. Acutely affected animals experience terrifying neurological symptoms including seizures, altered consciousness, and cardiac distress. Those that survive acute poisoning often develop chronic epilepsy, causing repeated seizure events that compromise welfare throughout their remaining lives. The Marine Mammal Center and partner facilities treat hundreds of these animals annually, but many cannot be rehabilitated due to permanent brain damage. Reducing harmful algal bloom frequency requires addressing the climate and nutrient pollution drivers of bloom events — a long-term challenge. In the near term, improved early warning systems and rapid response rehabilitation capacity represent the most achievable welfare interventions.