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Researchers with the University of California-Santa Cruz and the University of California-Davis confirmed an outbreak of an avian flu virus among elephant seals at Año Nuevo State Park in California, prompting park officials to cancel popular seal-watching tours for the rest of the seal breeding season. The researchers said seven seal pups tested positive for HPAI H5N1, a highly pathogenic avian influenza virus, and that additional testing results are pending for about 30 more animals.
A team from UC Santa Cruz and UC Davis made the announcement Wednesday, describing the finding as the first detected outbreak of the virus among marine mammals in California. The work followed reports of sick and dead animals that researchers said were spotted on Feb. 19 and 20, after which they collected samples for testing at the California Animal Health and Food Safety Laboratory System.
Park officials said the outbreak led them to shut down the viewing area and cancel docent-led and other guided tour programming that typically takes visitors onto parts of the seal breeding grounds, known as rookeries. Jordan Burgess, the deputy district superintendent of the California Department of Parks and Recreation, said the closures were made “out of an abundance of caution,” and officials said the goal was to prevent any spread of the disease that might be caused by people moving through areas where elephant seals are living.
Burgess also sought to differentiate the response from public-health panic. “We’re definitely not panicking about human exposure at this point,” she said, adding that officials were trying to ensure the health of both seals and people.
Christine Johnson, director of the Institute for Pandemic Insights at UC Davis’ Weill School of Veterinary Medicine, said researchers have been monitoring for signs of the disease in recent years and spotted the outbreak quickly. She said tests on samples from the initial group of animals showed infection with HPAI H5N1, and she noted that tests on samples from about 30 additional animals were still pending.
The outbreak arrives as the wider bird flu outbreak that began in 2020 has affected animals far beyond domesticated birds, spreading into wildlife across multiple regions. Researchers said the virus has led to the deaths of thousands of sea lions in Chile and Peru, thousands of elephant seals in Argentina, and hundreds of seals in New England in recent years.
Officials said they consider the virus a low risk to humans. They told visitors and local residents to avoid approaching the seals and to keep pets away from the animals, while the agencies involved in wildlife response continue monitoring at the site.
Beneath the guidance and the closures, Año Nuevo remains a key seasonal destination. Thousands of elephant seals come to the park, about 90 minutes south of San Francisco, each winter to fight, mate and give birth, drawing tourists and wildlife watchers who typically view seals from designated areas or join docent-led guided walks.
For now, officials say the viewing area is closed and tours have been canceled through the remainder of the breeding season, while university researchers continue coordinating with state and federal wildlife managers and the West Coast Marine Mammal Stranding Network to monitor the outbreak.