Avian Flu Outbreak Spreads to Marine Mammals on California's Central Coast

Outbreak at Año Nuevo State Park infects elephant seals, sea otter, and sea lion, raising concerns for entire region

Mar. 14, 2026 at 10:04am

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An avian flu outbreak centered at California's Año Nuevo State Park has spread to elephant seals, a southern sea otter, and a sea lion, with scientists confirming over 60 infected marine mammals along the Central Coast. The outbreak has led to the closure of the popular elephant seal viewing area and raised concerns about the broader impact on the region's wildlife and tourism.

Why it matters

The avian flu outbreak at Año Nuevo State Park is concerning as it has the potential to impact the entire Central Coast ecosystem, including the region's iconic elephant seal rookeries that draw many tourists. The spread to other marine mammal species like sea otters and sea lions also raises worries about the virus's ability to infect a wide range of wildlife in the area.

The details

Scientists have found about 47 dead seals, both pups and adults, along the shoreline since the outbreak began. The virus has spread to 16 confirmed elephant seals, as well as a southern sea otter and a sea lion. Experts estimate over 60 marine mammals may be infected, with the mortality rate for large male elephant seals being much higher than normal. While the risk to the general public is low, people are advised to avoid contact with sick or dead marine mammals.

  • The avian flu outbreak at Año Nuevo State Park began in mid-February 2026.
  • On March 12, 2026, scientists confirmed the virus had spread to 16 elephant seals, a southern sea otter, and a sea lion.
  • Año Nuevo State Park closed access to the popular elephant seal viewing area for the rest of the season on March 12, 2026.

The players

Patrick Robinson

The Año Nuevo Reserve director at UC Santa Cruz.

Christine Johnson

The director of the Institute for Pandemic Insights at the UC Davis Weill School of Veterinary Medicine.

Año Nuevo State Park

A California state park known for its elephant seal rookery that has been impacted by the avian flu outbreak.

Piedras Blancas Rookery

Another popular elephant seal rookery near Hearst Castle on the Central Coast.

Farallon Islands

An island chain off the coast of San Francisco where elephant seals also reside and have been impacted by the outbreak.

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What they’re saying

“We know there are more animals with signs of infection that we have sampled that are being tested across the different laboratory systems. There are likely more animals that will be updated on in the coming weeks.”

— Christine Johnson, Director of the Institute for Pandemic Insights at the UC Davis Weill School of Veterinary Medicine

“Although some mortality of weaned pups are expected, this year's mortality rate has been about four times higher compared to last year's. The death rate in large males is basically nonexistent in most years. We don't typically see large males passing away on beaches.”

— Patrick Robinson, Año Nuevo Reserve director at UC Santa Cruz

What’s next

Scientists will continue monitoring the spread of the avian flu outbreak and testing additional infected marine mammals in the coming weeks.

The takeaway

This outbreak highlights the vulnerability of California's iconic Central Coast ecosystem to emerging infectious diseases that can rapidly spread between wildlife species. It underscores the need for robust wildlife disease surveillance and the importance of protecting sensitive habitats like the Año Nuevo Reserve.