Seven Elephant Seal Pups Test Positive for H5N1 in California
Seven weaned northern elephant seal pups at Año Nuevo State Park in San Mateo County have tested positive for highly pathogenic avian influenza (HPAI) H5N1. The cases mark the first confirmed detection of the virus in a marine mammal in California and the first known detection in northern elephant seals.
What Researchers Are Seeing at the Año Nuevo Colony
Researchers monitoring the well‑known elephant seal colony first observed abnormal respiratory and neurological symptoms in several seals, including weakness and tremors. Samples collected from sick and deceased animals were tested by veterinary laboratories, where avian influenza was confirmed.
Why Año Nuevo Is Closely Monitored
Año Nuevo State Park hosts one of the most closely studied northern elephant seal colonies in the world. Thousands of seals gather there during the winter breeding season, and scientists from the University of California have been monitoring the population for decades. The long‑term research presence allows scientists to quickly identify unusual health events and track potential impacts to the population. 
Public Access and Wildlife Safety
In response to the outbreak, public access to seal viewing areas has been temporarily closed and guided elephant seal tours have been canceled for the remainder of the season while wildlife officials continue to assess the situation.
While the risk to the general public remains low, wildlife officials advise visitors not to touch live or dead marine mammals and to keep pets well away from wildlife. Maintaining distance helps protect both people and animals and reduces stress on sick wildlife.
Monitoring the Situation Along the California Coast
Scientists and wildlife agencies are continuing to monitor the colony and other marine mammal populations along the West Coast. Surveillance efforts are helping researchers understand how the virus may be spreading among wildlife and what it could mean for marine ecosystems.
