H5N1 Avian Flu Confirmed in Northern Elephant Seals at Año Nuevo; Park Closes Viewing Areas as Testing Expands
Highly pathogenic avian influenza H5N1 has been confirmed in northern elephant seals at Año Nuevo State Park, California, prompting closure of seal viewing areas and canceled guided tours as testing expands and agencies increase coastal surveillance.
Key takeaways
- H5N1 detected in northern elephant seals: several weaned pups tested positive and dozens of deaths were reported during early response efforts; sources include DVM360, Mongabay, CIDRAP, and California State Parks.
- Rapid testing and confirmation: samples collected Feb. 19–20 were screened at UC Davis labs and confirmed by the USDA NVSL, aiding a swift response.
- Precautionary closures: Año Nuevo closed public seal viewing areas and canceled guided tours for the remainder of the season to limit spread and protect people and animals.
- Expanded coordination: UC Davis, UC Santa Cruz, NOAA Fisheries, California Department of Fish and Wildlife and the West Coast Marine Mammal Stranding Network are coordinating surveillance and necropsies.
How the outbreak was found and confirmed
Field scientists from UC Santa Cruz observed unusual signs in multiple seals on Feb. 19–20 — breathing difficulty, weakness, tremors, seizures and sudden deaths. Samples from sick and deceased animals were sent for testing to the California Animal Health and Food Safety Laboratory System at UC Davis, and initial screening returned positive for avian influenza. The diagnosis was subsequently confirmed as highly pathogenic avian influenza H5N1 by the USDA National Veterinary Services Laboratory.
Early media and agency reports noted roughly 7 initially confirmed pups, with later updates indicating as many as a dozen positives and reports of dozens of deaths during the early response period.
Sources reporting these steps included California State Parks, Mongabay, and public field notes documented in the AFLU Diary.
Why surveillance mattered at Año Nuevo
Año Nuevo hosts roughly 5,000 northern elephant seals in winter, with about 1,350 on the beach when the outbreak began. The colony — monitored individually by UC Santa Cruz for ~60 years — gave researchers rare, long-term datasets that enabled fast, individual-level detection.
Increased monitoring by UC Davis and the NSF Center for Pandemic Insights, plus routine testing of marine birds and mammals since 2024, allowed for rapid collection and testing once unusual signs appeared. Scientists including Christine Johnson of UC Davis praised the early detection and cross-institution coordination (California State Parks, Mongabay).
Broader context: H5N1 in marine mammals worldwide
H5N1 has been circulating globally since 2020 and has infected numerous bird and mammal species. Large die-offs of southern elephant seal pups and other marine mammals in South America in 2023–24 highlighted the threat and motivated heightened coastal surveillance in North America. The California detection underscores concerns about H5N1 moving into marine mammal populations (Mongabay, CIDRAP, The Marine Mammal Center).
Public health risk and safety guidance
Officials say the risk to the general public is very low, but not zero. HPAI can move between animals and, in rare cases, to people. Public health guidance emphasizes:
- Do not touch live or dead seals or birds;
- Avoid handling sick or injured wildlife;
- Keep pets away from seals and birds to reduce transmission risk.
If you find a sick, injured or dead marine mammal in California, Oregon or Washington, call the NOAA Fisheries West Coast Region Stranding Hotline at (866) 767-6114. Do not attempt to move or care for wild animals yourself (California State Parks, AFLU Diary, UNMC).
Local closures, tourism effects and park actions
California State Parks closed public access to Año Nuevo seal viewing areas and canceled guided elephant seal tours for the rest of the season beginning Feb. 23 as a precaution to reduce human contact and slow potential spread. These guided walks are a key local tourism draw; closures may create short-term economic effects for nearby rural towns, seasonal workers, and small businesses.
Coordination and ongoing response
Teams from NOAA Fisheries, California Department of Fish and Wildlife, the West Coast Marine Mammal Stranding Network, UC Davis, and UC Santa Cruz are coordinating surveillance, testing and necropsies. UC Davis is testing birds and marine mammals along the California coast — from Sonoma to San Luis Obispo counties — to determine the scope and movement of the virus (California State Parks, AFLU Diary).
Scientists noted cautious optimism: many adult females had already migrated when the outbreak began, which may limit widespread adult mortality. However, long-term effects on pup survival and population dynamics will require months or years of monitoring and study.
Implications for the United States
Economic: Coastal tourism and small businesses near Año Nuevo and similar sites could see short-term visitor declines. Guided tours, local retail and lodging may experience lost revenue during the viewing season (Mongabay).
Policy: Wildlife-health programs may face pressure for sustained surveillance funding and enhanced stranding response capabilities. The event could prompt coastal lawmakers and federal agencies to revisit zoonotic preparedness plans (CIDRAP).
Social and cultural: Clear, transparent communications and well-defined reopening criteria are important to balance public access, community livelihoods, and wildlife protection during temporary closures.
Practical steps for residents and visitors
- Do not touch live or dead seals, birds, or distressed wildlife.
- Keep pets leashed and away from beaches where marine mammals gather.
- Report sick, injured or dead marine mammals to the NOAA Fisheries West Coast Region Stranding Hotline at (866) 767-6114.
- Follow updates from California State Parks and local health departments for reopening and test results (California State Parks).
Reporting and sources
This article draws on agency releases, laboratory confirmations and reporting by multiple organizations. Key sources and links:
- California State Parks news release
- DVM360
- Mongabay
- CIDRAP
- The Marine Mammal Center
- AFLU Diary
- InsideClimate News
- UNMC
“Do not touch or attempt to care for wild animals — report concerns to authorities and let trained responders handle testing and recovery.”
