The University of California, Davis released on Mar. 19 a study examining the global impact of highly pathogenic avian influenza (H5N1) on pinnipeds, including seals and sea lions, and outlined recommendations for monitoring and protecting these species. The research highlights the spread of H5N1 since its discovery in Asia in 1996, noting that it has now affected every continent except Oceania, infecting millions of poultry, thousands of marine mammals, and about 1,000 people.
The study underscores the significant conservation risk posed by H5N1 to pinniped populations worldwide. According to the paper published in Philosophical Transactions B as part of a themed issue on managing infectious marine diseases in wild populations, outbreaks have killed at least 36,000 South American sea lions, 17,400 southern elephant seals, and 1,000 South American fur seals throughout Peru, Chile, Brazil, Uruguay and Argentina.
“There is a huge, unprecedented conservation risk,” said Christine Johnson, director of the Institute for Pandemic Insights at the UC Davis Weill School of Veterinary Medicine. “Influenza is constantly changing, and that is a big problem now that it’s widely circulating in birds and marine mammals.”
Marcela Uhart from UC Davis described witnessing a major outbreak among southern elephant seals in Argentina during 2023. “Southern elephant seals were the canary in the coal mine alerting us to a bigger issue of pinnipeds throughout the entire world,” said Uhart. “We can do something better to be prepared the next time before it spreads to other species.”
In California’s Año Nuevo Natural Reserve this February, northern elephant seals became the first marine mammals in the state confirmed with HPAI H5N1 due to ongoing surveillance efforts by UC Davis and partners. These preemptive measures enabled rapid detection and response when cases emerged.
Key recommendations from the study include funding long-term wildlife monitoring; strengthening communication among researchers; making wildlife health surveillance routine; improving non-invasive monitoring technologies; pursuing policy changes addressing root causes; and tackling concurrent threats such as habitat loss or climate change.
“H5 avian influenza viruses are an emergent threat to seal and sea lion populations already facing numerous conservation pressures,” said Elizabeth Ashley of UC Davis. “Understanding how this virus spreads in coastal ecosystems is critical for protecting vulnerable marine wildlife.”
The research was supported by grants from several organizations including the US National Science Foundation Center for Pandemic Insights.
