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 and caused significant losses among poultry, marine mammals, and wild birds.
The issue is important because pinnipeds have been severely affected by the virus, with tens of thousands dying across South America. The study aims to provide guidance for future surveillance efforts and policy changes to prevent further outbreaks among vulnerable species such as the endangered Hawaiian monk seal or Galapagos sea lion.
According to the paper published in Philosophical Transactions B, at least 36,000 South American sea lions, 17,400 southern elephant seals, and 1,000 South American fur seals have died due to avian flu outbreaks 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 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 in 2023: “Southern elephant seals were the canary in the coal mine alerting us to a bigger issue of pinnipeds throughout the entire world,” Uhart said. She emphasized preparedness for future outbreaks before they reach other species.
In California’s Año Nuevo Natural Reserve this February, northern elephant seals were confirmed as having HPAI H5N1 after routine surveillance set up by UC Davis with local partners detected cases quickly. Johnson called this an “exceptionally rapid detection of an outbreak in free-ranging marine mammals,” highlighting preemptive monitoring as key to effective response.
The study recommends funding long-term wildlife monitoring; improving communication between researchers; making health surveillance routine; advancing non-invasive technologies like auditory and thermal imagery; pursuing international policy changes; and addressing additional threats such as habitat loss and climate change. Elizabeth Ashley from UC Davis said: “H5 avian influenza viruses are an emergent threat to seal and sea lion populations already facing numerous conservation pressures.”
The research was supported by grants from the US National Science Foundation Center for Pandemic Insights award as well as fellowships from National Marine Fisheries Service-Sea Grant and California Sea Grant.
