WASHINGTON (dpa-AFX) - Seven recently weaned elephant seal pups at Año Nuevo State Park in California have tested positive for the highly pathogenic avian influenza (HPAI) H5N1 virus, according to confirmation from the U.S. Department of Agriculture's National Veterinary Services Laboratory.
Año Nuevo State Park, located in Pescadero, is home to one of the largest mainland breeding colonies on the U.S. West Coast. Each winter, nearly 10,000 northern elephant seals arrive at its shores for breeding and pupping. This newly confirmed outbreak represents the first known instance of HPAI H5N1 infecting marine mammals in California, as well as the first documented case in northern elephant seals. The development has raised concern among scientists, especially after a similar strain caused severe mortality among southern elephant seals in Argentina in 2023.
The issue first came to light on February 19 and 20, when a research team led by marine ecologist Beltran observed several seals showing unusual symptoms such as breathing difficulties, weakness, and signs linked to respiratory and neurological distress. Samples collected from both sick and deceased animals were sent to the University of California, Davis for analysis at the California Animal Health and Food Safety Laboratory System. Initial tests identified avian influenza, which was later confirmed by federal authorities as the H5N1 strain.
In response, scientists are now collaborating with agencies including NOAA Fisheries, the California Department of Fish and Wildlife, and the West Coast Marine Mammal Stranding Network to monitor marine mammal health along the coastline and track any further spread.
As a precaution, park authorities have temporarily closed public access to seal viewing areas until March 1 to allow wildlife health experts to assess the situation. Generally, guided tours are offered during the pupping season, which runs from December through March, while visitors can observe the animals freely between April and November.
Officials have announced that visitors affected by the closure will receive full refunds. Meanwhile, a live webcam operated by California State Parks will continue to provide virtual access to the annual gathering of elephant seals on the beach.
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