- Avian influenza, also known as avian influenza, is causing significant mortality in seals and sea lions around the world.
- The 2020 avian influenza epidemic caused mass mortality in domestic birds and has now spread to wild animals around the world.
- Seals and sea lions have increased susceptibility to the virus, especially in areas such as Maine and Chile.
Bird flu has killed tens of thousands of seals and sea lions in various parts of the world, disrupting ecosystems and baffling scientists who have no clear way to slow the devastating virus.
The global bird flu outbreak that began in 2020 has killed millions of domestic birds and spread to wild animals around the world. Although the virus is not considered a major threat to humans, its spread to agricultural operations and wild ecosystems has caused widespread economic disruption and environmental damage.
Scientists say seals and sea lions living in far-flung places like Maine and Chile appear to be particularly susceptible to the disease. The virus has been detected in seals on the east and west coasts of the United States, killing more than 300 seals in New England and several more in Washington state’s Puget Sound. The situation is even more dire in South America, where more than 20,000 sea lions have died in Chile and Peru, and thousands of elephant seals have died in Argentina.
A goat in Minnesota tests positive for bird flu, becoming the first case in the United States.
Although the virus can be controlled in domestic animals, it can spread uncontrollably in wild animals, devastating marine mammals such as seals in South America that had not been previously exposed to the virus, Karen said.・Marcela Uhart, head of the C Center’s Latin America program, said: Dreyer Wildlife Health Center at the University of California, Davis.
A gray seal swims in Casco Bay off the coast of Portland, Maine, on September 15, 2020. Bird flu has killed tens of thousands of seals and sea lions in various parts of the world, disrupting ecosystems and baffling scientists who have no clear way to slow the devastating virus. (AP Photo/Robert F. Bucati, File)
“Once a virus enters a wild animal, it spreads like wildfire as long as there are susceptible animals and species,” Woohart said. “The movement of animals spreads the virus to new areas.”
Scientists are still investigating how the seals contracted bird flu, but Uhart said it was most likely through contact with infected seabirds. Marine mammals in South America have been consistently affected with high mortality rates since the virus arrived in late 2022, and the virus has killed hundreds of thousands of birds in Peru and Chile since then, he said. pointed out.
Bird flu outbreak in Antarctica, scientists announce first bird flu outbreak on mainland China
The virus is still spreading, with the first confirmed case in mainland Antarctica in February.
The death of seals and sea lions disrupts ecosystems in which marine mammals act as major predators near the top of the food chain. Seals help maintain balance in the ocean by preventing overpopulation of the fish species they feed on.
Although populations of many affected species, such as southern deer and southern elephant seals, are relatively stable, scientists are concerned that the virus could jump to more at-risk animals. There is. Scientists say bird flu may have played a role in the deaths of hundreds of endangered Caspian seals in Russia last year.
“Wildlife declines at the current scale pose an unprecedented risk of depleting wild animal populations and creating an ecological crisis,” the intergovernmental organization World Organization for Animal Health said in a statement. Stated.
In New England, scientists at Tufts University Cummings School of Veterinary Medicine found that an avian influenza outbreak that killed more than 330 harbor and gray seals along the North Atlantic coast in 2022 was worse than initially thought. I discovered that. Scientists reported that the seals may have contracted the virus from the gulls by coming into contact with their feces or by preying on infected birds.
The U.S. government has determined that the seal die-off was an “unusual mortality event” caused by avian influenza. Although the National Oceanic and Atmospheric Administration declared the event over, concerns remain about its possible recurrence.
“Marine mammals remain fairly unique in the scale of the outbreaks that are occurring,” Tufts study author Wendy Puryear said. “One of the connections is that there are a lot of viruses circulating among coastal birds, and there’s a lot of opportunity for those wild birds to host the viruses and transmit them to marine mammals.”
Some scientists and environmentalists say there may be a link between the outbreak and climate change and ocean warming. Rising sea temperatures off the coast of northern Chile are reducing the number of fish they feed on, making the sea lions weaker and more susceptible to disease, said Liesbeth van der Meer, director of Chilean environmental group Oceana. Ta.
Scientists and environmentalists are hopeful that vaccinating poultry will reduce the spread of the disease, Van der Meer said, and also encourage people to avoid potentially infectious animals in the wild. He added that it was important.
“Authorities are running a campaign on this disease and strongly recommending people not to approach seabirds and marine mammals that exhibit symptoms or have been found dead in coastal areas,” van der Meer said. said.
Even seals in aquariums are not considered completely safe from avian influenza. The New England Aquarium, whose outdoor harbor seal exhibit entertains thousands of visitors each year, has taken strict hygiene measures to prevent the spread of the virus to the animals, said Melissa Jobron, director of animal health at the Boston Aquarium. He said there was.
She said staff are not allowed to bring backyard poultry products into the aquarium, and the seal exhibit is protected by shade from birds that could carry the virus.
“We know it’s a risk to the animals that live here,” Jobron said, adding that no seals at the aquarium have been infected.
Avian influenza: disease symptoms and impact on birds and humans
Mutations in avian viruses are making marine mammal deaths even more alarming, according to a paper published in Nature Communications last fall. The mutation “requires further investigation and highlights the urgent need for active community surveillance to manage the outbreak and limit its spread to other species, including humans,” the study said. Says.
Another study published in February in the journal Emerging Infectious Diseases found that the avian influenza virus is adapted to spread between birds and mammals. Researchers found nearly identical virus samples in dead sea lions, dead seals, and dead seabirds. They said the discovery was important because it confirmed an outbreak in multiple species that could affect marine mammals and birds.
More seal deaths could disrupt critical ecosystems around the world, said Linda, executive director of Maine Marine Mammals, a marine mammal conservation group that responded to seals with avian influenza during the New England outbreak. Doty said.
“We need this happy ecosystem. If we’re killing some important species, what’s the trickle-down effect of that? That’s the million-dollar question,” Doughty said. said.
