Fears for elephant seals as bird flu kills half of population in South Atlantic | Bird flu

Avian flu has wiped out half of South Georgia’s breeding elephant seals, according to a study that warns of “serious implications” for the future of the species.

This isolated island in the South Atlantic Ocean is home to the largest population of southern elephant seals in the world. Researchers estimate that 53,000 females will die from bird flu in 2023.

The population has now fallen by 47%, according to researchers. “It was a pretty grim number,” said lead author Connor Bamford of the British Antarctic Survey in Cambridge. “I didn’t expect it to be this high.”

In 2024, tourists on cruise ships reported that the tomb of explorer Ernest Shackleton had become inaccessible to visitors due to “dead seals blocking the way”. But Bamford said it was likely many of the dead animals were never seen, having returned to the sea when sick to cool off.

It is possible that direct losses from avian influenza were exacerbated by the physical stress of females abandoning their young.

“We knew there was a high level of mortality – well above normal levels – but it wasn’t until we had this before and after comparison that we could see how widespread it was,” Bamford said. In the long term, he said, it would have a “dramatic impact on the population”.

The South Atlantic island is home to 54% of the world’s breeding population of elephant seals. The team used aerial images of three beaches to compare the breeding population in 2022 versus 2024, according to the paper published in the journal Communications Biology.

There was a particularly high level of mortality among the young, and females take three to eight years to begin reproducing.

“A colleague of mine is on a boat right now, and this year the number is lower than last year. That suggests the virus is circulating in the population,” Bamford said. “I wouldn’t say it’s over at all.”

Research suggests that bird flu continues to spread among Antarctic bird and mammal species.

“The apparent loss of nearly half of the female breeding population has serious implications for… future population stability,” the researchers said in the paper. “These results highlight the urgent need for continued and intensive monitoring. »

The current highly pathogenic H5N1 strain of avian influenza was initially detected in Europe, before spreading across the Americas. It reached South Georgia in 2023, but its impact took time to calculate due to the remoteness of the islands.

“The results of this study are heartbreaking,” said Professor Ed Hutchinson, a virologist at the University of Glasgow, who was not involved in the study.

“It is unclear how severe the impact of this virus will be on other Antarctic and sub-Antarctic mammal and bird species,” he said. “All we can do is wait and watch.

“H5N1 has already had devastating impacts on ecosystems around the world, from seabird colonies in the UK to sea lions in South America. We will soon find out what this will mean for Antarctica.”

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