ADELAIDE / RankWire.AI / – South Australian authorities confirmed the death of an endangered Australian sea lion caused by H5N1 avian influenza. A park ranger found the carcass at Seal Bay on Kangaroo Island. This island hosts the third-largest single colony of the species, making up about five percent of its total population. The first bird flu-related death of an Australian sea lion occurred on Kangaroo Island, prompting wildlife officials to step up surveillance around key pinniped breeding sites.
Official reports from the South Australia Department for Environment and Water confirmed laboratory tests showed a strong positive for H5 avian influenza. Environment Minister Emily Bourke explained that the sea lion had been recovering from a shark wound sustained three months prior. However, post-mortem diagnostics revealed that the viral infection was the main cause of death. Bourke added that the sea lion’s weakened immune system during recovery likely increased its susceptibility to the virus.
This event raises serious concerns for the species, which is found only in Australia. Its global population is estimated between 10,000 and 12,000 individuals. About 80 percent of these animals live in South Australia. Prior to the virus’s arrival, colonies along the coast were already experiencing an annual decline of roughly two percent.
Australian Sea Lion’s First Fatality from Bird Flu on Kangaroo Island
Following the case, wildlife managers in the state launched targeted measures at Seal Bay. Over 400 sea lion pups received hookworm treatments to support their immune health. Feral cats were trapped to reduce transmission risks around the colonies. Bird flu’s first known death of an Australian sea lion on Kangaroo Island prompted collaboration with the Australian Department of Agriculture, Fisheries and Forestry. They are exploring involvement in international trials for experimental vaccines for mammals.
This case indicates the spread of H5N1 among Australian marine mammals. Previously, a long-nosed fur seal tested positive at Beachport on the Limestone Coast. Researchers from Charles Darwin University warned about potential mortality events for local seal populations. Similar mass die-offs have been reported among pinnipeds in South America and the sub-Antarctic regions.
Biosecurity Measures Enforced in Coastal Reserves
More than 290 cases of H5 avian influenza have been confirmed in wild birds and mammals across South Australia. This accounts for over half of the total cases across the country. Authorities reported no new sea lion deaths at Seal Bay, but officials remain vigilant.
Wildlife agencies continue daily surveillance on islands and mainland sites. They monitor disease spread, mortality rates, and implement biosecurity protocols. These efforts aim to protect vulnerable marine species. Updates and guidelines are available on official government environmental websites as health teams work to safeguard these animals.