Scientists Warn Bird Flu Could Cause 'Carnage' for Endangered Australian Sea Lions

Threat to Endangered Population

Scientists have warned that the H5N1 bird flu virus could cause "carnage" for Australia's endangered sea lion and seal populations. The Australian sea lion is particularly vulnerable, with only approximately 12,000 individuals remaining in the wild. The species has already seen its population decline by 60% over the last four decades.

Alexia Wellbelove, campaign director for the Australian Marine Conservation Society, stated that the population is too small to absorb the types of losses bird flu has inflicted on marine mammals in other regions. "Every colony, every pup, every individual matters when a population is this small," Wellbelove said.

Evidence of Local Transmission

Federal authorities confirmed 54 cases of H5N1 bird flu in wild seabirds across mainland Australia as of August 2, 2026. This figure nearly tripled in less than 24 hours. In South Australia, five infected terns were confirmed at Seal Bay, a critical breeding site that is home to roughly 5% of the global population of the species.

The virus has also been detected in other marine mammals. The first positive case of the virus in a mammal was confirmed in a long-nosed fur seal at Beachport, located 300km south of Adelaide. Additionally, a suspected case was recorded in a long-nosed fur seal at The Pages Conservation Park, an area that serves as a haven for the endangered Australian sea lion.

Global Precedents and Risks

The urgency of the warning stems from catastrophic losses observed in other regions. According to Wellbelove, the virus killed 30,000 sea lion pups in South America within six months of transmission from birds to mammals. On Heard Island, the virus killed more than 13,000 elephant seal pups in a single season. In some areas, the virus is estimated to have killed 95% of elephant seal pups.

Scientists believe seals are particularly susceptible because they frequently share coastal habitats with infected seabirds and haul out in tightly packed colonies, which allows disease to spread quickly. For the endangered Australian sea lion, experts warn that even relatively small outbreaks could have significant conservation consequences.

Biological Factors and Survival

The Australian sea lion has historically struggled to recover from populations losses caused by fur hunting. This is attributed to a unique breeding cycle where mothers do not wean their pups until they are 18 months old.

However, some researchers believe this unique biological trait may offer a layer of protection against the virus. Dr. Gray noted that unlike other pinnipeds, Australian sea lion pups are not born at a site over a distinct, short period of time, but rather over an extended period. This dispersion may prevent a single viral hit from wiping out an entire season's pup population.

Response and Public Guidance

In response to the threat, James Johnston, a senior advocate for the Invasive Species Council, has called for critical emergency wildlife funds to give wildlife a better chance of surviving the outbreak.

Authorities have issued guidance to the public to avoid touching sick or dead birds or marine mammals. Citizens are instructed to record the location and take photographs from a safe distance, keep pets away, and report sightings to the Emergency Animal Disease Hotline.