Australia probes sharp drop in humpback whale sightings after census raises concerns

Australian marine scientists are investigating an unexpected decline in humpback whale sightings after an annual census recorded a sharp drop in numbers along the country's southwest coast, raising fresh questions about the population's health and migration.

The annual whale census conducted by the Organisation for the Rescue and Research of Cetaceans (ORRCA) recorded just 22 humpback whales passing Cape Naturaliste in Western Australia this year, down from 69 in 2025 and 62 in 2024, Australia's public broadcaster ABC reported.

Researchers described the roughly 60% decline as highly unusual.

Capri Jolliffe, chair of the Geographe Marine Research group, told ABC scientists would normally expect annual fluctuations of around 20%, making this year's decline "quite alarming."

Researchers are examining possible factors, including changes in food availability, delayed migration patterns and disease, though no single cause has been identified.

The findings come days after reports of several whale deaths along Australia's coastline, adding urgency to calls for further investigation into the health of migrating whale populations. Scientists have urged systematic testing of stranded whales to determine whether disease or environmental factors are playing a role.

Whale-watching operators have also reported significantly fewer humpback sightings this season.

Paul Cross, who has operated whale-watching tours in Western Australia for 17 years, told ABC it was the poorest start to a season he had witnessed, with whale numbers and behavior differing noticeably from previous years.

Western Australia's Department of Biodiversity, Conservation and Attractions said migration timing can vary from year to year and stressed that it had not yet seen evidence of a broader population decline.

ORRCA's annual census on Australia's east coast recorded more than 1,950 whales during their northern migration, although organizers said changes to the survey methodology meant the figures could not be directly compared with previous years.