Canberra: Warming oceans are delaying the migration of blue whales, Australian experts have warned.

Karen Edyvane, a marine biologist from Australian National University, on Monday raised concerns about significant delays to the migration of pygmy blue whales past the Timor Leste coastline.

A subspecies of blue whale that grows up to 24 meters long, pygmy blue whales migrate thousands of kilometers south every year from breeding grounds off the coast of Indonesia past Timor Leste to Australian waters in October and November.

However, Edyvane told the Australian Broadcasting Corporation that she is “extremely alarmed” after not sighting any whales during the last six weeks in Timor Leste.

A former senior government scientist and member of the International Union for Conservation of Nature World Commission on Protected Areas, Edyvane attributed the delayed migration to climate change.

“What we’re seeing is major changes to the oceanography of the region, particularly in terms of upwelling strengths,” Edyvane said.

“Climate change is having an impact on the migration of the blue whale and it’s delayed the season by four to six weeks. We’re also seeing impacts on the actual health of the animals.”

It comes after Edyvane raised concerns about the health of pygmy blue whales after observing malnourished individuals during the 2022 southern migration, which she said was likely the result of warm ocean temperatures.

Australia’s Bureau of Meteorology in September declared an El Nino weather event in the Pacific.

The event is linked to hotter, drier weather in Australia but typically drives down ocean temperatures in the north, which Edyvane said should increase food supply for the whales.