Orca-nising: Researchers find killer whales congregate in three key Australian locations

Researchers from Flinders University have discovered that killer whales in Australia tend to congregate in three distinct areas, which supports the theory that there are two types of killer whales: temperate and tropical.

A pod of southwestern Australia killer whales travelling across the Bremer Sub-basin. Picture: Rebecca Wellard (Project Orca).

Researchers from Flinders University’s Cetacean Ecology, Behaviour and Evolution Lab (CEBEL) have modeled the distribution of killer whales (Orcinus orca) in Australian waters.

In a study published in the scientific journal Ecology and Evolution, researchers tracked 1310 sightings of orcas around the country in the past four decades.

The species distribution model found the orcas liked to gather in Bonney Upwelling (South Australia/Victoria), Bremer Sub-basin (Western Australia), and Ningaloo Reef (WA).

Researchers have mapped killer whale distribution over the last 40 years. Picture: Flinders University

“Not only now do we have a nationwide picture, but our findings also support the idea that at least two ecologically distinct forms of killer whales exist in Australia – a temperate and a tropical form,” said lead author of the article Marissa Hutchings.

The research calls for stronger conservation measures to protect these unique populations, “particularly given their role as apex predators in the marine ecosystem and the fact that some of their most important habitats are currently only partially protected by legislation,” she said.

A northwest Australia killer whale captured on Ningaloo Reef. Picture:John Totterdell (CETREC WA).

Another author on the paper, Flinders University Associate Professor Guido Parra, said differences in range and drivers of occurrence are important to recognise because anthropogenic stressors such as commercial fishing, marine tourism, offshore drilling, and chemical pollutants are becoming increasingly prevalent in Australia.

“We hope this study will help inform the conservation of this species, which is still considered data deficient and remains to be adequately protected under Australian Government legislation," said senior author Luciana Möller.

The study complements ongoing research into the genetics, feeding ecology and diversification of Australia’s killer whale populations.