Why do more than 100 killer whales gather in Western Australia every year?

A researcher at Flinders University finally figured out why a large number of killer whales gather at a major spot on the southern coast of Western Australia every summer

In a new paper published in "Deep Sea Research," Associate Professor Jochen Kampf, a physical oceanographer, described the migration of killer whales to the continental slope near Bremer Bay in the Gulf of Western Australia from late spring to early autumn (January to April) in Antarctica.

"This gathering is related to the local marine food," Associate Professor Kampf said: "In an enclosed area near the seabed plateau near the top of the Hood Canyon, a net of benthic particulate organic matter (POM) is upwelling

But how and why does this feeding gathering happen?

Detailed modeling of three submarine canyons in the area has demonstrated how this process is beneficial to Hood Canyon rather than the adjacent Bremer Canyon and Whale Canyon

"We showed that the Hood Canyon on the continental slope enables it to transport more benthic particles to the surrounding area, which is supported by smaller-scale fluctuations that cause the upwelling of the POM

Whale watching is a popular activity at the hotspot of Bremer Bay Canyon, located 70 kilometers off the shore of Bremer Bay in Fitzgerald River National Park

The naturalist Charters Whale Watching in Bremer Bay said that several years of eco-wilderness expeditions discovered more than 275 common killer whales at the site from January to April.

"This kind of large killer whale gathering area in Bremer Bay comes to the same enclosed area every year on the submarine plateau near the top of the Hood Canyon, where the total water depth is between 800 and 1,000 meters

The hydrodynamic model framework of the "Oka Plateau" explains how the Hood Canyon produces a concentrated flow of polyoxymethylene in a deep place, which provides food for deep-sea crabs, squid and other filter-feeding animals preyed by killer whales

"Explaining the feeding aggregation of these populations is an important step in explaining this natural phenomenon, he said

The Naturalist Charter website says: "Every summer, this newly discovered remote ocean wilderness hot spot far from the coast of the Wa State becomes a center of incredible life-strength, including whaling sharks, giant squids, sperm whales, a large number of seabirds and the largest in the southern hemisphere.

Journal Reference :

1. Jochen Kämpf.