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

Biologists have finally fathomed why large numbers of killer whales gather at a single main location off the Western Australian southern coastline every summer. A physical oceanographer describes the conditions which have produced this ecological natural wonder of orcas migrating to the continental slope near Bremer Bay in the western Great Australian Bight from late austral spring to early autumn (January-April).