The discovery of a newborn blue whale on West Australia's south coast is a game changer", according to scientists studying the ocean giants, who say the species has no known breeding grounds in Australian waters. The juvenile was spotted with its mother just a few hundred metres off the coast near Bremer Bay, about 500 kilometres south-east of Perth, at the weekend. It may be the first blue whale born in Australian waters. Marine biologist Brodee Elsdon said the subspecies pygmy blue whales were often spotted migrating along the west coast, but rarely during this time of year, so close to shore or with a recently born calf. Pia Markovich, who was on board the vessel which spotted the pair, said the calf appeared to be very young. "Seeing a blue whale is one thing, but to have a mother and calf [is] next level," she said. "And for the calf to be so small, well that's like winning the wildlife lotto. "At first glance, puzzled passengers looked to the crew to understand the significance of this encounter. "Our faces would have said it all, jaws dropped and minds blown." Ms Elsdon said the sighting could help develop scientists' understanding of blue whale migration and breeding. There are no known breeding grounds for these giants in Australian waters. "We predict the breeding grounds for pygmy blue whale are all the way in Indonesia waters, so to have one born this early and in the Southern Ocean, changes everything we know," she said.