The whales were spotted off Curl Curl Beach during a tour by a Whale Watching Sydney boat on Thursday.
“I have never seen killer whales off Sydney before,” said whale expert Dr Vanessa Pirotta from Macquarie University.
Whale Watching Sydney said in a social media post:“There was a frenzy of activity and the orcas buzzed past the boat in formation,while chasing the humpbacks.”
“The humpbacks were closing in together and we assume they may have been protecting a calf,but it’s hard to tell with such a flurry of excitement.”
Pirotta said it was common for orcas to prey on juvenile humpbacks on Australia’s west coast,but it was rarely seen in eastern waters.
“The fact that we’re seeing that is really interesting because that’s direct evidence that we might start seeing similar behaviour to what killer whales do on the west coast,” she said.
Pirotta said the sighting was a great opportunity for science to gather information about orca behaviour on the east coast.
Pirotta described the rare spot as an “opportunity sighting”.
“You never know your luck when you head out on the sea.
“I’m really excited.”
Whale Watching Sydney said it had not spotted orcas in Sydney’s waters since a sighting at Botany Bay in 2018.
“We feel so lucky to have had such an amazing experience today,” it said in the post.
The sighting comes a week after authorities entangled in fishing line in Sydney Harbour almost 24 hours after it was first spotted.
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