A young humpback whale which wandered from its usual migratory route right up to Sydney’s Harbour Bridge has left the harbour.
The sub-adult whale had left the harbour, with no sign of it on Thursday, a government source told Guardian Australia.
Separately, a spokesperson for the NSW environment department confirmed “we have had no sightings today”.
The whale delighted onlookers and experts after it was first spotted swimming at Circular Quay on Wednesday morning before moving east on what experts tracking the mammal called its “full harbour experience”.
Dr Vanessa Pirotta, a whale expert on board a New South Wales Maritime boat on Wednesday, confirmed the whale was “not in distress, quite the opposite”. It appeared to be inquisitive and relaxed, visiting various harbourside locations, she said.
The whale’s appearance was a “reminder that Sydney Harbour is very wild”.
It was last seen at Rose Bay on Wednesday evening, Pirotta said on Thursday.
The founder of the citizen science project Wild Sydney Harbour, which works with organisations including the NSW government, said ordinary people who spotted the whale throughout the day helped experts know where it was. The process was “citizen science at its very best”.
There had been no sightings of the whale on Thursday to her knowledge, Pirotta said.
Pirotta said while the whale may have left the harbour, she cautioned it could resurface.
“It was just all over the place [on Wednesday]. So just when you think that it’s probably had enough, maybe it hasn’t, and maybe it could pop up where we least expect it.”
She encouraged anyone to report sightings to NSW National Parks and Wildlife Service.
The Port Authority of NSW had cameras monitoring the harbour, and they were an “incredibly important part of yesterday’s mission”, the whale expert said on Thursday.
Humpback whales usually travel the “humpback highway” which runs up and down Australia’s east coast. It is not unusual for them to briefly leave it, with four humpbacks having been seen in the harbour this migratory season.
But Pirotta said this week’s visitor was unusually explorative, coming as far as the Harbour Bridge.
