The orca calf that captured the country's heart with its struggle to survive has been buried on an island overlooking the ocean where wild orca frequent.

The calf died in the early hours of Saturday despite a big effort to save it after it was found in Tauranga Harbour nuzzling a buoy for comfort.

Orca rehabilitation experts, including Dr Ingrid Visser and US expert Jeff Foster, had been brought in to try to save the calf, which had been transferred to a pool to receive medical treatment.

The calf known by various names such as Bob, Tama, Ongare and Tiger, died at 4.15am on Saturday in the arms of his carers, the Orca Research Trust said on Facebook.

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"As his heart slowed and his breathing became fainter he was comforted and supported by us all. His care team are deeply saddened by everyone's loss and respect their various ways of grieving."

The trust said a few hours after the orca's death, a karakia was performed followed by the Lord's Prayer in Maori.

"Kind and gentle words were spoken by respected members of the community. He was then gathered into the folds of the iwi and taken for a private ceremony to buried with respect and dignity on an island overlooking the ocean and where wild orca frequent."

The local community and the orca's care team scattered flowers, native leaves and sea shells in the calf's memory, the Facebook post said.

"We cannot begin to express our thanks for all the kind words, the support and the donations that all went into the team effort to care for him."

DOC ranger Steve Brightwell said the whole team was "pretty sad" the baby killer whale did not make it.

The orca had become like family to those closely involved with his rescue and rehabilitation, Mr Brightwell said.

The Orca Tactical Response Group said on Friday night the orca was making encouraging progress. He was given food and electrolytes and it appeared he was slowly gathering strength.

It was unknown what led to his decline in the early hours of Saturday.

Talking to the Bay of Plenty Times on Friday Dr Ingrid Visser, who was leading the operation, said being without his family was traumatic for the calf.

Minister of Conservation Maggie Barry expressed her sympathies to the many people who had worked exhaustively to try to save the whale.

Had the team been successful, the rescue and release of an orca that young would have been a world first.

"The chances of success were always slim - but those who gave their time and effort to the calf should be proud of their efforts.''