The killer whale, less than eight feet (2.5 meters) long and believed to be between four and six months old, made headlines when it washed ashore near the capital Wellington after from parting with his pack almost two weeks ago.
He was not weaned and hundreds of people volunteered to help with 24-hour care, as he could not survive alone in the ocean.
Conservationists, who called the killer whale Toa (Maori for “warrior”) housed it in a makeshift pen in the coastal suburb of Plimmerton, where it was fed a special teat every four hours while an air and sea search was conducted to find his mother. .
Whale Rescue, an organization that had been helping to care for Toa, posted on social media that his condition rapidly deteriorated Friday night.
“Veterinarians there rushed to help him, but could not save him,” the statement said.
Conservation Department Marine Species Manager Ian Angus said they were aware that the longer Toa spent in captivity and away from his mother, the more likely his health would deteriorate.
“Toa passed quickly, surrounded by love with his last days as comfortable as possible,” Angus said.
“Throughout this incredible endeavor, we have all been united in a desire to do what is best for Toa. Finding him and reuniting him with his pack remained our goal as we headed into the weekend.
“This calf had captured hearts, and no one wanted to believe that he had no chance to fight.”
Despite being known as killer whales, orcas are actually the largest species of dolphin, with males growing up to thirty feet.
Recognizable by their distinctive black and white markings, they are listed as critically endangered in New Zealand, where their population is estimated at 150-200.
Killer whale pods are relatively common in Wellington Harbor, where they have been observed hunting stingrays.