Terry, the aquarium’s oldest resident, arrived in Napier from his birthplace in Fiji in the late 1970s.
He died on September 11 at the aquarium after nearly 50 years in captivity.
An expert says internal bleeding, without there being extenuating circumstances to cause it, is possible in older turtles.
Mark Feldman, who has researched the reproductive physiology of turtles for more than four decades, said in the wild, bleeding deaths in turtles were almost always the result of trauma from shark attacks, boat strikes or fish hooks.
Feldman, who is based in the US, said if gross bleeding was detected in an autopsy, the cause would be “obvious” to the vet.
He said the two most likely causes of internal bleeding deaths for an aquarium-bound turtle like Terry were cancer or plastics that they had ingested while in the wild.
Feldman said turtles of a certain age could also suffer internal bleeding as a secondary reaction to a wide variety of other age-related diseases, just as in humans.
“At 50-plus years, this turtle was already old, and some cancers are common in these animals,” he said.
“Ingested plastics can gradually erode a hole in the digestive tract. Many plastics are not detectable on x-rays.
“The turtle may have ingested them before coming to New Zealand.”
Terry arrived in Napier as a juvenile, about the size of a dinner plate, after being relocated from a closing aquarium. He grew to 90cm long, weighing close to 80kg.
At the time of his death, National Aquarium general manager Joe Woolcott said Terry was popular with visitors and beloved by staff, including former employees through the decades.
“We are deeply saddened by Terry’s passing,” Woolcott said.
“Those who worked closely with him cared for him every day and developed a special bond over many years.
“His loss is being felt profoundly and we are taking time to support one another as we mourn a truly special and much-loved animal.
“The aquarium team were dedicated to his wellbeing, care and enrichment and he was a much-loved member of the aquarium whānau.
“He will be missed by many who loved him, staff, visitors and the wider community.”
Over the years, tourists and locals raised concerns with aquarium staff about the size of Terry’s tank and his solitary existence.
He was housed in a 90,000-litre heated salt-water tank to emulate tropical Pacific conditions. By contrast, the National Aquarium’s oceanarium water temperature matches that of Hawke Bay.
LDR is local body journalism co-funded by RNZ and NZ On Air.