Investigation launched into recent dolphin deaths in the Barker Inlet and Port River, following the death of bottlenose Hunter

The death of a fourth dolphin in as many months has been added to an official investigation amid claims the animal did not need to be euthanised. Warning: Video may cause distress.

Warning: This story features video footage of an animal in distress that some readers may find upsetting.

Preliminary results from the post mortem of the Port River dolphin ‘Hunter’ show he was in very poor health and unlikely to have lived much longer, according to the state government.

The University of Adelaide and SA Museum’s report is believed to back the advice National Parks and Wildlife Service rangers received from a veterinarian that Hunter’s condition was terminal.

On Friday morning the six-year-old male bottlenose dolphin was captured and euthanised.

Associate Professor in veterinary pathology, Dr Lucy Woolford, said the report showed six-year old Hunter had multiple infections that were likely connected to his recent and significant weight loss.

This included “a severe bacterial infection of the middle and inner left ear which had extended into the surrounding bones causing permanent damage to these structures” and “multiple skin abscesses”. His stomach was almost empty.

“The underlying cause of these infections will be investigated over the coming weeks, with extensive testing underway,” Dr Woolford said.

One of the Adelaide Dolphin Sanctuary’s former dolphins, named ‘Doc’. Image Credit: Selina Guckenbiehl

A spokesman for the Department for Environment and Water said Hunter had been losing weight and was reported to be behaving strangely in recent weeks.

“(He) was assessed by independent veterinary experts and subsequently euthanised on Friday morning due to ongoing deteriorating health,” the spokesman said.

Hunter was the fourth Port River dolphin to die in as many months but Jenni Wyrsta, of the Port River Dolphin Watch, said his death was unnecessary.

“There was absolutely no reason to put this animal down,” she said.

“Yes, he was unwell but he was fishing this morning, he was putting on weight, he was recovering.”

Ms Wyrsta witnessed the capture and lethal injection of Hunter and said the process was quick given that a previous dolphin, Doc, was left unwell for months.

“When we said he needs help, they'd say you've got to let nature take its course,” she said.

A young dolphin that was caught by the low tide in the Torrens river outlet at Henley Beach puts on a show for onlookers on October 8. Picture: Mark Brake

The August death of 12-year-old dolphin Tallula followed the disappearance of two male dolphins, Doc and Twinkle, in June and July. Both had fishing tackle injuries.

National Parks and Wildlife Service director of Conservation and Wildlife Lisien Loan said Hunter had been monitored for weeks.

“In recent weeks, the dolphin has been reported as appearing lethargic, emaciated and spending more time than usual on the surface,” Ms Loan said.

The dolphin’s body will be taken for testing.

Environment Minister David Speirs launched an investigation into dolphin deaths on August 21.