Port River dolphin Marianna died after propeller strike

A post mortem on popular Port River dolphin Marianna has revealed a deadly injury caused by a boat propeller.

A Port River dolphin death was “most likely” caused by propeller strike, a necropsy has found.

Named after long-serving Whale and Dolphin Conservation volunteer Marianna Boorman, the 15-year-old male “Marianna” died in October.

The Environment and Water Department confirmed a post mortem of the dolphin “determined the animal most likely died from injuries sustained from a vessel’s propeller … (in) an unfortunate and tragic accident”.

“There was no evidence of wrongdoing or that excessive vessel speed was the cause, as commercial vessels are permitted in the Port River section of the Adelaide Dolphin Sanctuary under speed restrictions,” a spokesman said.

On behalf of the National Parks and Wildlife Service, the SA Museum found that the dolphin was in a good, robust state of health, with no signs of disease at the time of death.

Since the Adelaide Dolphin Sanctuary was established in 2005, three deceased dolphins have been found with injuries confirmed to be sustained by collisions with vessels. This is the first since speed limits in the Adelaide Dolphin Sanctuary were reviewed in 2019.

Supplied Editorial Fwd: Port River Dolphin Marianna

The Department spokesman said Park Rangers and Adelaide Dolphin Sanctuary volunteers regularly witnessed Marianna in the Port River surfing and jumping around the bow waves of large commercial vessels.

“This behaviour coupled with evidence collected during the post mortem leads to the conclusion that the dolphin most likely came into contact with a commercial vessel propeller during this play activity, resulting in sudden death,” he said.

But Ms Boorman challenged that suggestion, saying it was “unlikely”.

“Like many of the Port River dolphins, Marianna was very familiar with the the ships and tugs, he was a very experienced bow rider and would often surf and play in the waves they create,” she said.

“Speeding boats are an ongoing problem in the area. Only a few days ago numerous reports were made by members of the Public of a boat speeding up and down the inner port.”

Supplied Editorial Fwd: Port River Dolphin Marianna

Ms Boorman said it was “heartbreaking to hear” the dolphin’s death was caused by a boat strike, a direct result of human activity.

“Marianna spent nearly all his time in an area where the speed limit was 7 knots or less,” she said.

“To be killed by a boat indicates that either the boat was speeding and possibly changing direction erratically or there were other factors involved.

“It is clear that more needs to be done to protect and care for the Port River Dolphins and their environment.”

Volunteers at Whale and Dolphin Conservation have been asking for the necropsy report but have not yet received a copy.

The group is now calling for more policing out on the water to stop people speeding, harassing and approaching dolphins, as well as more resources and funding for both the Adelaide Dolphin Sanctuary and the SA Museum.

“Marianna’s death was avoidable and Marianna should still be alive,” Ms Boorman said.

“It is vital positive changes are made to protect the rest of the Port River Dolphins.”

Marianna Boorman has been volunteering with the Adelaide Dolphin Rescue since she was 13 back in 1995. She inherited her love of dolphins from her grandparents and is now passing it on to her children. Picture: Roy Vandervegt

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