Call for more care
Injuries which led to the death of a common dolphin at Torbay highlight a need for care by boat and jetski users.
The call for vigilance comes from marine biologist Dr Karen Stockin after the dolphin's death from an injury she says was likely to have been caused by a collision in the Hauraki Gulf.
Dr Stockin is a lecturer at Massey University's Institute of Natural Sciences at Albany. She carried out a post-mortem this week after being called to Toroa Point, Torbay, on Sunday, where a 1.7-metre dolphin was seen floundering in the shallows.
"The animal had a notable impact injury to its lower left side," she says.
"The adolescent male common dolphin died soon after we arrived.
"This dolphin was likely paralysed in its lower body as a result of the significant blunt force trauma it had experienced.
A section of its lower spine was completely shattered and extensive internal trauma was evident."
People at the beach reported the injured animal to the Conservation Department.
The dolphin was earlier seen swimming off the bay with other dolphins where small motorboats and jetskis were also operating.
Dr Stockin has been researching the New Zealand common dolphin in the Hauraki Gulf for the past decade.
She says they forage and breed in the gulf and are generally able to avoid boats that follow a predictable course.
However, small speedboats and jetskis that change speed and direction erratically create a hazard for marine mammals, she says.
Brydes whales expert Dr Rochelle Constantine of the Auckland University School of Biological Sciences agrees.
Around 50 of these larger whales live permanently in the Hauraki Gulf and are also at risk, she says.
While it is larger boats and ships that cause fatalities among this group, smaller boats can still cause injuries, she says.
Some whales have been seen with "zipper" marks on their backs from propeller blades.
The Marine Mammal Protection Act requires boaties to keep at least 50 metres from marine mammals at speeds of no more than 5 knots. That places the onus on operators to be vigilant, Conservation Department spokesman Phil Brown says.
North Harbour News