A rare hourglass dolphin examined by Massey University scientists is believed to be only the second in 150 years to strand on the New Zealand coast.

The 1.7m, 78kg male was found dead at Flea Bay, near Akaroa, on September 5 and underwent a post-mortem on Friday at Massey's Coastal-Marine Pathology Unit at Albany. It is one of only a handful of hourglass dolphin carcasses to ever be examined.

Department of Conservation staff first thought it was a dusky dolphin but when it arrived at Massey's unit on Thursday, marine ecology lecturer Dr Karen Stockin, who headed the post-mortem, was shocked to discover it was an hourglass - a species rarely seen in New Zealand waters.

"Having access to this carcass is incredibly exciting for us as so little is known about these animals, their diet and biology," Dr Stockin said.

"This is a once-in-a-lifetime opportunity for us to collect detailed data and to add significantly to the scant knowledge of this species."

Researchers will collect baseline biological data via a thorough examination of all organs, from teeth to tail stock. Tissue samples will be sent to Massey's veterinary pathology laboratory for further testing, while it is hoped the preserved organs can be held at Te Papa for future studies.

Post-mortem findings and a CT scan will be written up for publication.

Hourglass dolphins, also known as skunk dolphin, wilson's dolphin and southern white-sided dolphin, are distinguished by their white "hourglass" marking along the length of their black bodies.

They are polar, usually found in Antarctic waters, and marine mammals collections manager at Te Papa Museum Anton van Helden said they rarely travelled out of the Southern Ocean.

- NZPA