A 2.8-metre great white shark hauled out of the entrance to Wellington Harbour had been feeding on large marine mammals.
A team at Te Papa defrosted the shark, caught last year, for measuring this week.
It was the largest great white specimen preserved intact in New Zealand, Te Papa collection manager Andrew Stewart said.
One of the biggest surprises, for the examiners, was discovering that the shark had an empty stomach except for a seal claw and some tape worms.
The claw was the "smoking gun" that it had started eating seals, he said. "This shark had moved from being a fish eater to being an apex predator ... These are animals that sit right at the top of the food pyramid."
As great whites grew they needed more energy, which they got from high-blubber marine mammals such as seals.
"They are high-octane engines that require a lot of feeding."
Mr Stewart said having a large intact specimen would be useful for scientific research.
Already, more than 100 measurements had been taken from it.
Scientists would study markings to establish if the shark had been spotted off Stewart Island, where Conservation Department shark expert Clinton Duffy had collected photographic records of great whites.
Cells of the shark would be analysed to try to discover what else it had been eating.
"It should open the door for the understanding of this elusive predator," Mr Stewart said.
Although great whites were aggressive predators, they did not pose a significant risk to humans, he said. `They are not patrolling up and down the beaches trying to kill us."
The shark was hauled from the water near Barrett Reef in October last year by Peter Amitrano and Alfonso Basile, who had set moki nets.
Great whites are a protected species, meaning if they are caught, the Conservation Department has to be notified.
Department marine mammal specialist Laura Boren said there was anecdotal evidence that seal numbers on the south coast of Wellington were increasing.
There were also more pup and yearling seals, which great whites tended to catch because they were not as good at escaping.
- The Dominion Post
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