"That'd be a kahawai," Jaan Robertson's uncle declared as line started spilling off the reel in Auckland's Waitemata Harbour.

When a 4m great white shark leaped out of the water they realised they faced more of a challenge.

The four family members were fishing for snapper 100m off the Te Atatu Peninsula in only 2.5m of murky water on Monday afternoon. They'd caught a couple of fish and were getting ready to head back to shore when Jaan's brother, Mat Robertson, felt something strike his whole-pilchard bait.



"He said, 'Phew I've got something on here', and my uncle goes, 'That'd be a kahawai'," Jaan told the Herald on Sunday.

The rod had started straining as the heavy line screamed off the reel.

"S***, I can't hold this," Mat said, handing the rod to his more experienced brother. That's when the shark jumped. "I thought it was a freakin' whale at first, it was so big," said Jaan. "I just started screaming at the guys, 'Get the anchor up, quick, quick, quick.' And when it jumped there was this big slap like a whale. But you could definitely see it was a shark by its underbelly - it was really white and you could see the teeth in its mouth."

It is one of several sightings of what experts believe could be the same great white around Auckland in recent days.

The foursome managed to haul anchor and back the boat towards the shark. Jaan even managed to get a bit of line back from it.

"I don't want to kill an animal like that or hurt it, so if I can get it closer to the boat and cut the line off at its mouth it's going to have a better chance of surviving," he said. "But then it did another jump and the line broke. I think it landed on the line."

They initially thought it was a mako but the Department of Conservation told them that, based on their description, it was more likely to have been a great white.

"It wasn't scary. It was amazing and exhilarating. It was like watching a car jump out of the water."

DoC shark expert Clinton Duffy said the shark would have weighed more than 800kg. He was aware of 22 shark sightings in the Hauraki Gulf since 2000 - seven confirmed, six reliable and nine unconfirmed.

Great whites can weigh more than 2.5 tonnes and travel up to 100km in 24 hours. Photo / Thinkstock

The largest confirmed sighting was a 5.5m giant spotted 10 nautical miles north of Gannet Rock on Waiheke Island in 2003. Duffy said the latest sightings were likely great whites, not makos, which were rarely seen in the harbour.

On December 18 at Okakari Pt, near Leigh, a family spotted a shark "as big as a tractor" breaching.

And Te Atatu man Mike Fleming also had a close encounter with a 4m giant just off Kauri Pt on Friday.

He, his son and son-in-law were in their 5.5m vessel in about 15m of water when they had heard a huge splash behind them. "At that point I thought it was perhaps a kingfish or stingray but while we were looking over to that side of the boat, probably no more than 7m away, this shark came about halfway out of the water.

"He was huge. He was big. It was enough for all of us to go into mass hysteria on the boat."

They had decided to pull anchor and put distance between them and the shark.

"It's not a big boat but it's substantial enough to feel safe on. This would be one of the few times I felt a little unsafe - we felt a little insignificant, to be honest. If he had hit the boat he would have created some damage."

About half an hour later they saw the shark breach again. "It was extremely unnerving because of the sound of him going back into the water. I mean, it was actually quite freaky. It was like someone dropping a car into the water," he said.

Duffy said there was a good chance it was the same shark Jaan and his crew had seen.

Great white sharks could weigh more than 2.5 tonnes and travel up to 100km in 24 hours.