A fisherman has described the moment he pulled a bag of human remains out of Auckland's Gulf Harbour on Tuesday.

Paul Middleton said he was in the Whangaparaoa area to do some fishing, trying to catch some some decent-sized kahawai or snapper.

He had gone to Army Bay this morning, but had not found much fish so he came back around the ferry terminal.

"I [threw] my lure out ... and nothing much was happening but there was a bag out there."

▶ Watch the interview with Paul Middleton here (warning - contains some graphic details):

He said at the time he did not know it was a bag, and thought it was a log or a dead animal. Boat had been passing through the area, near the entrance to the marina.

"Anyway the wind changed, brought it in to the coast. I think yeah, anything floating in the water brings fish around, so I'm targeting it. I got that perfect shot, like millimetres to the side of it."

He hooked it and pulled it into the shore - it was heavy but easy to move - and managed to pull it up the rocks a little.

"Took the hook out and thought 'Right, let's see if it's a bag of rubbish and I need to dump it in a rubbish bin or something'."

Paul Middleton hands over his fishing rod. Photo: RNZ / Nick Monro

He struggled through "layer and layer" of plastic to open the bag.

There was "a bit of clothing ... and then there was this hand sticking out".

It was at that point that he called police.

"Two cops turned up and they thought I'd actually said there's just a hand in a bag and then they went down there and went, 'Oh no we've got a body'," Middleton said.

The hearse carrying the human remains found near the Gulf Harbour ferry terminal. Photo: RNZ / Nick Monro

Middleton said he did not try to open the bag further once he discovered the hand.

Police earlier confirmed that a body had been found in the water near Laurie Southwick Parade on Tuesday afternoon.

They were treating the death as unexplained and the area was cordoned off while officers made enquiries in the nearby area, they said.

There was no immediate risk to the public in relation to this death, said police.

Police at Gulf Harbour. Photo: RNZ / Nick Monro

This story was originally published by RNZ