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A fisherman faced a terrifying 10-minute walk back to shore after being savaged by a shark while setting his net.

Ken Lindberg spent five days in hospital after suffering serious injuries while fishing with a friend off Maraetai.

"We were just checking the net, just walking along lifting the top up a bit," he told Newstalk ZB.

"The next thing I felt this almighty clamp go around my leg. I said to Jeremy, 'We're out of here'."

Lindberg said his left leg started to tighten up as the pair waded back through the surf but was only able to look when they reached shallow water.

"All I could see was this almighty gash and a lot of blood pouring out. I thought, 'All I want to do is get back to shore'."

He made it back to his friend's house where a towel was wrapped around the wounds to stop the flow of blood.

His friend's wife then took him to Beachlands Medical Centre.

"The doctor had a look and said, 'It's an ambulance for you'."

Lindberg was pushed out in a wheelchair with his leg still bleeding and taken to hospital.

He needed 10 stitches above his ankle, four stitches to close his severed Achilles tendon and will not regain any feeling around his little toe.

"I haven't been out setting the net since then," Lindberg said.

Department of Conservation shark expert Clinton Duffy said if Lindberg's wounds were the work of a shark it was probably a bronze whaler.

The species can reach up to 3m in length and are common in New Zealand waters around summer.

While they don't usually attack humans, it could have been attracted to Lindberg's fishing spot if there were distressed fish in the net. "That would be enough to attract a shark into the area looking for a feed."

Duffy described such shark attacks as "slash and run attacks" that usually target a person's hands and legs.

"Shark attacks are always a case of bad luck and generally being in the wrong place at the wrong time."

Duffy said it was possible Lindberg's wounds were the work of a stingray, which, like sharks, sunbathe in shallow water in summer.

A stingray disturbed by a fisherman could easily lash out with its barb, he said.

"They're basically barbed knives strapped on to a lump of muscle."

Volunteer ambulance officer Calvin Hicks has lived in Maraetai for 12 years but never treated a swimmer or fisherman for a shark bite.

However, he is used to seeing bronze whalers and, on one occasion, a great white off the coast of Waiheke.

"You've got to have respect for the ocean, there are things out there that are going to eat you and you're on their turf."