Shark expert calls on swimmers to be more careful after suspected attack

A shark expert is calling on beachgoers to be more cautious following a suspected shark attack at Waihī beach.

Nineteen-year-old Kaelah Marlow died on Thursday after reports she had been injured in the water. If confirmed as a shark attack, Marlow would be the first shark fatality nationally since 2013.

A post-mortem was carried out on Friday, but it is yet to be confirmed whether a shark was behind the attack.

Clinton Duffy, a marine scientist at the Department of Conservation, said many people had the mistaken perception that sharks were uncommon in New Zealand.

"There are actually quite a lot of sharks in New Zealand waters, and large sharks are reasonably common in-shore. They can even be very abundant in some places in-shore over the summer," he said.

Duffy said while attacks were uncommon - he counted just 14 fatal attacks since 1840 - people should always swim between the flags, and never alone at a non-patrolled beach. He said people should also avoid swimming at night, and where people are or have been fishing.

He said large concentrations of fish in the water or the presence of dolphins could also indicate the presence of sharks.

"For the most part, sharks are completely uninterested in humans, I've seen them myself swimming past people ... taking no interest at all," he said.

Surf Life Saving New Zealand said normal patrolling at Waihi Beach had restarted today, following the attack.

Regional manager Chaz Gibbons-Campbell said if anyone sees a shark, they should get out of the water and alert surf life savers.

He said there will be a flagged area for swimmers at Waihi Beach today.

Iwi have imposed a rāhui at the north end of Waihi beach, which remains in place, with the collection of seafood not permitted for a week.

Locals have also been gathering at the beach to place flowers in the water as a tribute to Marlow.