Auckland boaties have mounting concerns over sharing a marina with a boat-popping leopard seal, after footage emerged of it turning another seal into mince meat.

One boatie, Simon Hull, said it was only a matter of time before the leopard seal turned her sights on a child or pet.

He wanted her gone – but that's simply not an option according to the Department of Conservation.

Abigail Dougherty / Stuff Owha the leopard seal is typically spotted sunbathing at marinas and boating clubs in Auckland.

The 300kg apex predator, called Owha by locals, has been lolling around in marinas around Auckland's Waitematā Harbour since 2015.

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She is known for her highly inquisitive behaviour and penchant for destroying fenders and popping inflatable dinghies.

Westhaven Marina staff estimated she had ruined about 50 pieces of equipment over the years in their marina alone, causing thousands of dollars worth of damage.

Identifiable by the two parallel scars on her back, she was filmed killing and eating a fur seal at the same marina in November.

Hull, who is a berth holder at the marina, said the seal had caused "thousands of dollars of damage" to his property.

Supplied Westhaven Marina said Owha enjoys popping inflatable dinghies and destroying fenders.

"She's popped one of our inflatables and ripped about $2000 worth of fenders up that are now unusable."

He has heard reports of it chasing dogs, showing her teeth to divers and popping inflatables while people were in them.

"Apart from the thousands of dollars of damage its done, clearly the animal is lost and I contend that DOC should do its job and relocate the animal back to its natural habitat.

MARK LEONARD Auckland boaties have concerns about Westhaven Marina's resident leopard seal after seeing it tear apart a fur seal.

"I believe it's just a matter of time before it grabs a dog or a child. It needs to be either relocated or euthanised."

Relocation not an option

Methods of relocating the mammal have been explored and deemed too risky.

Supplied She can often be spotted lazing around on pontoons.

Niwa marine biologist Krista Hupman said it would be unsafe to both potential captors and the leopard seal.

She said because of her immense strength and size - about 3 metres long - she couldn't be captured in a net and it would be unsafe to even try.

"We would have to tranquillise an animal like a leopard seal to be able to relocate it.

"But because of the unknown body weight there is a very high chance that that would kill her."

Even if authorities did undertake what would be a costly relocation exercise to the Antarctic, Hupman said there would be no guarantee the seal wouldn't make her way back to "where she wants to be".

"She knows New Zealand like the back of her hand; she started off in Otago, she moved up to Bay of Plenty and then Auckland and now goes between Auckland and Whangarei."

DOC echoed this position.

"Anaesthetising seals will almost certainly result in death due to their 'dive reflex'," said Auckland operations manager Kirsty Prior.

"It is also very likely that the seal, if not killed, will find its way back relatively quickly. The cost of the exercise and likelihood to fail are not a good use of tax payers' money."

Leopard seals are protected under the Marine Mammals Protection Act 1978, and it is an offence to disturb, harass, harm, injure or kill a seal.

All about Owha

In 2016 Māori hapu, Ngati Whatua ki Orakei, named her "He owha nā ōku tūpuna", or Owha for short, meaning treasured gift from our ancestors.

She has been visiting Auckland Harbour since 2015 and usually spends several months in Auckland waters before moving on, often further north to Whangarei.

Hupman said Owha was probably the most curious leopard seal recorded in the world.

"She's always been extremely curious, we should definitely give her the space and respect she requires.

"She's definitely seaking out some form of enrichment and fenders and boats have been her thing for the last two years but there are ways we can manage that without going to drastic measures like killing her."

She said she's been relatively well behaved for an apex predator.

"If anything, I think for an apex predator ... to have no recorded incidents of aggression towards humans is pretty incredible."