Below the surface: Dunedin's 'rogue shark' theory
New Zealand is in the top five in the world for shark attacks. How many were due to a single, deadly 'rogue' shark patrolling Dunedin's coastline?
It's a theory sounding more like the plot of the world's most famous shark movie.
A great white shark patrols the waters off a beachside community, where it soon develops a taste for human flesh.
Surely a work of fiction. Right? Well, maybe not.
* Below the Surface Chapter 1: Dunedin shark attacks killed three in 1960s
* Below the Surface Chapter 2: Dunedin shark attack claimed life of William
* Below the Surface Chapter 3: Dunedin shark attacks men spearfishing
* Below the Surface Chapter 4: Dunedin shark's 'Huge bloody eyes'
The rogue shark theory – basically that the same great white was behind all three Dunedin fatal attacks – was "widely dismissed", according to Clinton Duffy.
But after years of conducting photo identification and satellite tracking of great white sharks, the Department of Conservation marine scientist and shark expert believes there might just be something in it.
"It is not beyond the realms of possibility."
Just don't call it a 'rogue shark'. That's because Duffy prefers the description 'resident shark'; a shark which returns to an area such as Dunedin.
Most sharks were cold-blooded, so to survive and thrive in the colder waters off Dunedin would need to eat much more than sharks in the tropics.
INSPIRATION FOR JAWS
Duffy said the Dunedin great white encounters fitted into a category of hard-to-explain attacks, such as a spate seen in New Jersey, in the United States, in 1916.
Those four fatal attacks were believed to be the work of one shark, and were said to have inspired the fictional work of Jaws. However author Peter Benchley later played down any connection.
"The jury is still out on how many sharks were involved in that attack, much like the Dunedin one we still have no real idea how many different sharks were involved," Duffy said.
A spate of attacks over a short time frame "were very difficult to explain scientifically".
Adding weight to the rogue, or resident, shark theory was that there had been no more attacks off Dunedin since 1971, despite a known population of great white sharks and more people using the water.
DOES SIZE MATTER?
And then there is the estimated size of the shark from each Dunedin attack.
An analysis of witness statements and coroner reports, obtained by Stuff, show variation in the reported size.
And the attack on Barry Watkins in 1971 was by a shark estimated to be up to 4.8m in length.
Perhaps unconnected, but demonstrating the size of sharks in the area at the time, was a 1975 photo of a five-metre-shark captured in an Otago Harbour fishing net.
That whopping catch came out the same year as Steven Spielberg's movie Jaws warned cinema goers "You'll never go in the water again".
One person who knows as much about the Dunedin attacks as anyone else, lives halfway across the world in Ontario, Canada.
Steve Crawford, of the University of Guelph, is studying conservation and management of great white sharks in New Zealand.
His research included conducting more than 70 interviews with people from Otago to Fiordland.
"Some of those stories will blow your socks off."
His research included a world-first description of courtship and mating behaviour in great whites, occurring in Otago Harbour.
That research was expected to be released this month.
Crawford said he was struck by the "life altering nature of these single events".
"You had people whose whole lives were basically wrapped up in the water/land interface and when this happens they never went back."
He had no doubt the Dunedin attacks were the work of one shark.
"There is strong reason for suspecting in space and time that it was a single individual."
That was because the attacks were localised, and happened across several years.
His interviews revealed sharks often stayed in a particular area, in courtship and mating territories, such as the sandy areas near seal colonies off the Otago coast.
"You effectively have dinner and a movie."
OTAGO - PRIME SHARK TERRITORY
"The Otago Peninsula is prime white shark habitat, and not just for food, but also that mating territory."
"That's where the big male sharks and big females are getting it on."
The Dunedin examples were not the usual shark attacks of a predator ambushing prey from below, before taking a bite.
Instead those attacks showed elements of territoriality never seen before.
One of his interviewees, John Malcolm, was tasked with laying shark nets off city beaches, as "the whole city went nuts for a while".
Malcolm maintained he caught between 70 to 80 sharks in the nets over 11 years, along with dozens of dolphins.
Interestingly, the sharks were caught on the inside of the nets, with the largest great white measuring 5m.
He claimed his catch was under-reported by city officials, not wanting to alarm the public.
The nets were widely criticised, but Crawford said it was interesting they coincided with no more attacks.
"When you put these nets out and you catch big fish in the range of something that could have been involved in these attacks, and then all of sudden there are no more attacks, then it is not a smoking gun but shell casings on the ground."
But an old black and white photo from Port Chalmers in 1900 proved that "these large animals have been here on a regular basis".
The Otago Witness reported much excitement after a fisherman harpooned the shark, which had "been prowling about the harbour for some time past".
That excitement led a large crowd "desirous of seeing the shark" to crowd onto a landing stage which began to sink under their weight.
The shark was recorded as 5.5m, but that was believed to be an overestimate.
A SHOCKING DEATH
Just a few years later, and further up the coast in the picturesque seaside town of Moeraki, Dunedin engineer William Hutcheson, became the fourth recorded shark attack victim.
He was standing in chest-deep water, his son diving off his shoulders, when he was bitten and his calf "stripped from his knee to his ankle".
"Get ashore quickly," Hutcheson told his son. "I have been bitten."
A coroner's report of the 1907 incident said Hutcheson died on the beach within minutes, after "all the arteries in the leg had been severed".
The Press at the time warned "the bay is infested with sharks".
Hutcheson was one of 11 shark fatalities recorded in New Zealand, of which six were in the North Island.
The online encyclopaedia of New Zealand, Te Ara, claimed another fatality in Moeraki in 1967, but there are no other supporting records.
NZ FIFTH IN THE WORLD FOR SHARK ATTACKS
Meanwhile the International Shark Attack database, compiled by the Florida Museum, noted there had been 51 confirmed unprovoked shark attacks in New Zealand.
Of those 10 were recorded in Otago and five in Southland.
That places New Zealand fifth in the world for unprovoked shark attacks, behind United States, Australia, South Africa, and Brazil.
The largest confirmed record for a female great white shark – usually larger than their male counterparts – was just over 6m. Even larger sharks have been reported but questions remain over the accuracy of the measurements.
When the shark caught in Otago Harbour in 1975 was dissected the Otago Museum zoologist at the time, John Darby, conducted an autopsy on the specimen, finding in its stomach a skate and various molluscs and crabs.
The impressive jaws from that female remain on display at Otago Museum.
MONSTER OF THE DEEP
That display is next to the fossilised tooth of an extinct white shark, Carcharodon angustidens, which was larger and heavier than any living great white shark.
This prehistoric shark was related to another extinct megatoothed shark, Carcharocles megalodon, which lived approximately 23 to 26 million years ago. Recovered from North Otago limestone, the Carcharodon angustidens' teeth and vertebrae puts its size at potentially more than 9m long in length, and around eight 8 tonnes in mass.
Rumours of a monster shark lurking off the coast of Dunedin became almost urban legend over the last few decades.
A shark, nicknamed KZ7 after the America's Cup boat, was cited by several people during Crawford's research.
Inquiries by Stuff found one diver who had a close encounter with the shark in the late 1990s.
The woman, who declined to be named, said she was diving at Shag Point with two men, when one of her fellow divers gave a hand signal indicating the fin of a shark.
The massive shark circled around them four or five times as they nestled under a rocky ledge, about 20m from the surface. At one point the shark swam over her so close that she could have touched it.
"It totally knew we were there it was just checking us out."
She estimated the shark to be more than 5m long, as two of her lying lengthways could have easily fitted inside it.
"I was having images of my blood and guts everywhere."
Conscious of their air supply and the shark no longer visible, the trio swum to their boat, with each watching out at a different direction in case it returned.
"I remember getting to the surface and saying 'get me out of the water … there is a freaky big shark down there'."
The divers had post traumatic stress counselling after the incident, and despite a few jumpy moments with kelp had all since returned to the water.
"I put it down to an amazing experience."
SMALLER SHARKS MAY BE MORE AGGRESSIVE
Duffy confirmed he had heard of an extremely large great white shark – upwards of 6m – patrolling the Otago coast.
With some sharks able to reach up to 7m in length and live up to 70 years, the size of the animal was possible.
But whether it was linked to the fatal Dunedin shark attacks was another thing.
Shark Dive NZ operator Peter Scott, who is based out of Dunedin, has possibly seen more great white sharks in New Zealand than any other person.
He had heard about KZ7, the 6m long behemoth, but doubted it was connected to the earlier Dunedin attacks.
That was because larger sharks tended to be less aggressive than their younger male counterparts.
And those more aggressive ones had been dealt badly with by humans, he warned.
He believed the Dunedin attacks were the work of one, given there had been no more attacks since Watkins in March 1971.
"When you look at that whole history it probably was the work of one fish … it's been caught or died, and we have had nothing since."
CONFRONTING THE FEAR – SHARK DIVING
In an interesting twist, Scott took Watkins on a shark diving experience in 2018, watching three sharks up close.
"Once I got into the cage and the first shark came past, it was all excitement and just a tremendous thrill to be honest."
That was a different experience to the attack off St Clair, where he was in the water with a shark intent on feeding.
"Here I was inside a protected cage, and it was just a matter of taking in how wonderful these things are.
"It just impresses me how incredibly lucky I was to escape back then ... "
Watkins so loved his second, albeit safer, close encounter that he expressed his dismay over shark diving being ruled illegal by the Appeal Court in September 2018.
Scott was yet to decide whether he would challenge the decision in the Supreme Court.
He regularly saw sharks off Stewart Island, including those around 6m, but even 4m sharks "are majorly impressive".
While southern waters were known for large great whites, New Zealand – with its large coast line – had very few shark attacks, Duffy said
"Pick anywhere around the coast and you go long times without a shark attack."
But that's what makes the Dunedin cases – spread over a few years – so different.
FISH WASTE TO BLAME?
Duffy heard reports, which were also raised by Errol Hitt, brother of shark victim Graeme Hitt, that fish offal dumped off the Otago headlands may have contributed.
Discarded fish remains would have switched a shark from a resting mode into a feeding frenzy. The process, called 'chumming', was how fishermen attracted and caught sharks.
From Duffy's observation, a great white's hunting strategy with seals, was to inflict a fatal bite and it then waited for the animal to bleed out.
"They follow the blood trail and track the injured animal, and then come back when they think it is safe."
A 2009 study, published in the Journal of Zoology, found great white sharks behaved like serial killers when stalking their would-be victims.
That included stalking their intended target from at least 90m ensuring they would not be seen, and then attacking when light was low.
DUNEDIN – SHARK ATTACK CENTRAL
Dr Gavin Naylor, director of the shark research programme for the Florida Museum of Natural History, was aware of the Dunedin attacks, labelling the southern city as the "shark attack capital of New Zealand".
He believed the attacks were less about a rogue shark, and more about patterns of plankton attracting fish, then seals, then sharks.
Often those times coincided with the best surfing conditions. Surfers were in the water longer than swimmers so were more likely to be targeted, he said.
Naylor said those entering the water needed to "be aware you share the ocean with these creatures".
"Sharing the environment with these animals is the best strategy you can employ."
He stopped short of recommending shark repellent devices as "it gives people a false sense of security".
But there were things water users could do to minimise the chance of an encounter, said Naylor.
That included not going surfing at dusk or dawn, not wearing jewellery in the water, and not going swimming if you "see fish jumping out of the water".
"But someone could do everything you say and still get bitten."
You have been warned.
Below the Surface is a Stuff series about five shark attacks that occurred in the 1960s and early '70s off the coast of Dunedin. Three men were killed and two more seriously injured, devastating families, traumatising survivors, and sparking hysteria about the predator that lurked beneath. This is the fifth and final chapter.