World first research into great white shark behaviour in South Island waters is bringing fascinating new insight to the surface.
Kathryn Ryan talks to Steve Crawford from the University of Guelph in Canada who is studying their conservation and management.
Thanks to his research there is now greater understanding about their individual personalities, courtship and mating behaviour, plus a hypothesis that great whites may be acutely aware of, and responsive to, the female human scent.
Photo: https://www.whitepointer.cloud/
Crawford spent six months in New Zealand investigating Māori, local and science-based knowledge.
Historical records told him the south end of the South Island had the greater number of human to great white shark interactions and this is where he based most of his research.
Crawford interviewed as many experts from as many different backgrounds as was possible.
He interviewed two cage dive operators, Mike and Pete, for around 10 hours each – far longer than any of the other participants.
“Their exposure to the white sharks was so incredibly profound, they were seeing animals within season on repeated cases, such that they began to know their individual personalities, they gave them names, they could recognise the animals within season over time, but they also saw the animals over years.”
White pointers are not typically full-time residents of the South Island, Crawford says.
Their history in the region began with small males showing up and gradually they grew larger, before the large female sharks came around.
“That, to an ecologist, is a very clear sign that something is happening that is gender-specific. That is to say, quite possibly that is related to the reproduction of the animals. That there is a staging in behavioural complexity that then can lead to the courtship and mating of these white pointers.”
Crawford says scientists have never observed this before.
Great white sharks are extremely wary and stealthy, he says. The only thing that compromises this is their incredible curiosity.
“If anything is happening on the surface, it’s almost if they can’t help themselves, they have to come and check it out.
“There are examples of photographs dating back to the 1830s, 1820s of large, massive white pointers that were being caught in Otago Harbour and in the waters around the Otago peninsula.”
There was clearly something attracting them to the region, he says.
“And the simplest, most straight-forward explanation is that there’s an abundance of food in that region, both in terms of the marine mammals but also, not too far off shore you’ve got extremely productive fisheries.”
It turns out, the animals need to engage with each other, court each other and mate in secret, he says.
“White pointers are extremely sophisticated with regards to their reproduction; a lot of people think that because sharks have extremely long lineages that they are evolutionary primitive, but it couldn’t be further from the truth.
“The first thing to consider is in this species of shark, it’s internal fertilisation, which means the male and the female have got to be in close proximity so that the male using the claspers can internally fertilise the female.
“Secondly, the embryos are developing within the female and she has a variety of advance techniques to get them up to full size before she gives birth.”
People don’t realise that pregnant white pointers express a uterine milk that the embryos drink in the uterus and in some cases, she passes down unfertilised eggs for them to feed on, he says.
“By the time those pups are born, they are fully able to take care of themselves, they are extremely well-designed predators.”
Shark attacks
Crawford says shark attacks are extremely rare in New Zealand coastal waters.
In Australia, it’s a completely different story.
However, in 1964, ‘66 and ‘67 there were shark attacks on the Otago Peninsula that had profound social and psychological implications, he says.
People Crawford interviewed, who remembered the attacks at the time, told him that all you need is one bad apple.
“If you had one white pointer that was perhaps sick, or you had in other circumstances we know…especially the two most recent attacks in New Zealand waters, they were juvenile sharks, they were taking a bite at something, they were curious, they thought, hey this might work out.”
The three deaths in the 60s suggest there was one single animal that was the culprit, he says.
