“The point is it’s engaging and it’s important to them [sharks] and us, but they are pretty vulnerable,” he said.
“Every kilometre they move, they are running a gauntlet of potential death.”
Elliot was speaking of the risk recreational and commercial fishing posed - with long lines and set nets often trapping and killing the sharks.
“A recent Niwa report shows 53 great white sharks were caught and killed in commercial fishing [over the past decade] - and that’s just what’s reported,” he said.
One great white, named Mananui, was tracked travelling from Bay of Plenty, around North Cape, to 90 Mile Beach and back - a roughly 1130km coastal trip.
Another, the now-famous Daisy, disappeared for a month, evading tracking when she swam into deeper waters.
Elliot said he believed their movements reflected changing locations of their food sources and the suitability of areas for hunting.
“These sharks are a lot smarter than we give them credit for. Great white sharks are visual predators - they prefer to be in water where they can see their prey [food].
“I feel, after the flooding on January 27 and [Cyclone] Gabrielle, floodwaters pushed normal fish life offshore or further north,” Elliott said.
“They [the sharks] escaped the murky [flood] water. The point is: They have to feed, and if they can’t find food they’re going to go elsewhere to survive.”
Elliott said it was “all new learning, new data and it’s hypothetical”.
“But when you see these tracks what’s amazing is the sharks are aggregating [concentrating] in areas characteristic of nursery ground habitats - sheltered waters and bays where you’ve got a large source of prey.”
Regarding Daisy’s disappearance, Elliott said it revealed sharks do not need to surface regularly. The tracking relies on the great whites being close to the surface.
“These aren’t dolphins - they don’t need air - we find they surface a lot when they’re migrating, travelling, or feeding. [They eat] kahawai at the surface, whereas stingrays or school sharks [great white prey] are bottom-dwelling.
“I’m trying to quantify where the critical habitat areas for the survival of the species are. That is always the nursery ground because that’s where the next generation is.
“Threaten the babies and parents and you threaten the future,” he said.
The health of great whites and their population size was an indication of the status of the wider ecosystem, including the fish they eat and how they were impacted, Elliott said.
“They’re a keystone species - remove it and it has a disproportionate effect on the wider ecosystem - the sighting of great whites means a healthy and intact ecosystem.
“Around the globe, great white populations, most famously in Africa, are disappearing. It was rumoured orcas had something to do with it. But really it has something to do with a decline in their food source - school sharks being overfished.”
Elliott received a Department of Conservation permit in June last year to track and satellite-tag 20 great whites, allowing people to see where the animals are travelling live on an app.
The project is driven by funding and support from the public and is hosted by the Sustainable Ocean Society - a non-profit established by Elliot and a group of his friends.
Elliott tagged Daisy on December 3 inside Bowentown’s harbour - just north of Tauranga and close to the area off Bowentown beach where teenager Kaelah Marlow died after being bitten by a great white shark in 2021.
