This was one of Newshub's top stories of 2023. It was originally published on September 26.
Tauranga Harbour has become a pupping ground for great white sharks in New Zealand and a shark expert is warning Kiwis of an increase in shark encounters in the water this summer.
As hot, dry months and holiday season creep closer, marine biologist Riley Elliott is asking Kiwis to keep an eye out for sharks when swimming.
It comes as Daisy the great white remains untraceable since her tracking tag was lost.
Elliott uses satellite tracking tags to pin the location of three great white sharks, Mananui, Daisy and Swaj (Jaws spelt backwards), as part of a research project that aims to answer three questions - where did the sharks come from, why are they here, and how do their movements overlap with people?
Through his research he's found that the sharks, located in the North Island, "identify with the Tauranga harbour as a definite nursery and pupping ground".
He's seen reports of "booming fish life" in areas such as the harbour, which he believes produce ideal nursery grounds for the species, "and this we have seen pupping in such regions increase".
Elliott said the drivers of the growing population are "fluid and "hard to pin down".
However, he said they are "likely a combination of improved habitat" resulting in a "population growth of the species".
Elliott believes it could also potentially be "just one mother great white shark who has pupped in the harbour and continues to".
He said research has shown the Tauranga Harbour has continued to be the number one spot for the species.
"Almost all sharks tagged resided for long periods of time within the region, reflecting it as a preferred habitat," he said.
"We saw and tagged newborn great whites like Swaj in the harbour indicating it is a pupping ground.
"Over a dozen individual great whites were identified in the Tauranga Harbour region in just six weeks.
"It reflects the fact that these sharks value the very healthy ecosystem of Tauranga Harbour, and thus we will likely see previously tagged sharks again, so we can re-tag them, and tag new sharks yet to be seen.
Hotter weather means more encounters
Elliott researches the increase in great white sharks and believes with the hot weather, more people will be entering the water - leading to an increase in shark encounters.
"Hotter weather means more people, more often, will be going into the sharks' environment," Elliott explained.
"With more bodies in the water or more eyes on the water, there's simply an increased probability of people seeing sharks."
Elliott said despite there being warmer waters it does not equate to more sharks coming closer to shore.
He said the change of environments for any habitat can redistribute species, however, the main reason for increased shark encounters is that "we go into the sea which they live in".
Untraceable great white shark
Elliot is also warning swimmers to be cautious as one of the three tagged sharks, Daisy, remains untraceable after her tracking tag fell off and washed up on a Tauranga beach earlier this year.
Daisy was last sighted on December 3, 2022 and Elliot urges people to keep an eye out for her, as she will likely be hanging around the Tauranga Harbour.
Daisy's tag was found in June by a man who was walking his dog on a beach in the suburb of Gate Pā, in the Bay of Plenty and ended up back in the hands of Elliott.
Elliott said, with the tag back, he's hoping he can find Daisy and "continue to learn about her".
"I have cleaned the tag up and will be able to re-deploy it on Daisy again this coming summer if we see her again, which we can determine by the unique markings on the dorsal fin and pigmentation patterns on their gills," he said.
Advice for people who encounter a shark
Elliott stresses that people must keep an eye out for sharks when they are in the water.
"If you see one while in the water, try to remain calm. Most of these small great whites eat small fish and rays," he said.
"Calmy exit the water and inform other water users in the area… it is the sharks' home at the end of the day, we just play in it."
And Elliott has a reminder for people who plan on fishing this summer.
"If you are fishing, pull your lines in as you don't want to hook them, as it could endanger their lives, your own, and it's illegal," he reiterated.
Elliot urges anyone who captures footage of the sharks to send it to nzsharkman@gmail.com to help with his study.
"I am only one boat and one set of eyes, but with millions of us on the water, your observations are super powerful data for us to better understand where these amazing creatures inhabit."
