Riley Elliott with a Great White Shark on Discovery Channels's Shark Week TV series. Photo / Supplied
Despite recent warnings and a little apprehension among beachgoers, one man is excited about the promise of more sharks in the Bay of Plenty this summer.
Sightings of bronze whaler sharks at Mount Maunganui beaches last week prompted a warning for people to avoid swimming in areas where people were fishing.
Footage of a 2m shark cruising in the shallows at Ōhope Beach and clearing the busy holiday spot was also captured by a drone on December 27.
Auckland Museum curator of marine biology Clinton Duffy said bronze whalers were common and usually not aggressive but people should leave the water quickly and quietly if they spotted one.
However, PhD marine biologist Riley Elliott, affectionately nicknamed Shark Man, said his great white shark programme had struggled to gather research from around the Bay of Plenty since the floods of February 2023 and was hopeful La Niña would bring more sharks back to the region.
The Great White Project established a citizen-funded tagging programme during the summer of 2022/2023.
After two previous summers of continuous presence of juvenile great whites, Elliott tagged four of them, tracking their movements around north New Zealand waters.
“Ever since those floods, it seems like the little great whites all vanished.
“There were very few stingrays, bronze whalers, fish, I didn’t really see anything, let alone great whites.”
He said the floods were a “good reminder of the impact of sedimentation from huge rainfall runoff and the damage that does to the ecosystem”.
In recent weeks, Elliot said there had been signs of improvement.
He said big kahawai schools were back, and fish life was returning this summer.
“As the water warms up, it becomes a good nursery ground for everything from fish and crustaceans to sharks to come in and utilise those food sources.”
He said the last La Niña seemed to have caused great whites to populate the area in the first place, so he was very excited for the summer.
Elliott’s research shows about 100 million sharks a year are killed globally in fisheries. He said only 30% of the world’s sharks remained.
A report in the journal Nature indicated that worldwide shark numbers had declined by 70% over the past 50 years due to an 18-fold increase in fishing pressure.
Elliott has been tagging and tracking great whites since 2022, and in 2024 received an extension to his permit to continue his efforts at Stewart Island.
When the sharks mature, they migrate south to learn how to hunt seals.
“There was really nothing up in this northern region, but Stewart Island was incredible. One day we had 25 great whites around the boat, and they ranged from 6m adult females to 2m small juveniles.
“At the end of the summer, those big sharks will migrate, and the little ones will probably move further up the New Zealand coastline and stay in New Zealand waters.
“I have a feeling that when we start tagging sharks down there, we will start to see them between Stewart Island and the Bay of Plenty area, which is being occupied by young juvenile great whites. However, La Niña being a possible driver, being absent this year may mean fewer sightings of them in northeast New Zealand.”
Elliott’s app, The Great White App, has become a significant part of his research.
“I think people learned a lot from the Great White App.
“Daisy, the famous one that was in between the Waihī flags right on the first day of the school holidays ... People didn’t run and panic.
“They continued with their lives because they were empowered by knowledge that this is a small great white that eats stingrays and crabs and small fish and is actually very vulnerable and cautious and scared.”
Elliott said citizen science was priceless and if you came across a shark it was vital to get a photo or video if it was safe to do so and send it to him.
Elliott said the tags were all sponsored by members of the public within a couple of weeks of being announced.
“We deployed four of those and we luckily got those four back. They revealed some amazing tracks.”
“The most special was probably Mananui - the big 3.2m one which had been sighted three years in a row from fishery pictures.”
Elliott said it showed the animal was returning to that site. After the floods, she left and went up around the North Cape and around 90 Mile Beach. Then she returned to the harbour and dropped her tag.
The shark tags were meant to be deployed and then dropped after a period of time as a more humane way of gathering data from sharks.
“I really hope that the damage from the floods has recovered and that we may see the sharks again this coming summer.
“I got the tags, refurbished them with new batteries and so they’re all good to go.”
There were 20 tags in total so there were still 16 to be deployed.
Elliott said the key finding from his research was the discovery these sharks were very vulnerable to environmental change.
“Most fish species through the winters go offshore into deeper water where it is more thermally stable.
“The larger sharks migrate to Polynesia and northeast Australia during our winter.”
He explained they come to New Zealand to hunt seal pups, which leave the island through the summer once they have weaned off their mums, “That is the easy pickings that the great whites are after.
“Come to the end of summer, those seal pups have all left. The great whites then go to tropical waters where it costs less energy to stay warm.
“When it’s warm enough to swim is generally when the sharks are in town.
Elliott said it was part of the lifeguard’s duty to look out for sharks. “They have policies that they’ll get you out of the water for 15 minutes to let the shark pass on through and get on with its day.
“It’s not because there’s an innate danger in that animal being there, but it’s a respectful thing to do.
“Being respectful of the environment of the animals in it and where you do your activities is best practice.”
Sharks were most active at night, when visibility was low, so Elliott recommended not swimming at this time.
“Dusk and dawn is the cliché, the crossover between day and night and that can be reduced visibility, but more importantly, it is when all of the ocean is hunting each other.”
However, as a surfer, Elliott said the best time to surf was at night and said you must understand what environment you are going into and you accept the risks that come with that.
“Do not surf where people are fishing. Do not surf where there is a whole bunch of fish life or workups. Do not surf at a dirty river mouth where visibility is poor and effluent may be going out, those factors diminish the shark’s ability to determine that you’re a person and you’re not on the menu.”
If you go fishing, don’t fish at the nearest bay where people go swimming as then you will be overlapping sharks’ food and generally murky water where people are jumping in.
“That is a recipe for mistakes to be made.
“Sharks don’t eat people; they sometimes make mistakes and think that you are their natural prey.
“We have gone into their supermarket that they have shopped in for millions of years and if it is too sharky, you should move to another spot.”
Elliott said to keep your eyes out for sharks and share photos that you capture of them.
“If you happen to accidentally hook a shark, treat it kindly, bring it alongside the boat and cut the line right beside the hook and let it go.
“If you catch a great white, make sure you report it to DoC because that’s a legal obligation.”
If you see a great white and it is safe to do so, take a photo or video and send it to Elliott at nzsharkman@gmail.com.
Report details of sightings, captures or strandings to DoC sharks@doc.govt.nz or to 0800 DOC HOT (0800 362 468).
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