Researchers say these sharks are an iconic species that are important food resources, tourism attractions, and top predators on coral reefs.
They are attributing the decline to the overfishing of sharks and their prey through destructive fishing practices, such as the use of longlines and gillnets.
Illegal fishing of sharks for their fins was also causing catastrophic declines of shark populations worldwide.
Dr Adam Smith, a senior lecturer at Massey University's School of Natural and Computational Sciences, provided data on sharks in the Kermadec Islands, New Caledonia, Fiji and Tonga.
He first heard about the project in 2017 and was impressed by the sheer scale of what it was aiming to achieve.
The university had just purchased some bait cameras for a separate project, so he got in touch with Global FinPrint to see if they were interested in collaborating and accessing their findings.
"I was intrigued and wanted to become involved because sharks are rare and very hard to study," Smith said.
"Contrary to popular belief, they are usually very shy, so sometimes we see lots of sharks on the videos but when we go scuba diving in the same places, we don't see any."
Coral reefs are found in some of the remotest places in the world and most of them are very hard to get to.
"It was such a privilege for me and my colleagues and students to see first-hand some of the most remote and pristine coral reefs in the world," Smith said.
"It was a rare glimpse of what marine ecosystems would have been like before humans began to exploit them."
The study, also involving Niwa fisheries scientist Dr Jade Maggs, revealed several countries where shark conservation is working and the specific actions that can work.
The best performing nations compared to the average of their region included Australia, the Bahamas, the Federated States of Micronesia, French Polynesia, the Maldives, and the United States.
The study showed these nations reflect key attributes that were found to be associated with higher populations of sharks: being generally well-governed, and either banning all shark fishing or having strong, science-based management limiting how many sharks can be caught.
Smith said sharks were more vulnerable to overfishing than most other fishes because they reproduce slowly.
"Some fish can release millions of eggs in a single day, but sharks give birth to litters of only a few young," he said.
"In some species, females only reproduce every second or third year. This means they can't sustain as much fishing pressure, their populations are slower to recover, and they're more vulnerable to extinction.
"This is the same reason that whales proved so vulnerable to exploitation. Humans stopped widespread whaling because their populations couldn't take it, but we're still exploiting sharks. Globally, we catch up to 100 million sharks per year."
Global FinPrint co-leader Dr Demian Chapman said the central problem existed in the intersection between high human population densities, destructive fishing practices, and poor governance.
The report highlighted what and where protection measures are likely to be most successful.
"We found that robust shark populations can exist alongside people when those people have the will, the means, and a plan to take conservation action," Chapman said.
Smith said any research into shark populations is a big step forward for the species.
"There is very little research on sharks in New Zealand – you'd be surprised at how easy it is to get to the limit of our knowledge," he said.
"You start asking questions about our sharks, and you'll very quickly get to the answer 'we simply don't know'."
