The Search for the World's Biggest Hammerhead Shark

Scientists have been on a mission to find the world's biggest hammerhead shark.

The National Geographic expedition—which was filmed for Sharkfest 2022 documentary World's Biggest Hammerhead—follows a team of scientists from Florida International University who embark on an expedition to find the elusive predator.

Huge great hammerhead sharks have been spotted off the Florida coast before. Some of them are rumored to be similar to the great white shark in size, reaching up to 20 feet in length. The biggest hammerhead ever found was caught by a recreational angler in Florida, and measured 14.5 feet long, and weighed 1,282 pounds.

However scientists are still unsure just how big these sharks can get. In the film, scientists travel along a great hammerhead migration route, from the Florida Keys to the Bahamas, in a quest to find out.

Candace Fields, a Ph.D student studying geographic and population dynamics of large predators at Florida International University, was part of the team.

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A picture shows the underside of an 11 foot hammerhead. Scientists were searching the world's biggest one. National Geographic/Duncan Brake

"Generally, what people see of shark science is all the glory and excitement right but a lot of this work is just sitting and waiting and nothing happening. And so it does get frustrating, but it's a game of patience. But because there's so few, when you do see one, it is very thrilling, very exciting and very encouraging," Fields told Newsweek.

Fields said the species is infamously difficult to spot, mainly because they are critically endangered. Main threats on the species include being caught as bycatch by fisheries— and this in turn makes them more difficult to find for scientists, who want to conserve the population—as they can become smart to capture techniques.

"[The hammerhead] is one step away from extinction in the wild," she said. "One of the challenges of catching these guys is just there's not as many of them out there as there are other species. Also, some of them have become smart to capture techniques. If it's an older animal that might have been caught a couple of times, they do learn... they do become aware of the hooks and try to avoid them. Really, they're just very elusive animals in general and then, coupled with the fact that they're critically endangered makes it very challenging to find them."

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Researchers are pictured next to the 11 foot hammerhead. They were aiming to collect data on the species. National Geographic/Duncan Brake

Fields said the larger hammerheads also play a vital role in the ecosystem, which is why it is important to gather data on them: "Any information that we can gather on these critically endangered animals is crucial to their conservation and our ability to conserve them in terms of ecological roles.

"There's a lot to learn about these animals, especially about larger individuals, as they're often not caught with high frequencies. They are top predators, so they keep balance in terms of capturing their prey ... weaning off sick animals and things like that. There's a lot of things that they are important for."

Gathering data on the species is also important for their overall reputation, Fields said.

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A picture shows the underside of a Hammerhead, with a row of sharp teeth.The predators are important to the wider ecosystem. National Geographic/Duncan Brake

She believes hammerheads are misunderstood due to their unusual appearance: "They are more intriguing to people and so people think, oh, they're different. And I've heard 'but aren't hammerheads aggressive'? Are they really likely to attack you? And that's just not the case. And so I think, I hope that in highlighting hammerheads, people can understand their biology."

The scientists were not able to find a hammerhead exceeding this one during the expedition. However, they did spot an 11 foot hammerhead swimming in Florida, while another was spotted swimming off the coast of the Bahamas, using a drone.

Fields said capturing the sight of one on a drone was "super cool," as it showed the shark swimming in the shallows, really clearly in a "non-invasive manner."

"And so it just gives you a little bit of a spark again, to not quit even though you're having a tough day out," Fields said.

The 10th anniversary of SharkFest kicks off July 10 on National Geographic and Disney+. World's Biggest Hammerhead premieres July 18 on National Geographic.