Scientists Search for Elusive Giant Great Hammerheads

Legend has it that some of these sharks are 20 feet long.

Underwater shot of Erin Spencer with hammerhead shark (Sphyrna mokarran).
Researcher Erin Spencer with a hammerhead shark.

Duncan Brake / National Geographic

You’d think it would be easy to spot a gigantic great hammerhead

Researchers who study the behavior of these animals recently went on a quest to find some of the huge, elusive sharks. There have been reports about great hammerhead sharks (Sphyrna mokarran) that are as long as 20 feet, so researchers have long wondered how big these creatures can actually get.

The new program “World’s Biggest Hammerhead?” follows a team of scientists from Florida International University on an expedition off the coast of Florida and in the Bahamas as they see what they can find.

Candace Fields is a Ph.D. student at the university, studying large predators and her work is featured on the show. Fields talked to Treehugger about her interest in sharks and the challenges of studying them.

Treehugger: What is your personal fascination with sharks, particularly great hammerheads?

Candace Fields: Unfortunately, the media often depicts a negative picture of sharks, and for as long as I can remember I had always been drawn to sharks to figure out for myself why this was the case. I wanted to get my own perspective of these animals and understand their behavior firsthand with the goal of ultimately helping to change others’ perceptions of these beautiful animals.  

Researcher Candace Fields on location in the Bahamas
Candace Fields on location in the Bahamas.

Michael Potter / National Geographic

Growing up in the Bahamas, what is your background with animals and marine life in particular?

Being born and raised in the Bahamas, the ocean played a big role in my childhood. I would spend lots of time at the beach with my family however while they wanted to stay on shore I always wanted to snorkel and see any organism I could. I learned a lot of basic information about marine life because I was lucky enough to have the ocean easily accessible. 

Why are great hammerheads so hard to study?

Over the past few decades, the populations of great hammerhead sharks have declined significantly resulting in them being listed as a critically endangered species by the International Union for the Conservation of Nature (IUCN). As such, it is challenging to find and capture these animals in order to study these elusive animals. Further, these sharks have a low stress tolerance and so everything you do when studying them must be done extremely swiftly and carefully to ensure the safety and well-being of the animal.

What is the lore about how big these sharks can get?

Local lore indicates that these sharks can get up to 20 feet in length, however, a shark of that size has yet to be seen!

Why is it so important to study them?

As mentioned before, these sharks are critically endangered meaning they are one step away from being extinct in the wild. Because of this, information we can gather on this species, especially in terms of things like its movements and population structure, are critical to aiding in their conservation.

The underside of the mouth of a hammerhead shark
The underside of the mouth of a hammerhead shark.

Duncan Brake / National Geographic

What was it like on your recent expeditions in Florida and the Bahamas when you went looking for great hammerheads?

Like with any field work, the recent expeditions in Bimini and the Florida Keys had both high and low moments. There were a lot of long hot days, some of which with no sharks in sight but because we had an amazing team working together I had an amazing time. Additionally, being able to speak about and showcase shark conservation at home in the Bahamas was extremely rewarding.

You didn’t get to find and measure one that was as large as your team hoped, but what did you see?

We still saw two beautiful great hammerhead sharks in the water along with a tiger shark in Bimini!  Additionally, in the Keys, we were able to work up and tag four tiger sharks!

How important is a drone in studying these massive animals?

The use of drones gives us the capacity to study these animals in a non-invasive manner.  Using a drone, we are able to survey areas to see how many individuals of a species are present or the type of habitats they are using. Additionally, we can observe interspecies and intraspecies interactions that may otherwise be unobservable. 

“World’s Biggest Hammerhead” premieres July 18 on National Geographic. It will be shown on Disney XD on July 24 and Nat Geo Wild on Aug. 3.

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  1. Candace Fields is a Ph.D. student at Florida International University