Pigeon Key Creature Feature: Hammerhead Shark

Many visitors come to Pigeon Key hoping to catch a glimpse of one of the kings of the Keys. And although it once reigned supreme in our blue waters, the Great Hammerhead shark (Sphyrna mokarran) faces its toughest battle yet as its population plummets.

The Great Hammerhead’s wide cephalofoil head and large size makes them a favorite among our Pigeon Key guests. They are only beat by the Great White for the title of largest shark found around the Keys. Hammerheads regularly measure 20 feet long and 1,500 pounds. So, why do they call South Florida their home?

Every spring, hammerheads follow swarms of tarpon up from the Caribbean to feast. Your favorite fishing season may be the same as these giants. Hammerheads also enjoy squid and small sharks, but their favorite food is what brings them back to the Caribbean: the stingray. They can eat dozens of stingrays without being bothered by their sharp spines. One hammerhead in South Florida was found with 96 stingray barbs in its stomach!

Hammerheads use their large cephalofoil head to trap the rays down before dining. Scientists believe that this is a learned behavior – an added advantage – of the cephalofoil. They say that the relatively modern hammerheads evolved with a large head to enhance their sensing abilities.

All sharks have electronic sensors called Ampullae of Lorenzini in their nose and head. The sensors detect electromagnetic pulses from other living things, allowing sharks to be effective predators. The hammerhead’s extra-large head gives it more surface area for detecting, and helps it find even the most camouflaged rays. It also explains why hammerheads swim in a sweeping motion like a metal detector.

Although every adaptation makes them an apex predator of the ocean, hammerheads are not a huge danger to humans. According to the International Shark Attack File, there has been 17 unprovoked hammerheads attacks since 1580. None of them were fatal. For sharks overall, there is an average of 100 documented shark attacks every year. Compare this number to the 100 million sharks harvested annually by humans, and you can see we have an unfair advantage.

Hammerheads are especially hunted for their elongated dorsal fins that make them easy targets for finning. Countries around the world harvest shark fins to make shark fin soup, and leave the rest of the shark to drown. People also fish hammerheads for game, out of fear, and on accident.

Because of this, in 2018, the IUCN listed the Great Hammerhead as critically endangered. Their populations are rapidly decreasing, yet there are no action or management plans on the federal level. Florida Fish and Wildlife Commission made it illegal to harvest them in 2012. And in July of 2019, Florida required any kind of shark fisherman to obtain a permit and take an online class educating them on safe fishing practices.

For now, hammerhead numbers continue to fall as humans decimate their populations. We at Pigeon Key hope to see the kings of the keys for years to come, and hope others will join our fight to protect an amazing species.