The Great Hammerhead

 About

The great hammerhead shark (sphyrna mokarran) is the largest of all hammerhead shark species. There are nine species of hammerhead shark and seven of which are endangered. As of 2021 there was an estimated 200 great hammerheads left in the wild.

It can grow up to twenty feet in length. Great hammerhead sharks have a long rectangular shaped heads with an indentation in the middle—this feature distinguishes them from other species. Their heads have electrical receptors that can sense their prey. Sharks are apex predators, and the hammerhead is no exception.

Great hammerhead sharks can be found in coastal to open waters worldwide—water that is 68 degrees (Fahrenheit) or higher. This species of hammerhead is solitary, they migrate distances over 765 miles alone. 

Habitat role

Great hammerheads are primarily bottom feeders. The sea floor is where they find their prey. They eat stingrays, octopus, squid, crustaceans, and other sharks. Great hammerheads don’t eat anything bigger than stingrays and because these sharks are so large, they aren’t preyed upon by other ocean animals. Being at the top of the food chain, great hammerheads play an important role of maintaining coastal marine ecosystems. By preying on the species below them in the food chain, these sharks help maintain species diversity. Without great hammerheads, the specific marine life they eat would grow immensely in population.

Threats

Humans are the cause of the great hammerhead shark’s critically endangered status. They are victim to:

·       Fishing

·       Fishing nets

·       Poaching

Threatened by overfishing, and getting accidentally caught in coastal longlines, gillnets, trammel nets and sometimes trawls, particularly in areas with narrow continental shelves, humans pose a great threat to these sharks. According to the iucn red list, “The post-release mortality is higher for injured released sharks and has been reported as 100% for the closely-related Scalloped Hammerhead.” People who catch sharks when fishing may think they have good intentions because they plan to release it once they get a picture. But great hammerheads are known to die even while they are still on the line. Fishing is deadly for them.

Great hammerheads are greatly threatened by the shark fin trade because of the large size of them. Even if they are still alive after their fins are cut off—they will not survive after being thrown back in the water.

Why care?

According to fossils, sharks have been around for more than 400 million years. They outlived dinosaurs which makes them a pretty special animal. On the International Union for the Conservation of Nature’s “Red list,” 143 species of shark are listed as “endangered” or “critically endangered” “near threatened” or “vulnerable.” Overfishing and lack of regulation is a problem that can be solved by humans. In 2013, a study discovered that 97 million sharks were caught and killed by fishermen in 2010.

Given their critical condition, it is surprising that not more is being done. The Weather Channel posted an article in March of 2021 about a Texas fisherman who caught a 14-foot hammerhead shark. The shark did not survive the release. This could’ve all been avoided if the man decided not to catch the shark. The rest of the article along with pictures can be accessed with this link: https://weather.com/sports-recreation/fishing/news/2018-07-17-texas-hammerhead-shark-controversy-endangered

Great hammerhead sharks are known for feeding on the ocean floor. They are immune to stingray and catfish barbs, unlike other animals. As the apex predator of bottom feeders, once the top predator is gone, there are no more regulations for the prey. It is important to the balance of our marine ecosystems that sharks continue to live on.

What is being done?

The short answer…not enough. But this is what has been going on.

·       The great hammerhead is protected from commercial and recreational harvest in Florida waters.

·       Conservation biology study on a great hammerhead nursery on the Atlantic coast of the United States. https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/csp2.418

·       Bimini Biological Field Station Foundation: research project combining telemetry and genetic data as well as the shark’s use of space in order to examine conservation. https://www.biminisharklab.com/hammerheadconservation

·       Listed on Annex I, Highly Migratory Species, of the UN Convention on the Law of the Sea, this tells other states that all should be working together to manage the species.

·       The Australian Marine Conservation Society is working on protecting hammerheads from fisheries and shark control programs. They are also trying to ban Australia’s import and export of shark fins. https://www.marineconservation.org.au/save-our-sharks/

       

        Conservation through geography 

        I think that conservation planning with the use of geographic tools would be the most helpful to the great hammerhead. The Geographic Information System (GIS) could be used to assess the waters for nursery area. Great hammerheads are only fertile every two years, so the survival of their young is very important. With the geographic information, the nursery area of the hammerhead can be protected and restricted from any kind of fishing activity. Geography can help map hammerhead shark migration patterns because they don’t stay in one place. By understanding where these sharks go and the places that it frequents, we can prioritize the conservation of certain areas instead of a more general plan.

        Make a difference!

        *do not participate in shark fin trade!*

        *do not fish for sharks!*

·       Tell the house of representatives to ban the trade of shark fins in the USA—click this link https://act.oceana.org/page/99352/action/1?_ga=2.205491031.652260775.1653336483-366998922.1653336483

·       Sign the petition to end live finning in Australia—click this link https://action.sharkchampions.org.au/page/51322/action/1?ea.tracking.id=AMCS

·       Support Bimini Biological Field Station Foundation https://www.biminisharklab.com/support-us

·       Spread the word about shark fishing and shark fin trade. Make sure the people that you know do not contribute to the extinction of the great hammerhead!