The Great Hammerhead is one of the world’s most iconic fish species.
It is the largest of all hammerhead sharks (capable of growing to almost 20 feet in length) and is found across the globe in tropical and warm temperate waters in depths of up to 1,000 feet. The species is highly mobile, with some individuals making yearly thousand-mile-long migrations for feeding and breeding purposes.
Great Hammerheads listed as critically endangered
Unfortunately, the species has seen sharp global declines over recent decades, which has resulted in Great Hammerheads being listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) in 2018. Some of the primary reasons for their decline include illegal shark finning and high bycatch mortality. While Great Hammerheads aren’t generally targeted by commercial fishing in U.S. waters, when hooked by commercial longlines, they commonly die from stress and exhaustion before they even reach the vessel.
Sea Grant to contribute data for stock assessment
Thankfully, it is not all doom and gloom for Great Hammerheads. As a result of recent management measures, there is evidence that Great Hammerhead populations may slowly be recovering in U.S. waters. In fact, this year Atlantic hammerheads (a group that includes Great Hammerheads, Scalloped Hammerheads, Smooth Hammerheads and Carolina Hammerheads) will undergo their first SouthEast Data, Assessment and Review (SEDAR) stock assessment.
To aid in this assessment, marine fisheries specialists with the Mississippi-Alabama Sea Grant Consortium will be contributing data, such as catch trends, as well as vertebrae for ageing and fin clips for genetics.
In addition, MASGC specialists are collaborating with Mississippi Aquarium to tag Great Hammerheads with fin-mounted satellite tags. Any time one of these tagged hammerheads swims near the surface and its fin breaks the water, the tag will communicate with above satellites and relay the shark’s current position to us in real time.
From these data, we can learn more about how far these Great Hammerheads travel in a given year and what times they are moving the most – information that’s critical to understand for a species that is known to cross international boundaries. These data can also indicate which areas of the Gulf are most commonly used by Great Hammerheads, enabling us to inform managers of areas where the species may be vulnerable to exploitation.
If you are interested in seeing where these Great Hammerheads journey after we tag them, be sure to check out the Mississippi State University Marine Fisheries Ecology Facebook page. One shark has already been tagged this year, and we hope to tag several more, so keep an eye on our social media page as we share their movements going forward.
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