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the story of nemesis

Nemesis is a mature female great hammerhead shark who, up until late 2020/2021 season, migrated to Bimini for the winter and was a famous regular visitor to the hammerhead provisioning site. She was first identified in 2013, and had returned to Bimini every year from then on.


The Bimini Shark Lab has been researching the movements of these charismatic sharks for the past decade, and Nemesis' internal transmitter tag has provided valuable information on where great hammerheads are spending their time once they leave Bimini and the Bahamas Shark Sanctuary. Her annual migration had been very consistent, with her leaving Bimini in the spring and heading to the East Coast of Florida, making her way north as far as South Carolina in the summer, and returning to Bimini by December.

With the global pandemic hitting in March 2020, the hammerhead research season was cut short, and field work did not resume until the fall. As the water temperature cooled, the great hammerheads started to mark their arrival, however Nemesis did not return at all for the 2020/2021 season. Her last tag transmission was March 14th, 2020. 

Once leaving the Bahamas Shark Sanctuary, these highly migratory sharks face numerous threats including fisheries in other parts of the region. This highlights the importance of international cooperation for conservation of this critically endangered species.

 

We don't know what happened Nemesis, but we hope we will see her again.

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Nemesis

SPHYRNA MOKARRAN

IUCN RED LIST STATUS: CRITICALLY ENDANGERED

TOTAL LENGTH: 329.3CM


PIT TAG ID #: 900236000107365

SEX: FEMALE

AGE: APPROX. 20 - 25 YEARS 

TAGGING DATE: 11 APRIL 2016

FIRST SIGHTED: WINTER 2013 

LAST SIGHTED: MARCH 2020

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WHERE DID SHE GO?

The Bimini Shark Lab is using a series of Vemco acoustic monitors and tags to  better understand the movements, residency, and dispersal patterns of these sharks  (and several other species). There are currently 62 fixed-monitor stations positioned around Bimini and the surrounding areas. Additionally, there  are numerous cooperative acoustic receiver arrays throughout the Bahamas, east coast of United States, and Gulf of Mexico. Thanks to this cooperative array, we were able to keep tabs on Nemesis after she was tagged with a 10-year acoustic tag that transmits a unique identifying code every 90  seconds, which is recorded by any receiver within approximately 400 meters. 

Nemesis made a pretty consistent migration route from the time she was tagged until 2020. She spent the winter season in Bimini, then travelled north to South Carolina (2016, 2017, 2018, 2019) for the summer. On her way back to the Bahamas each year, Nemesis would spend time along the east coast of Florida for a couple of months, and then return to Bimini. 

After March 14th 2020, Nemesis was sadly not detected on any receiver within the Bimini or cooperative array.  

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