The Cayman Islands are the tops of an underwater mountain range called the Cayman Ridge, extending from the Cuban Sierra Maestra Mountain Range in the east to the Misteriosa Bank and Rosario Bank in the west, a distance of about 1,500km. The Cayman trench, the deepest part of the Caribbean Sea, extends to the south reaching depths over 7500m (25000 feet). With so little known about our oceans, and some of the deepest parts on the planet located in Cayman waters, exploring our deep sea to learn more about those environments and how marine species adapt in the face of increasing human impacts and climate change is a crucial step to navigating human health and well-being in a rapidly changing world.
A new shark research project led by Department of Environment (DoE) Shark Research Coordinator Dr Johanna Kohler, will start to reveal the deep diving behaviours and horizontal long-distance movements of Cayman’s Caribbean reef sharks with an aim to inform policy-makers about the importance of particular marine habitats to the survival of this ecologically important species. The more we can learn about Caribbean reef sharks, the better we can understand Cayman’s coral reef health, fisheries, and how ecosystem services might change in the face of climate change and an increasing human population.
“The project, launched in 2024, uses pop-off satellite archival tags which are basically small wildlife computers. Last summer, our Shark Research team including myself, research assistants Anne Veeder, boat captains and other volunteers, set out to tag eight reef sharks” explained Dr Kohler. “To our surprise, we caught quite a few blacktip sharks. The blacktip shark is one of the rarer species in Cayman and we don’t know much about them, so we decided to tag 5 blacktip sharks and 3 Caribbean reef sharks to collect data on the deep-diving behaviour of both and compare it. The tags continually collect and store depth, temperature, activity and light-level data. Then, on a pre-programmed date, the tags detach from the shark and float to the surface, transmitting the archived data to satellites.” In addition to tagging, the Shark Research team logged measurements and biological data such as the sex of the species and injury marks. Some of the sharks caught and tagged for the project had hooks in their mouths, evidence of previous encounters with fishers. “The hooks were severely rusted and would eventually fall out, but it still felt wonderful to remove these and release the shark in better condition than when we initially found them.”
10 years of shark protection and research
It was just 10 years ago, in early April 2015, when the Cayman Islands declared all shark species legally protected in Cayman waters. Since then, attitudes have slowly shifted a little further away from the fear and self-defence tactics sharks instinctively invoke, towards wonder and active preservation of these magnificent creatures. From a research perspective, much has been learned about shark species and behaviours in Cayman waters. While early shark research explored baseline information about shark populations in Cayman’s coastal waters, in 2022 the DoE’s collaborative work with Marine Conservation International, Beneath the Waves and Heriot-Watt University sought to map Cayman’s deep-sea environment using deep-water baited remote underwater video systems (BRUVS). This exploratory research revealed a number of significant new findings including both Caribbean reef sharks and a large school of Scalloped hammerhead sharks surprisingly recorded at depths of 200m (656 feet), and the first sightings of the Blurred lantern shark and Roughskin dogfish shark in Cayman waters. Acquiring the highly specialised equipment needed to study sharks is made possible with the support from various Darwin Plus grants and the donations from sales of Whitetip lager from the Cayman Islands Brewery.
The newly observed wide-ranging nature of Cayman’s Caribbean reef sharks raised particular concern of the degree to which they may be vulnerable outside of Cayman’s protective jurisdiction to both targeted and incidental fishing activities. Caribbean reef sharks are recognised as one of the top predators on coral reefs throughout the wider Caribbean and are pivotal to the health of reef ecosystems and the many benefits they provide to both people and planet. Since sharks generally avoid humans, variances in natural diving behaviour are likely influenced by impacts of human activities such as the increasing boat traffic and water sport activities in Grand Cayman. This, coupled with increasing sea surface temperatures and more frequent severe weather on our warming planet may be causing Cayman’s Caribbean reef sharks to seek refuge at greater depths or move away from Cayman into cooler regions.
Tagged & Tracked
Once filmmaker and Shark Research team volunteer James Dartnall learned about the shark tagging project and joined the first tagging expedition, he decided to merge his talent for film production and passion for the environment into a film documenting the trials and tribulations of this intensive work.
“What started as scientific documentation quickly turned into a passion project as I learned about all of the preparation and dedication that goes into the work. I was truly amazed by Dr Johanna and the Shark Research team’s expertise and attention to detail to not only physically execute the research but ensure its scientific integrity. I was immediately inspired to capture their engaging personalities and document the significance of this vital research.”
‘Tagged & Tracked: Shark Diaries of the Cayman Islands’ explores the challenges and triumphs of capturing, tagging, and releasing a live shark into the open sea and the subsequent harrowing work of gathering, analysing and reporting the data.
The documentary’s release comes just in time to celebrate the 10-year anniversary of shark protection in the Cayman Islands and will be screened for the first Cayman Shark Week, at various venues across all three islands from March 31st through April 5th.
• Monday March 31st – National Gallery | 530p arrival
• Wednesday April 2nd – Cayman Brac Beach Resort | 7p arrival
• Thursday April 3rd – Little Cayman National Trust | 530p arrival
• Saturday April 5th – Cayman Islands Brewery | 5pm doors open / 6pm start
Each evening will begin with a brief presentation followed by the film screening and Q&A with Dr Kohler and James Dartnall. All events are free with no reserved seating so audiences should plan to arrive early to secure their spot.
