Led by Dr. Austin Gallagher, the scientists of Beneath the Waves have been studying the sharks in the Bahamas for over a decade.
Estella and Arlyne are two female tiger sharks that have recently been tracked swimming over the deepest features of the Caribbean – the tongue of the ocean and the Exuma sound – and making dives to over 700 meters. The sharks spent a significant time at depth as well, with 20-30 minutes per dive spent in the twilight zone. This pinging on the satellite tracker was something the Beneath the Waves scientists had never seen before.
The incredible new-found behaviour sheds light onto the importance of deep water zones for sharks and shark conservation: “Sharks have been found to go to these depths before – but never in this region, nor have they gone to these depths with such frequency,” Dr. Gallagher states. “What is truly groundbreaking is that we had no idea that tiger sharks would be spending this much time in the twilight zone. This opens up a Pandora’s box of research questions and could reframe our conservation approach for this species.”
Exactly what were they doing down there? Future research missions are planned to help answer these questions, but early data from camera logging tags suggests there may be reproductive benefits to deep water habitat use. The tracks of Estella and Arlyne – both tagged just two months ago in the Bahamas Shark Sanctuary with high-resolution 45-day pop off archival tags – are profiled in the image below.
The tags collect depth temperature and location estimates and store them while attached to the animal. The attachment is minimally invasive and the tag will pop off after a pre-determined period, where the data is then transmitted to satellites in space and the scientists can access and download the information.
Tiger sharks are the largest predator in tropical ocean areas and can reach lengths over 20 feet. They are the true apex predator of the Caribbean and, despite being protected in the Bahamas Shark Sanctuary, they are still threatened by overfishing when they embark on their long-term migrations.
We need to make sure that these deep-sea sanctuaries remain intact and wild so that we can explore and better understand them.
“Interestingly, the Bahamas has many deep water features, and some of our previous work suggested this could be an important zone for these animals,” Gallagher elaborates. “By describing tiger shark habitat use in deeper waters, we might be able to determine if these may be suitable areas for the creation of marine reserves in the deep, or if tiger sharks can serve as shepherds to take us to new biological hotspots that are otherwise inaccessible without submersibles or remote vehicles.”
These recent discoveries are especially timely given the recent stream of information on climate crisis impacts and loss of biodiversity in the ocean. We know we are lacking information about many areas of the ocean, animal behavior, the riches of the deep sea, and what it all means for the healthy functioning of our planet. The Bahamas and a number of other countries have declared their waters to be shark sanctuaries and these safe havens are now spotlighting the secrets of the ocean. We need to make sure that these deep-sea sanctuaries remain intact and wild so that we can explore and better understand them.
And as for our adopted sharks, these animals are part of a large ongoing multi-year study investigating the residency of sharks in large-scale marine protected areas. Beneath the Waves plans to publish these results in scientific journals and has begun to engage with local and international stakeholders for sharing the data, actively looking for partners to support the expansion of the conversation of deep-sea exploration and conservation work in the region.
- This is a guest blog and may not represent the views of Virgin.com. Please see virgin.com/terms for more details. Kristin Hettermann is an ocean conservationist and underwater photographer who uses the camera and storytelling as tools to tap into emotions and elicit deeper feelings about her favorite part of planet earth, the ocean. Her artivism platform, OCEANSCAPES, is modeled to combine science and activism with art and design, and her favorite moments are in the field with scientists and naturalists exploring natural environments and capturing images that accompany their stories. Her mission is to inspire you to feel the ocean.