Doctoral student protects Galapagos’ sharks

At 5 p.m., as the sun begins its descent, Savannah Ryburn embarks on her workday. A doctoral student in the College of Arts and Sciences’ environment, ecology, and energy program, Ryburn has spent the past five years dedicated to studying the diet of juvenile blacktip and scalloped hammerhead sharks in the Galapagos Islands.

Despite the setting sun, her workday is just beginning. Over the next 24 hours, she will be on a boat, meticulously tracking one of the Galapagos' elusive juvenile scalloped hammerhead sharks, a species on the brink of endangerment. Using a hydrophone that detects signals from an acoustic tag attached to the shark's fin, she navigates the boat to stay in close proximity to the shark, recording its movements. With only a brief nap around 5 a.m., interrupted by a pelican roosting on her head, she remains vigilant without sleep.

This tracking project, where she successfully maintains the shark's trail, underscores Ryburn's unwavering commitment to her research. Her dedication became evident earlier when, in the summer of 2022, she, along with Galapagos National Park staff, discovered a new nursery bay for juvenile scalloped hammerheads on Isabela Island after two weeks of exploration. This discovery, crucial for both Ryburn's research and the broader understanding of shark habitats in the Galapagos, followed her relentless pursuit.

Ryburn's research not only showcases her dedication but also her humane approach to studying this endangered species. Unlike traditional methods that involve killing and dissecting animals for diet analysis, she employs metabarcoding, a cutting-edge technique. This allows her to study the diets of her sharks without harm. In just two minutes, she completes a workup of each shark, taking basic measurements, swabbing the cloaca for a fecal sample, and then safely releasing the shark back into the water. The subsequent metabarcoding analysis, conducted in labs at the Galapagos Science Center and UNC-Chapel Hill, provides detailed insights into the sharks' diets at the genus and species levels.

Through this method, Ryburn has maintained a remarkable record of no scalloped hammerhead shark deaths during their interactions. Her meticulous approach enables her to discern the dietary habits of both scalloped hammerhead and blacktip sharks down to the species level.

Given the critically endangered status of the scalloped hammerhead, Ryburn emphasizes the importance of her innovative method. She envisions her data contributing to practical conservation measures for these shark species, including targeted fishing restrictions to protect the fish in their diets. While enforcing fishing restrictions across the islands poses challenges due to local dependence on fishing for livelihoods, Ryburn's metabarcoding method allows the Galapagos National Park to create rules that specifically limit fishing of the species consumed by her sharks, fostering coexistence between fisherfolk and sharks.

Reflecting on her research, Ryburn finds it extremely rewarding, citing the privilege of working with a critically endangered species rarely seen by the world. Her work provides a unique opportunity to contribute to the conservation of these remarkable creatures.