Shark Research

Dario Castillo at the URI Graduate School of Oceanography on Narragansett Bay

Dario Castillo, senior marine biology major and a National Geographic STEM field assistant, at the URI Narragansett Bay Campus

Photo credit: Nora Lewis

Senior marine biology major Dario Castillo spent the last five months conducting research on sharks and stingrays through a pilot program supported by the National Geographic Society.

As one of the first four National Geographic STEM field assistants, Castillo received funding to work with URI shark researcher Bradley Wetherbee while also receiving career guidance through weekly virtual meetings with National Geographic explorers and staff members. The program aims to provide support to students from under-represented groups interested in earning advanced degrees in the STEM disciplines.

“Meeting with other explorers and graduate students from all around the world and hearing what work they do with National Geographic pushed me to look for a graduate degree program,” said Castillo. “Not only have they advanced my thoughts about graduate school, but I’ve had the blessed opportunity to be guided by amazing grant writers to write a competitive National Geographic grant application. Receiving a grant is a way I can be globally recognized as a National Geographic explorer and join the global community of changemakers.”

“This program has been transformative for Dario and has been instrumental in paving the way for him attending graduate school and submitting grant proposals to support his research,” added Wetherbee. “Dario has risen to the challenge, working on boat engines, tolerating sea sickness during long days on the shark research vessel, and, most of all, conducting a comprehensive study of stingrays at Stingray City in the Cayman Islands.”

In addition to funding from National Geographic, Castillo’s research is also supported by the URI Science and Engineering Fellows program, which provides students from under-represented populations with interdisciplinary research experience addressing contemporary issues.

The first member of his family to attend college, Castillo is active in the URI student group BOND—Brothers On a New Direction—to encourage others like him to pursue higher education.

Sharks and stingrays

Dario Castillo with mako shark during his summer shark research project
Dario Castillo poses with a mako shark he captured during his shark research last summer. (Photo by Bradley Wetherbee)

Last summer, Castillo participated in shark research trips with Wetherbee into Rhode Island Sound, where they captured sharks of several species and attached satellite tracking devices to them to monitor their migratory movements. Some sharks were also tagged with accelerometers to determine the speeds at which they travel.

“The first time I went wasn’t so much fun because I was seasick, but we caught two or three sharks every time we went out, and I loved it,” Castillo said. “We caught mako sharks and blue sharks to learn about their migration and navigation.”

In between shark fishing trips, Castillo analyzed data about the southern stingrays that visit Stingray City in the Cayman Islands. He is writing a final report on his findings that he and Wetherbee hope will provide information for the tourist industry in the region that depends on the stingrays.

“We’re looking at the sex ratio of the stingrays that visit the main ecotourism area because the larger females seem to dominate,” he said. “We’re also trying to determine how long the stingrays are there each year and when they depart. The tourism industry wants to know how many stingrays are there because they attract a lot of tourists. The tourists feed the stingrays, and the stingrays disappeared from the area when COVID hit because tourists stopped coming and feeding them.”

The mysteries of the ocean

Castillo became interested in studying marine biology during family vacations to visit his grandparents in Florida, where he spent his time fishing and beachcombing.

“It’s the mysteriousness of the ocean that captured my interest,” he said. “We know more about the surface of the moon than we do about our own ocean right in our backyard. That’s what intrigued me at a young age. I want to explore what’s in the backyard.”

With just weeks to go before he graduates in December, Castillo is now applying to graduate schools in hopes of pursuing a career studying aquaculture and the diseases that affect oysters.

“Aquaculture has always been one of my interests,” he said. “And I’m fascinated with how genes can change and become more resistant to disease.”

—Todd McLeish