For marine researchers, drones serve a more significant purpose than just being cool gadgets. They’re part of the next wave of tracking marine life throughout the wild.
New research from North Carolina State University shows just how well consumer-grade drones work in keeping tabs on larger marine “megafauna” like sharks, rays, and sea turtles.
Tracking these keystone species remains critical, especially as climate change continues to affect life under the sea.
“We found that drones can be used to count and make species-level identifications of marine species, particularly in shallow marine environments,” said Enie Hensel, a Ph.D. candidate at NC State and first author of a paper on the work.
Benefits of drone-based analysis
Drones always had a knack for getting a bird’s eye view, but Hensel explained proving the validity of drones was more than justifying new research technology.
Previous research testing drones’ potential isolated the studies to a single site. A multi-site study, however, provided researchers with a greater understanding of what drones could do.
“Demonstrating the viability of drones for this work matters, because these are inexpensive tools for collecting accurate abundance estimates,” Hensel said.
“And those estimates are important for both informing the development of conservation efforts and for assessing the effectiveness of those efforts.”
“Drone surveys are also a good way to monitor shallow water, megafauna species because they are not intrusive,” Hensel continued.
“More traditional monitoring methods – such as boat surveys or gill nets – are more invasive, and have the potential to harm individuals or alter their movement patterns.”
Other monitoring methods involve tagging sea creatures to track their movements over time. Using drones to track the migration or activity of communities of these animals could cut down on the number of creatures being tagged each year for research purposes.
Testing drone tracking
The NC State team tested drones at several locations, all with different degrees of water clarity. To see just how well the drones performed, they put fake sharks in the water in various depths of clear and murky waters.
The team opted to use grey decoy sharks because they would prove the most challenging for the drones to spot.
“But we were able to spot them all,” Hensel said.
The researchers successfully spotted lemon, nurse, and bonnethead sharks. They also tracked southern stingrays and spotted eagle rays. The only hangup in identifying megafauna came from sea turtles.
While the researchers could make species-level identifications of the other creatures, they couldn’t differentiate between a hawksbill and a green sea turtle.
“One reason we chose these sites, all of which were on Great Abaco Island in The Bahamas, was because The Bahamas are interested in using several of the sites as a pilot for a managed conservation effort,” Hensel said.
“Our surveys provide baseline data for marine megafauna abundances within these newly established parks and we show that drones offer a new management tool for the park service of The Bahamas."
"And, of course, the technology certainly opens doors for us to explore a range of conservation issues," Hensel continued.