Drones have been used for many things in the last few years, from taking selfies to search and rescue missions, to military uses. Now a team of researchers and developers from North Carolina State University has found a new use for drones: tracking sea animals.

There are many recent examples of ocean pollution affecting marine life, such as sea animals dying from eating plastic. How animals are navigating life in an increasingly polluted environment has been of great interest for conservationists and scientists. Traditionally, scientists tag a sea animal and release it back to the wild. The scientists monitor the tag for data on the animal and its community, if it has one. But this method has limitations. Tags can be unreliable and data on an individual creature doesn't always correlate to its pack.

The North Carolina State researchers have successfully tested drones to track packs of sea animals in multiple sites with varying water clarity. Drones can also find the environmental variables that are affecting the populations of the animals, without disturbing the animals in a catch and release mission.

NC State researcher Enie Hensel operating a drone at a research site in The Bahamas. (Source: Duncan Brake)

"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. “Demonstrating the viability of drones for this work matters, because these are inexpensive tools for collecting accurate abundance estimates. 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. 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."

The team conducted a series of tests to find just how effective drones are at tracking animals in the water. Testing proved that the drones could track animals even in murky water. The team placed fake sharks in two different areas with varying water clarity. They then sent a drone out to find and track the fake animals. In both experiments, the drone was successful.

"We chose grey shark decoys because they would be the most difficult to spot in these environments, but we were able to spot them all," Hensel said.

During testing, the drones were also able to identify specific species of animals. The drones found and identified lemon, nurse and bonnethead sharks, southern stingrays and spotted eagle rays. The drones could also identify sea turtles, but it couldn’t identify different species. The team says that could be fixed with more programming.

"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."

The paper on the drone study was published in Latin American Journal of Aquatic Research.