Drones can help find, count marine megafauna: Study

Consumer-grade drones may effectively monitor marine species in the wild, say scientists, offering a valuable platform to study populations of sharks, rays, sea turtles and other megafauna.

"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 PhD candidate at North Carolina State University in the US.

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

Those estimates are important for both informing the development of conservation efforts and for assessing the effectiveness of those efforts, according to the study published in the Latin American Journal of Aquatic Research.

Drone surveys are also a good way to monitor shallow water, megafauna species because they are not intrusive, researchers said.

"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," said Hensel.

Previous studies using drones to monitor marine species have focused on single sites.

The recent work evaluated multiple sites, demonstrating that drones can be used to assess environmental variables that may be responsible for population differences between locations.

For example, drones may be used to help target conservation efforts on sites that have the most value in terms of supporting specific species.

The researchers also showed that drones are effective at sites with varying degrees of water clarity.

To assess the effectiveness of the drones, researchers placed fake sharks underwater at two sites with different water clarity. Drone footage allowed researchers to identify all of the decoys at both sites.

"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.

In field testing, researchers were also able to make species-level identifications of lemon, nurse and bonnethead sharks, as well as southern stingrays and spotted eagle rays.

The drone footage also allowed researchers to identify sea turtles, though they had difficulty differentiating between hawksbill and green sea turtles.