Drones Spot Sharks That Wander Too Close to Busy Beaches

It’s 8 a.m. on a sunny 84 degrees Fahrenheit Saturday at Alexandra Headland on the Sunshine Coast of southeast Queensland, Australia. Swimmers porpoise through the shimmering water, while farther offshore surfers straddle their boards in anticipation of the next big wave. If anyone is worried about a shark bite, you wouldn’t know it.

“Not really, probably should,” says 18-year-old surfer Jake Hazelwood of Cairns, a city farther to the north. “When you’re out there, you just zone everything else out.”

Hazelwood is also oblivious to the drone taking off from the beach just 65 feet away, the state government’s latest tool to help keep popular coastal areas safe for humans—and safe for sharks.

For decades, Queensland has relied on nets and baited-hook drumlines to help protect beachgoers from sharks. But that safety comes at a cost to marine life. Last year alone, that equipment caught 958 animals, including 798 sharks—70 percent of which died. Sixteen turtles also perished as unintended victims along with 10 dolphins and two dugongs, a vulnerable species in Queensland. And in 2022, 15 humpback whales were caught in shark nets, though all of them were safely removed.

The government is considering replacing its lethal measures with using camera-equipped drones to search for sharks, and Alexandra Headland is one of the locations for a trial program that is already showing success.

It’s surprisingly easy to spot sharks when you fly over them, says Rob Adsett, the chief remote pilot with the Australian Lifeguard Service. “Technology is getting better.”

The infrared-equipped drone that Adsett and his colleagues used off Alexandra Headland can fly for 20 minutes in winds above 21 miles per hour. The pilots fly the drone along a 1,300-foot route parallel to shore behind the surf break. On busy beach days, the drone zips along at up to 12.4 miles per hour, staying out of the way at an altitude of 195 feet. When pilots detect a shark, they lower the drone to just below 100 feet so they can identify the animal’s size and species, a task that can become more difficult when it is raining or if the water is murky or rough.

If the pilots deem the shark a danger, they can evacuate the beach while lifeguards follow in inflatable boats or personal watercraft to track the animal and monitor the threat.

During their trials in 2020 and 2021, which involved 3,669 drone flights at seven beaches, drone pilots detected 174 sharks, including 48 that were greater than 6.5 feet in length. For beach users and lifeguards, the presence of big sharks, especially white, tiger and bull sharks, is the greatest concern, and these sightings led to four beach evacuations.

Queensland’s effort is following on the heels of a similar project that has been underway in New South Wales, the state just to the south, since 2017.

For conservationists, the switch away from nets and drumlines can’t come soon enough. Any further delay in removing the lethal deterrents “is baffling,” says Leo Guida, a shark scientist with Australian Marine Conservation Society. “They’ve got the solution on the table.”

Drones, says Guida, can also save people by dropping life-saving equipment to someone struggling in the water. “You’re more likely to save someone from drowning than interacting with a dangerous animal,” he says. “There are clear benefits across the board” to having drones at the beach.

The toll of the nets and drumlines on sharks also has to be balanced against the threat sharks actually pose to beachgoers. According to Adsett, “You’ve got more of a chance of getting hit by a car on the way to the beach than getting attacked by a shark.”

Still, shark bites do happen. Though infrequent, bite rates are increasing.

The Australia Shark Incident Database recorded 1,196 shark bites in the country over the past 231 years, from 1791 to 2022. Those bites caused 250 deaths, while 723 people suffered injuries. No one was injured in the other 223 cases, which cover incidents such as bites to surfboards.

Shark bites jumped from an average of nine per year in 1990-2000 to 22 per year in 2010-2020, in part because of the increasing human population along the coast.

But even nets and drumlines, Guida argues, are no guarantee against bites because sharks can simply swim around them. That’s what happened in 2020 when a male surfer in Queensland died after being bitten at Greenmount Beach, a stretch of coastline equipped with nets and drumlines. As for whether the nets can be replaced with drones, the Queensland government has at least seen enough to continue their trials. They’ve committed to expanding the project, which will continue through June 2025 at a cost of roughly U.S. $1.3 million per year.

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

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