Each summer, thousands of people flock to the surf beaches of California and Australia, eager to catch one of the Pacific’s classic waves. But they likely don’t realize that they’re sharing the water with growing numbers of great white sharks congregating offshore.
The phenomenon has been confirmed using drone technology, which is transforming shark research with its ability to give scientists a bird’s-eye view of the animals inhabiting the world’s coasts.
Drone observations often can reveal more than Earth-bound research methods about shark movements, feeding habits, social relationships, and the animals’ reactions to people in their habitat. (Read how sharks form years-long friendships.)
“When we started out, we weren’t even sure whether drones could be used to do studies like this, but in just a few years they’ve become a critical tool,” says Paul Butcher, senior shark scientist for the Australian state of New South Wales and lead author on a study about the “drone revolution” in shark science.
Butcher and his team operate a drone-monitoring program that launched in 2021. “We now have drones flying at all 51 surf beaches in Australia on weekends and school holidays during the summer season,” Butcher says, and the devices regularly spot shark species such as hammerhead, nurse, bull, mako, and great whites off New South Wales, including Sydney’s famous Bondi Beach.
In California, drone observations show that great white sharks, drawn by abundant food and waters warmed by climate change, are gathering along the coastline in growing numbers, says Chris Lowe, director of the Shark Lab at California State University, Long Beach. In 2020, Shark Lab tagged 38 white sharks, three times the number seen the previous year.
The predators, which are listed as vulnerable to extinction by the International Union for Conservation of Nature, have rebounded in recent years under the protection of a state-imposed fishing moratorium.
“The great thing about drones is that they give us this beautiful aerial perspective of what individual sharks are doing in the moment,” says Lowe. “People don’t know this is happening—they can’t see this eight-foot shark swim right underneath them—but we get to see these sharks interacting with people on a daily basis.”
That’s also why drones are so vital to public safety. Several local governments in Australia and California regularly deploy drones over beaches during the summer to keep track of shark activity, allowing them to decide quickly whether swimmers should be warned or, more rarely, if a beach should be closed.
Using drones to monitor beaches is so important that the state of California recently allotted $3.75 million to Shark Lab to monitor the increasing numbers of sharks and learn more about how to help beachgoers interact with the growing population safely, Lowe says.
Shark incidents—defined as any time a shark approaches and touches a person or surfboard in the water—are rare, with just 202 recorded in California since 1950, according to the state’s Department of Fish and Wildlife. What’s more, while the number of beach swimmers has grown along with California’s population, shark incidents haven’t increased proportionally.
A new perspective on sharks
Observations with drones also have produced new scientific findings about the ocean’s top predators.
Shark Lab’s drones, for instance, have shown the great majority of the white sharks gathering off Southern California are juveniles no more than 10 feet long.
“Juvenile sharks are too small to efficiently maintain their heat, so that’s why you see them closer to shore,” says Emily Spurgeon, a graduate student in the Shark Lab. “They’re still massive animals, but they’re just babies coming into shore to get warm and stay safe and find food.”
In Cabo Pulmo National Marine Park in Baja California, researchers have used drone footage to distinguish lemon, bull, and Pacific nurse sharks crowded together in the shallow waters, an experiment that demonstrated drone footage is accurate enough for species identification.
Drones also enabled scientists in the Seychelles to unobtrusively monitor tiger, bull, and tawny nurse sharks scavenging a sperm whale carcass. That led to the surprising discovery that the three shark species dined simultaneously in relative peace, without fighting to establish a hierarchy.
Drones go sci-fi
As drones and their video cameras becoming increasingly sophisticated in coming years, scientists expect to learn even more about shark behavior.
Already, automation allows drones to fly in any weather, with no need for a human pilot. And artificial intelligence (AI) systems can scan aerial images in real time to detect sharks and identify species, providing instant alerts for beach visitors.
Technology companies including Fujitsu and Salesforce are partnering with researchers, in collaborations known as Sci-eye and Sharkeye, to develop algorithms that can identify numerous shark species under many different climatic and ocean conditions in real time.
While drone observation systems are deployed with a focus on protecting people, they play a critical role in helping sharks, too. For example, Butcher says that drones offer a humane alternative to shark nets, which Australia’s local governments have used since the 1950s to physically keep sharks away from beaches.
These large nets, installed about 1,500 feet from shore, can ensnare and harm smaller sharks as well as dolphins and other animals, including endangered species.
“It used to be that people just said, ‘Let’s get rid of those animals,’” Butcher notes. “Now they still want protection, but they want programs that don’t have adverse effects” for the sharks.
Sharing the waves
Spurgeon and Butcher also hope their drone research can dispel some misperceptions about sharks, which have been swimming Earth’s oceans for 400 million years.
“The greatest myth that we’ve found during our current research is that everybody thinks there are local sharks sitting off their beaches,” Butcher says.
“But what we’ve shown is that sharks move great distances”—sometimes more than 120 miles a day, he says. “So if you see a shark off your beach on any given day, you can guess that it’s going to be a long way away by the next day.”
In California, Shark Lab’s drone-monitoring program also includes some beachside outreach, such as reminding the public that sharks need not pose a threat to humans if carefully monitored.
“People hear about sharks close to shore and they think they’ve come for people, but all they’re looking for is stingray,” says Spurgeon. “And they’re so easily scared—we have footage of a shark being spooked by a piece of kelp.”
In the final analysis, Spurgeon says, “All of our efforts are both about protecting the public and about raising awareness that people are sharing an important habitat with these baby white sharks.”