From a nature lover’s perspective, it is a wonder to be in the water and have a seal pop up, or see a gray streamlined body shoot by in pursuit of fish. But the reality is the seals are being hunted as well and great white sharks have repeatedly been spotted in very shallow water near shore, even attacking seals close to where people swim and surf.
“Their movements are really dynamic and they can be very, very close to shore, within range of anyone who is swimming,” said state Division of Marine Fisheries shark researcher Greg Skomal. Seeing them in shallow water is not an anomaly, Skomal said. “We’ve been seeing them there right along.”
Long Beach, California, Marine Safety Chief Joe Bailey had a similar shark problem. Although they’d never had any confirmed great white sightings along the 13/4-mile stretch of beaches he oversees, earlier this spring Bailey received a video showing a couple of sharks in the breakers at Surfside Beach. Local shark expert Chris Lowe of California State University at Long Beach, identified them as juvenile great whites.
According to their shark policy, Bailey had to post a warning as long as the sharks were present. He sent a pair of lifeguards out each day on a personal watercraft to see whether the sharks were still there, but that tied up valuable personnel for hours, and often they weren’t high enough off the water to view beneath the surface glare to depths where great whites spend the vast majority of their time。
That’s when Bailey decided to go with a drone.
In a half hour, his crew could drive down to the beach, launch the quadcopter and take a video survey of the water that played out live on a tablet on shore.
The drone flies at 150 to 170 feet. If the spotter watching the screen sees a dark spot, the controller flies lower to get a close-up. While Lowe believed the sharks would leave after a couple of weeks, in over a month of surveillance flights, the drone has found great whites, sometimes as many as a dozen, in the shallow waters where waves are breaking. After reviewing the footage, Lowe told him they were all juveniles that were too small to hunt seals and therefore unlikely to attack humans.
Bailey could post warnings, but did not have to close beaches.
“In all the time I worked here, we never had a confirmed sighting of a great white shark, but now with the drone we know they are there,” Bailey said. “A big part of my job is education, like educating people to the dangers of rip currents. I feel like the shark thing is the same thing. Sure, people say they don’t want to know they are there, but from our perspective a better educated public is the way to go.”
Vincent Harris, an electrical and computer engineering professor at Northeastern University, said drones are a good, and relatively inexpensive, way to patrol the Cape’s beaches as well. “My personal feeling is that drones are here to stay,” said Harris, who does classified research on drone technology for the military. “They will use them routinely at beaches (that have) shark visits and attacks,” he added.
Harris said researchers at Northeastern were already at work on software that would allow the drone to differentiate sharks from other marine species and alert marine safety personnel. It may take another three to five years of research and testing, but a pattern recognition program could allow a drone to fly a predetermined route on its own looking for shark shapes. When it finds one, the drone would drop down for a closer look and send an alert to a beach administrator and lifeguards who could see the shark up close on a laptop or smartphone, know its location, and make a decision on whether it is a threat or just passing by.