But this March, during an investigation of a 2005 shark attack in Australia, the shield’s effectiveness came into question after reports surfaced that a great white shark ate a chunk of bait hanging from a float carrying a prototype for surfboards. Could the electric field actually attract sharks? Rod Hartley, a co-founder of Shark Shield, says no and argues that the failed gadget was just a test unit with an undersize antenna. “Our final design works 100 times out of 100,” he insists.
Experts aren’t entirely convinced. Studies have shown that sharks will often turn away when they detect certain types of electric fields, says Christopher Lowe, a marine biologist at California State University at Long Beach. “But we also know that a highly motivated shark—one that’s rushing for prey, for example—can penetrate it.” And it’s important to note Shark Shield’s disclaimer: It works when the board is stationary but could be ineffective if the surfer is paddling or riding a wave.
It’s possible that the electric field only momentarily startles sharks, and scientists don’t think one device will repel (or attract) all species of sharks. “Animal behavior isn’t consistent in different conditions,” says Peter Klimley, an animal behaviorist at the University of California at Davis. “Anyone who says something works [with animals] 100 percent of the time is lying.”
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.