New gadget makes use of electrical fields to scare sharks away from hooks

A new device uses a shark’s sixth sense to repel fish from deadly hooks.

Sharks, rays and their close relatives can detect tiny electric fields thanks to a bulbous organ concentrated near their heads called the ampulla of Lorenzini. So the researchers developed SharkGuard, a cylindrical device that attaches to a fishing line directly above the hook and emits pulsed short-range electric fields.This Device successfully deters sharks and rays, which may have temporarily overwhelmed their sensory systems, the scientists said in a Nov. 21 report. current biology.

While many people are afraid of sharks, this fear makes more sense in reverse.many shark species are endangeredMainly due to human activities (Serial Number: 11/10/22).

A major problem for sharks and rays is bycatch, the creatures that are accidentally caught by fishermen while fishing for tuna and other fish, says David Schiffman, a marine biologist and faculty researcher at Arizona State University in Tempe ( David Shiffman) said.

Whether the electric field generated by the SharkGuard device will repel or attract sharks and rays is an open question. When hunting, these animals use their extra senses to detect tiny electric fields emitted by their prey. So Rob Enever, a marine biologist at conservation engineering firm Fishtek Marine in Dartington, UK, and his colleagues sent two fishing boats in the summer of 2021—both equipped with some ordinary hooks and some with SharkGuard’s hooks – and let them catch tuna.

In short, Shark wants nothing to do with SharkGuard gadgets. Video shows the blue shark using SharkGuard to approach the hook and turn away with no apparent injuries. Encountering an unpretentious hook, the shark takes the bait and becomes bycatch.

Hooks with electric repellants reduce catch rates of blue sharks (frog) was reduced by 91% compared to standard hooks, from an average of 6.1 blue sharks caught per 1,000 hooks to 0.5 sharks. Pelagic stingrays decreased by 71% (pterosaur) were captured using SharkGuard hooks, ranging from an average of 7 rays to 2 rays per 1,000 hooks.

A typical fishing vessel used in the study had about 10,000 hooks. So, if a boat’s entire set of hooks were equipped with SharkGuard, it would be possible to catch anywhere from 61 blue sharks to 5, and from 70 pelagic rays to 20.

If those numbers were scaled up to the millions of sharks and rays that are accidentally caught each year in longline fisheries, Enever said, “these pelagic shark populations would recover massively.”

“It’s definitely a dramatically significant effect,” said Schiffman, who was not involved in the study. “if [the devices] In effect across the entire fishing fleet that interacts with blue sharks, this is [them]”

But that doesn’t mean SharkGuard is ready to roll out. The catch rate of tuna in this study was generally abnormally low, making it impossible to say for sure whether tuna would also be troubled by the device. If so, there would be no point for fishermen to use the equipment in its current form.

The team is also working to make SharkGuard smaller, cheaper and as manageable as possible so fishermen can “fit and forget” it. For example, batteries that currently need to be replaced every two weeks will be replaced with batteries that can be charged inductively when the fishing line is not in use, “basically like a toothbrush,” Enever said.

Shiffman would like to see SharkGuard tested in different environments and with other types of sharks. “There are a lot of shark species caught as bycatch on these longlines,” he said.

While the invention seems to be working so far, no technology can be a silver bullet for shark conservation. “Tackling bycatch requires many different solutions working together,” Schiffman said.

A solution is urgently needed. “We’re in a situation where many of our pelagic species are either critically endangered, endangered or vulnerable,” Enever said. But the new findings are “the true story of ocean optimism,” he said. They show that “there are people out there … trying to fix these problems. There is hope for the future.”