Millions of sharks, rays, and skates are accidentally killed every year as bycatch within the global fishing industry—an especially staggering number when considering that a quarter of all those species are currently considered endangered. Previously, fishers could do very little to discourage the predators from going after the longline bait meant for intended targets like tuna, but a simple and ingenious new technology is showing huge promise in finally changing course. Highlighted via a study published earlier today in Current Biology, a small device dubbed SharkGuard recently decreased the number of unintended shark catches by as much as 90 percent through exploiting one of the animals’ most impressive senses.
The premise behind SharkGuard is relatively simple, but extremely effective: the device is essentially a small, localized electric pulse emitter attached alongside longline lure bait. As fishers draw their many lines through the ocean waters, the invention shoots out an electric field that discourages sharks, rays, and similar predators who hunt primarily through electroreceptors located in their snouts, known as ampullae of Lorenzini. While unpleasant to the sharks, the charges don’t seem to bother tuna much at all.
[Related: Tiger sharks helped scientists map a vast underwater meadow in the Bahamas.]
According to the new study, two fishing boats went on a total of 11 trips off the coast of southern France last year, during which they used 22 longlines deployed with over 18,000 hooks. The resulting hauls showed 91 percent fewer sharks and 71 percent fewer rays, while tuna harvests were barely affected by the SharkGuard additions. Although each SharkGuard currently requires frequent battery recharges and a set of 2,000 costs around $20,000, researchers are currently working to improve the charge times. But when it comes to large-scale commercial tuna harvesting budgets, $20K is, well, relatively small fish.
In the near future, scaling up SharkGuard availability could have an extremely dramatic and near immediate effect on reversing an unnecessary, destructive byproduct of commercial fishing. Until then, keep an eye on those great white shark counts off US coasts—more of them is a good thing, actually.
