Many millions of sharks end their days as bycatch every year, when tuna and other species are fished in open seas around the world. It happens because of longline fishing, a technique that can be a bit reminiscent of angling and is used by the commercial fishing industry: behind a boat hang lines several kilometers long, to which thousands of hooks are attached, which are lowered into the depths of the sea. The company Fishtek Marine has tried to find a solution to the problem of line fishing bycatch, by developing further on an earlier technology that has proven to be effective in scaring away sharks to protect divers and surfers. This has led to the development of SharkGuard, small electrical units that are attached to the fishing lines, and which have been shown to be able to reduce the bycatch of blue sharks and so-called pelagic skates (skates that do not live on the seabed) by 91 per cent and 71 per cent respectively. Researchers at the University of Exeter in England have been involved in testing the technology, the results of which have been peer-reviewed and published in the scientific journal “Current Biology”. The effect of the technology is not just isolated to blue sharks and skates, according to marine biologist Rob Enever, who is head of research for FishTek Marine. – These (blue sharks and pelagic skates) were the only species that were present during our experiments. But the effect of SharkGuard is not limited to just these species, he says. We had a chat – via e-mail – with Rob Enever in connection with the promising results to learn more about how the technology actually works. Because there is a lot at stake. Since 1970, the world’s population of sea sharks and skates has decreased by 71 percent due to pressure from the fishing industry, research shows. Q&A with Fishtek Marine Hi Rob, what is SharkGuard – and why is it interesting? “SharkGuard is a small electronic unit that emits a powerful electric field around the hooks on a fishing line. Sharks have – in contrast to fish – electroreceptors called “ampullae of Lorenzi”, in other words sensory organs that are capable of perceiving electric fields. These specialized organs are partly used to identify prey that create small electric fields, and partly for navigation using the Earth’s magnetic field. If these sensory organs are overstimulated, the sharks are frightened by the electric fields and swim away.” How did you come up with the idea? “The use of electric fields to scare away sharks is not new. Commercial companies equip both divers and surfers with equipment designed for this very purpose. The biggest challenge for us was to make the technology smaller in size, so that it could be used in the fishing industry on a larger scale.” How big a game-changer do you think the technology can be when it comes to avoiding bycatch in the future? “Giant. It (SharkGuard) really has the potential to reverse the decline of pelagic shark species (i.e. species that do not live on the seabed) caused by longline fishing.” Does this SharkGuard technology have a catch? “We don’t see many disadvantages right now. At the moment, our SharkGuard unit uses replaceable batteries. We know that this is useless for the fishing industry, but we operate and develop the commercial prototype (MKV), which can now be uploaded automatically. SharkGuard is ready for commercial use in 2023 or 2024.” The technology cannot stand alone The Guardian has asked other experts what they think of the SharkGuard technology. According to Phil Doherty, a marine biologist with expertise in nature conservation, there is no doubt that the technology works on blue sharks and pelagic skates when you look at the research results – but he says that more studies are needed to see if the technology can be used to avoid bycatch of other species . Nevertheless, it is still not said that this cannot be done. Ali Hood from SharkTrust, a charity for the protection of sharks and skates, welcomes technologies such as SharkGuard, but they cannot stand alone: - Setting limits on, or even banning, the capture of sharks and skates (…) is the first step towards seeing fish stocks grow again, Hood told The Guardian.
ttn-70
From this fishing boat in the Mediterranean, researchers have tested a case that reduces bycatch of sharks by up to 91 percent.
