Sharks have existed for upwards of 420 million years, but today more than a quarter of all known shark species face possible extinction. One of the biggest threats to their existence is bycatch, which happens when fishing vessels haul in marine life other than what they’re targeting. Scientists are looking into ways to better prevent this, and the most recent research into shark bycatch reduction focuses on their sensitivity to electromagnetic fields.
Lab and field experiments have shown that magnets and electropositive metals can be used to repel sharks. By introducing these materials to fishing hooks, sharks can be kept at a safe distance without deterring the fish species that are meant to be caught.
For some shark species, this technology significantly cut back the rate of bycatch. Sandbar sharks saw a bycatch reduction of more than two-thirds, and spiny dogfish took longer when approaching the bait. But for the blue shark species, this seemed to have the opposite effect. The magnets and electropositive metals sometimes increased the number of blue sharks caught, leading some fishers to doubt the efficacy of the specialized fishing hooks, which they nicknamed “mako magnets.”
This is just one of several potential issues that need to be tackled before the technology is ready for commercial fishing boats. There’s also the financial and logistical hurdles to consider; rare earth metals are expensive, and they degrade quickly in saltwater. Even when devices do cheaply and effectively reduce bycatch, they have still been known to face fierce opposition from fishers. Still, the new research is a step in the right direction, and could potentially lead to more solutions that exploit the unique biology of sharks for their own benefit.