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Global shark populations are in a dramatic decline due to industrial fishing and the shark fin trade.

Many thousands more are accidently hooked on fishing lines.

But a group of conservationists are working hard to find solutions to prevent sharks from getting caught by accident.

They've created a device that emits tiny electrical pulses known as SharkGuard. And the research suggests it could be really useful in protecting them.

SharkGuard - how does it work?

The device is powered by a small battery and works by targeting a shark's sensitive nose and mouth, which is packed full of electrical sensors.

They use these in-built sensory organs to target prey so when the clever shark-tech is emitting these electrical pulses, it overstimulates the sharks senses.

So rather than swim towards it, the research indicates the sharks are in fact swimming away from the baited hooks instead.

The researchers found that the baited lines fitted with the device reduced accidental catching of blue sharks by 91% and stingrays by 71% which is encouraging for the team which developed it.

Pete Kibel, co-founder and director of Fishtek Marine, said "When SharkGuard is used, sharks do not take the bait and do not get caught on the hooks, and that gives us a huge sense of hope."

Dr Phil Doherty, of the Centre for Ecology and Conservation at the University of Exeter's Penryn Campus in Cornwall, said these tests showed the device was "remarkably effective".

But decades of overfishing has caused many shark populations to shrink.

"There is an urgent need to reduce bycatch (when sharks are caught instead of other fish by accident), which not only kills millions of sharks and rays each year but also costs fishers time and money," said Dr Doherty.

"Our study suggests SharkGuard is remarkably effective at keeping blue sharks and pelagic stingrays off fishing hooks."

'A global gamer-changer'

While these are promising results, researchers said the total number caught in the test period - on lines with and without SharkGuard - was low and so further trials are needed.

The device is also being modified to be smaller and self-charge, so if it is used on a wider industrial scale in the future it can be used with every fishing haul.

Professor Brendan Godley, who leads the Exeter Marine research group, said the device had "the potential to be a global game-changer for the sustainability of longline fishing".

Since 1970, the number of sharks worldwide has fallen by 71 percent.

In the Journal of Animal Ecology, the scientists warned that, without sharks, the world's oceans will become far less resilient to extreme climate events.