Electric pulses could get sharks off the hook of tuna fishing lines

SHARKS can be saved from being accidentally caught on tuna fishing lines by electrical pulses, scientists have found.

More than 100 million sharks and rays die every year as fishing bycatch, with 20 million perishing after being snagged on long-line fishing hooks used to catch bluefin tuna.

Eco-minded engineers at Fishtek Marine in Devon created the “Sharkguard” that is 12cm long and has a 60 hour battery life and clips on to standard hooks. The device emits electrical pulses that discourage sharks but can not be picked up by tuna.

Eleven fishing trips on French waters revealed that using the gadget reduced the number of blue sharks accidentally caught by tuna fishing by 91 per cent.

For every 1,000 hooks, there were 6.1 sharks ensnared in the normal conditions but this number fell to 0.5 per 1,000 when Sharkguard was operating.

Sharks have electroreceptors that enable them to detect small electric fields and they use this to hunt, a rare trait that few other fish possess.

Dr Rob Enever, head of science and uptake at Fishtek Marine, said: “They also use it for migration with the Earth’s magnetic fields.

“There’s not many animals that have these organs and if you overstimulate them then you can get them to turn tail and swim away.

“It’s like if you put your finger on an electric fence, it’s not going to kill you but you don’t want to hang around.”

The prototype created by the British company is battery powered, which the developers acknowledge is not practical if it was to be adopted in industry.

The company expects 2,000 guards to cost around $20,000 (£16,000).