Lighted fishing nets may save sharks, sea turtles from accidental entrapment

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Fishing nets that glow green with LED lights may prevent sea turtles, sharks and rays, including many threatened species, from becoming accidentally entangled, a study found.

Experts say bycatch, the unwanted fish and marine life caught by commercial fishing, accounts for 40 per cent - or 38 million tons - of the world's global catch.

The study publish in the journal Current Biology compared the performance of regular gill nets - vertical panels of netting that hang below the surface - to illuminated ones off the coast of Baja California, Mexico.

Overall bycatch was down by 63 per cent and there was a 95 per cent reduction in sharks, skates and rays caught in the glowing nets.

But why the LED lights work so well on some species like sharks remains a mystery.

"The honest answer is: We don't know," said Jesse Senko, a marine conservation biologist at Arizona State University, who conducted the study. "We assume that it's probably some type of warning or deterrent for the animal."

Importantly, the study found no significant reduction in the amount of targeted fish caught.

Now, one of the biggest challenges is figuring out how to make the illuminated nets more cost-effective.

The batteries for the LED lights are pricey and require ongoing operational costs, which may be especially hard on fishermen in developing countries.

Senko is, therefore, experimenting with solar-powered lights, which he said can last for a week with only 30 minutes of sunlight.

Michael Osmond, a senior programme manager for the World Wildlife Fund's Oceans Team, who was not involved in the study, said the technology is promising - and badly needed.

"Most of (bycatch) gets thrown back into the water, and so it's wasted," Osmond added. "Bycatch is driving a lot of species toward extinction."