Sharks steer clear of glowing fishing nets

Fishing nets lit by glowing green LED lights may prevent sea turtles, sharks and rays, including threatened species, from being tangled accidentally.

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

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

Overall bycatch was down 63% and there was a 95% drop in sharks, skates and rays caught in the glowing nets.

But why the LED lights work so well on 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 fall in catches of targeted fish.

One big challenge is figuring out how to make illuminated nets more cost effective. Batteries for the LED lights are expensive and need continuing operational costs, which may be hard on fishermen in developing countries.

So Senko is 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 [bycatch] gets thrown back into the water, and so it’s wasted,” Osmond said. “Bycatch is driving a lot of species toward extinction.”

Reuters