Posted on 02/12/2022 2:31:24 PM PST by nickcarraway
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."
Probably reduces catch of wanted fish by the same amount.
Can’t they just tear big holes in their nets and accomplish the same numbers? At least they wouldn’t have to buy the new, expensive nets.
The chinese don’t care. They want EVERYTHING in the nets.
Or shows the sharks where the easy meals are...
The solution in the Puget Sound and Juan de Fuca salmon fisheries was to make the top 3 feet of 10 inch meshes.
Naturally the salmon running in the top 10 feet of the water column just went through the mesh significantly reducing the catch - particularly when red singing jelly fish were thick forcing the salmon towards the surface.
The combination of very large mesh and small 5-6” mesh made the nets a nightmare to get on and off gillnet reels.
In the fall, Seattle’s poorly treated sewage discharges causes horrendous algae blooms which cling to the nets forcing the fisherman to install pressure washing as the net comes in.
This still creates a sticky mess with the large mesh prone to tuck under the cork and lead lines causing backlashes which stop the setting of the net, tearing holes in it.
Or shows the sharks where the easy meals are...
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More likely seals and sea lions.
“Importantly, the study found no significant reduction in the amount of targeted fish caught.”
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