One of the reasons, endangered turtles like the Olive Ridley turtles and Green turtles are dying in large numbers in the world oceans today is because they become victims of accidental by-catch during fishing. But now a new technology might prevent this from happening by using fishing gear that sport Ultraviolet light (UV) emitting diode and warn the turtles to stay away from the nets.
The advantage of using the technology according to the researchers is that the turtles will be able to detect the rays but most commercially valuable fish species can still be captured. The technology therefore is aimed to let the fisherman continue with their livelihoods, and still ensure that the rare turtles are protected.
Different Vision
In recent times, there have been many studies conducted to see how fishing gears can be made safer so as to keep the accidental catch of turtles, sharks and other marine animals away. One previous study found that green sea turtles tended to stay out of nets fitted with green light-emitting diodes (LEDs) and chemical lightsticks.
For the recent research scientists tried to compare the visual range of sea turtles and fishes and found that turtles were more sensitive to UV light than the latter. To test if this knowledge could be used to develop safer fishing nets for the turtles, the team performed separate experiments both in Mexico.
In the first experiment at Punta Abreojos in Mexico scientists fitted two nets with LEDS. While one emitted UV light, the other did not. These nets were lowered into the ocean waters, that are known turtle habitats from sunrise till sunset. The nets were checked every 90 minutes to see if any turtles had been netted.
The second experiment, conducted in a commercial fishery in Bahia de los Angeles used similar paired nets to check whether fishes were affected by the presence of UV emitting diodes with the nets.
Results
Of 332 green turtles captured during the first part of the study, only 123 (37%) were from UV-illuminated nets; the remaining 209 were captured from the nets without diodes. The results show that the simple addition of an UV emitting diode reduced the by-catch drastically.
The second experiment where fishes were observed found that unlit nets only caught 46 more target fish than those fitted with UV lights. Therefore, the number of fish of commercial value that fishermen could catch was not affected in a major way, due to the presence of the UV light diodes.
Safe Light
The study points to a medium that can be certainly researched further and adapted by fishermen to ensure that turtles are not accidentally caught while they go fishing. The researchers are still trying to find if the turtles are distracted by the UV light and avoid the nets or if the presence of the light helps them see better and therefore they bypass the nets.
The team also adds that different fishery spots may have different fishes with varied visual range and before the technology can be applied in these areas, it would be helpful to experiment in a small area first.
According to conserveturtles.org, each year, more than 250,000 sea turtles are accidentally captured, injured or killed by U.S. by fishermen . In India almost 2000 turtles die each year because of a similar fishing net entanglement.
The good news is therefore that with little modification of their fishing gears, fishermen can save rare turtles from these untimely deaths or lifelong injuries. It is a solution that will suit conservationists as well as the fishermen.
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Image via cc/Flickr by USFW Pacific and Dalla
Turtle in the Net image courtesy Blackfish.org
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