A simple technique to illuminate the exits in trawling nets could cut accidental bycatch by half a recent study has shown. The study, published in the Journal of the Marine Biological Association of the United Kingdom, found that attaching LED lights to the larger holes in a net allows non-target species to escape, reducing the number that are killed. The research was conducted by a team from Bangor University, led by marine ecologist, Dr Lucy Southworth.
Bycatch, the capture of non-target species, can significantly damage the populations of these species, many of which are vulnerable or endangered, and drastically reduce their numbers. Similarly, seabirds and marine mammals can become victims of accidental bycatch through entanglement in fishing nets, which often kills them in the process.
But it's not just the environment that is negatively affected by bycatch. There is also a significant cost to the fishermen. Under EU law, fishermen are required to bring almost everything they catch to shore, including that which is not a part of their quota. If too many non-target fish are caught, the entire fishery may be closed to allow stocks to recover. As a result, even fishermen doing their best to comply with the rules can cause unintended damage and end up risking their livelihoods.
The new study, conducted between June and August 2017, is a clever inversion of an old fishing technique: shining a light on the water to attract fish into the net. The team set out to test the effect of lights in reducing the number of haddock and flatfish that were accidentally caught in a queen scallop fishery off the Isle of Man.
They found that, while the devices that are currently used to reduce bycatch were effective in shallower waters of around 29 to 40 m, they had little to no effect in deeper waters of around 45 to 95 m. This is likely due to the lack of light and, therefore, visibility. Once LED lights were attached to the net exits in these deeper waters, haddock bycatch was reduced by 47% and flatfish bycatch by 25%.
The team even found of evidence of sharks escaping the lit nets, which could be a topic for future research. LED lights could also potentially reduce the number of whales, dolphins, and porpoises entangled in nets each year as they alert the animals to the presence of these nets and give them the chance to avoid the hazard.
Dr Southworth and her colleagues believe that this could be a popular solution to the current issues with bycatch. Not only are LED lights fairly cheap, they are easy to apply to the nets and can be easily adjusted for different environments. Though there is still a long way to go before the issue of bycatch is solved, it's certainly refreshing when simple answers can be found for complicated problems.
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