Globally, an estimated 9.1 million tonnes of fish are discarded each year, representing over 10% of the total global catch. Around 50% of these discards originate from bottom trawling operations. Discarding is a widespread phenomenon, widely recognised by fishers, the scientific community, and the public as a threat to food security, sustainable fisheries, and the responsible use of natural resources.
The use of light in fishing gear is an emerging area of interest, with varying wavelengths shown to lead to different responses from species, either attracting fish toward escape panels, improving their ability to detect them, or repelling fish from certain areas. Such LED applications and devices like Fishtek Marine’s NetLight have helped some fisheries overcome ‘choke’ species quotas and reduce bycatch.
A notable case study is the Oregon pink shrimp fishery, which now mandates the use of green LEDs on trawl footropes. These lights have been shown to reduce bycatch of eulachon (a type of smelt) by up to 90%, a key factor in the fishery’s Marine Stewardship Council (MSC) certification.
To further this, research in another shrimp trawl fisher in the USA reduced bycatch of slender sole and small flatfishes by 69%. It is believed that lights help the passage of fish through bycatch reduction devices. A study in the UK using an otter trawl fitted with a square mesh panel and LEDs found that unwanted bycatch of whiting and haddock was reduced by 86% and 58% respectively.
Research from a trawl fishery in the Isle of Man, UK, showed a 47% reduction in bycatch of haddock and 25% reduction in other flat fish species. Similar trials in the west coast of USA showed a 90% reduction in eulachon (a type of smelt) in a shrimp trawl.
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Paper |
Location | Product/model used | Effect | Species | Gear Type |
|
Artificial light improves escapement of fish from a trawl net. (Southworth et al., 2020) |
Isle of Man, UK | Light – constant white | 47% bycatch reduction
25% bycatch reduction |
Haddock (Melanogrammus aeglefinus)
Various flatfish spp. |
Trawl |
| Oregon, USA | Light – constant green |
90% bycatch reduction |
Eulachon (Thaleichthys pacificus) |
Shrimp trawl |
|
| Use of artificial illumination to reduce Pacific halibut bycatch in a U.S. West Coast groundfish Bottom trawl. (Lomeli et al., 2021) | Oregon, USA | Light – constant green | 58.7% bycatch reduction | Pacific halibut (Hippoglossus stenolepis) |
Trawl |