Simple solution, big benefits – LED lights shown to reduce eulachon bycatch
Researchers have discovered a simple but extraordinarily effective means of keeping threatened eulachon out of fishing nets trawling for pink shrimp: light up their escape route.
Scientists with the Oregon Department of Fish and Wildlife found that LED lights attached to the trawl lines illuminate the escape path under the net, allowing eulachon and other species that enter the net to find their way back out.
Early results indicate that illumination reduces the unintended catch, or bycatch, of eulachon. Of 42 tows, evaluated under a variety of conditions, the new technique demonstrated a 90.4% reduction in eulachon bycatch; while the catch of pink shrimp – the target species – was largely unaffected, reduced by less than 1%. Bycatch of other fish species, including darkblotched rockfish and slender sole, was also significantly reduced.
Left: A pink shrimp haul without the use of LED lights shows Eulachon bycatch. Right: The results of LED lights hung on the trawl lines. LEDs have significantly reduced bycatch of threatened Eulachon as well as other fish by showing where the fish can escape the net.
“Though we’re still fine tuning the method,” said Bob Hannah of the Oregon Department of Fish and Wildlife, “the use of properly placed lights really is showing a remarkable reduction in the catch of eulachon while still retaining shrimp.”
The new technique was shown to be effective when the lights were placed four feet apart across the center third of the footrope, an area near the bottom of the trawl that keeps the net open as it moves through the water. Researchers caution shrimpers to not place the lights around the rigid-grate bycatch reduction device, or BRD, as it actually decreased the effectiveness of the BRD for eulachon.
Shrimpers are encouraged to start using and testing a lighted fishing line immediately. “We need the fleet to start using these lights. But more than that, we need shrimpers to tell us about their experiences, what worked well and what didn’t, so we can find the optimal arrangement of lights for reducing bycatch,” said Hannah.
The research was funded through NOAA Fisheries’ Bycatch Reduction Engineering Program and administered by the Pacific Sates Marine Fisheries Commission. The preliminary results hold promise for conserving eulachon, which is federally protected under the Endangered Species Act.
Eulachon has long been caught in the ocean shrimp fishery. The fishery was identified by NOAA Fisheries as one of the primary threats to the species and its recovery. Collaborations like this research initiative between the Oregon Department of Fish and Wildlife, NOAA Fisheries, Pacific States Marine Fisheries Commission, and the ocean shrimp fishing industry lead to innovative solutions that support resource conservation while maintaining strong, sustainable fisheries.
To learn more about the study, please visit: http://www.dfw.state.or.us/MRP/publications/docs/shrimp_newsletter2014_midseason.pdf
To learn more about eulachon recovery efforts, please visit: http://www.westcoast.fisheries.noaa.gov/protected_species/eulachon/pacific_eulachon.html
Home page photo: Blane Bellerud