The efficacy of illumination to reduce bycatch of eulachon and groundfishes before trawl capture in the eastern North Pacific ocean shrimp fishery

Abstract

This study examined the extent that eulachon (Thaleichthys pacificus) and groundfishes escape trawl entrainment in response to artificial illumination along an ocean shrimp (Pandalus jordani) trawl fishing line. Using a double-rigged trawler, we compared the catch efficiencies for ocean shrimp, eulachon, and groundfishes between an unilluminated trawl and a trawl illuminated with five green LEDs along its fishing line. Results showed a significant reduction in the bycatch of eulachon and yellowtail rockfish (Sebastes flavidus) in the presence of illumination. As eulachon are a species listed in the Endangered Species Act, this finding provides valuable information for fishery managers implementing recovery plans and evaluating potential fishery impacts on their recovery and conservation. For other rockfishes (Sebastes spp.) and flatfishes, however, we did not see the same effect as the illuminated trawl caught similarly or significantly more fishes than did the unilluminated trawl. Prior to this research, the extent that eulachon and groundfishes escape trawl capture in response to illumination along an ocean shrimp trawl fishing line was unclear. Our study has provided results to fill that data gap.