Reducing green turtle bycatch in small-scale fisheries using illuminated gillnets: the cost of saving a sea turtle
Gillnet fisheries exist throughout the oceans and have been implicated in high bycatch rates of sea turtles. In this study, we examined the effectiveness of illuminating nets with light-emitting diodes (LEDs) placed on floatlines in order to reduce sea turtle bycatch in a small-scale bottom-set gillnet fishery. In Sechura Bay, northern Peru, 114 pairs of control and illuminated nets were deployed. The predicted mean catch per unit effort (CPUE) of target species, standardized for environmental variables using generalized additive model (GAM) analysis, was similar for both control and illuminated nets. In contrast, the predicted mean CPUE of green turtles Chelonia mydas was reduced by 63.9% in illuminated nets. A total of 125 green turtles were caught in control nets, while 62 were caught in illuminated nets. This statistically significant reduction (GAM analysis, p < 0.05) in sea turtle bycatch suggests that net illumination could be an effective conservation tool. Challenges to implementing the use of LEDs include equipment costs, increased net handling times, and limited awareness among fishermen regarding the effectiveness of this technology. Cost estimates for preventing a single sea turtle catch are as low as 34 USD, while the costs to outfit the entire gillnet fishery in Sechura Bay can be as low as 9200 USD. Understanding these cost challenges emphasizes the need for institutional support from national ministries, international non-governmental organizations and the broader fisheries industry to make possible widespread implementation of net illumination as a sea turtle bycatch reduction strategy.