The effects of LED handline attachments on Atlantic cod (Gadus morhua) catch efficacy and bycatch

Abstract

Catch efficacy and bycatch are critical factors that determine the sustainability, practicality, and profitability of fishing gears. Inshore Atlantic cod (Gadus morhua) fisheries commonly use gillnets, cod-pots, longlines and handlines. Owing to their efficiency, selectiveness, and low effort, gillnets are the most widely used gear. Gillnets however are prone to bycatch and low-quality catch. Handlines benefit from low capital investment, live high-quality fish, low bycatch, and low carbon footprint. Enhancements to handlines that could increase catch rate or size of catch would be considered beneficial and could promote uptake by harvesters using other gear types. Previous pilot research has shown that LED handline attachments that target the visual sensitivity of cod increased the catch rate of Atlantic cod. The present study builds upon this finding, incorporating three participating commercial crews and vessels. We found no significant effect of LED handline modifications on catch efficacy for Atlantic cod or bycatch. The bycatch of Atlantic wolffish (Anarhichas lupus) in our study was found to decrease with the use of green LEDs, but the data precludes complex statistical analysis. We discuss how these findings are relevant to small-scale fishers and provide an empirical reference regarding the use of such devices in the commercial fishery.