Effect of trap soak times on risk of bycatch from offshore lobster Homarus americanus fishing operations in southwest Nova Scotia, Canada

The Canadian lobster Homarus americanus industry faces the challenge of minimizing bycatch (discarded lobster and non-target species) while optimizing catch rates in a quota-managed fishery. This study assessed the effect of varying soak times (2-14 d) on trap catches off the southwest coast of Nova Scotia. In a 1 yr, controlled, industry-led trial, the most comprehensive study of bycatch in the Canadian lobster industry, soak times were representative of commercial operations, and electronic monitoring provided independently validated data. Employing mixed logistic regressions, a significant correlation was found between extended soak times and increased risk of capturing cusk Brosme brosme and unidentified bycatch species (not specifically monitored), while no significant associations were observed for white hake Urophycis tenuis , Jonah crab Cancer borealis , Atlantic cod Gadus morhua , and rock crab Cancer irroratus . The overall impact of soak times on estimated bycatch weights for cusk and unidentified species was minor compared to more influential factors such as fishing area, depth, and temporal trends. Reducing soak times may decrease cusk and unidentified bycatch but would lead to a substantial reduction in landed lobster, requiring increased fishing efforts. Historical evidence, from regular independent at-sea observer coverage and government analysis, emphasizes that fleet rationalization and footprint concentration through trap reduction exerted a larger impact on bycatch rates than the observed changes from soak time alterations in the study. Acknowledging such historical insights will be helpful for planning strategies for mitigating bycatch in lobster trap fisheries taking place in similar environmental and operational conditions.