Quasi-Stationary Atlantic Cod Bycatch Estimation in the Maine American Lobster Homarus americanus Trap Fishery

The Atlantic Cod Gadus morhua population in the Gulf of Maine (GOM) is currently near historically low levels of abundance. Reliable estimates of incidental Atlantic Cod bycatch from Maine's American lobster Homarus americanus fishery, which are unavailable and not included in the current stock assessment, are potentially critical for understanding complete catch dynamics and are thus essential for rebuilding the stock. Available fishery-dependent data cannot be used directly in estimating Atlantic Cod bycatch because of nonrandom spatial and temporal sampling efforts. We developed a standardized framework for estimating Atlantic Cod bycatch in Maine's inshore lobster fishery for the years 2006–2013. We employed environmental covariates in a bootstrapped generalized additive model framework to standardize monthly zonal Atlantic Cod bycatch per unit effort (BCPUE) and lobster CPUE. Bootstrapped distributions of standardized CPUE and BCPUE were combined with landings data to estimate spatiotemporally explicit confidence intervals of Atlantic Cod discards in the Maine lobster fishery. Modeling results remained consistent throughout the study years, suggesting robustness in our approach. The estimates of Atlantic Cod discards in the lobster fishery improve the understanding of the total GOM Atlantic Cod bycatch and help to address current stock assessment deficiencies.