Impact of Codend Mesh Sizes on Selectivity and Retention of Acadian Redfish Sebastes Fasciatus in the Gulf of Maine Trawl Fishery

We conducted a codend selectivity study in the US Gulf of Maine as part of an effort to reestablish a sustainable trawl fishery for Acadian redfish (Sebastes fasciatus). Fifty-six tows were completed in March and April 2013 using a commercial fishing vessel and a trouser trawl, testing three diamond mesh codends (114 mm, 140 mm, 165 mm) against a 63 mm codend as the non-selective control codend. Based on the results for individual tows, a predictive model for the effect of codend mesh size on mean L50 and mean SR was established. From this model, mean L50 and SR, and confidence intervals were estimated for all three tested codends, incorporating both within and between haul variability by using the selectivity software SELNET. All measures of model validity were positive. Simulation of fishing with the three tested codends on the observed population indicated that substantial escape of redfish through codend meshes occurs (48-94%), suggesting that investigation of escape of redfish is warranted to support a sustainable fishery.  These results are intended to guide the managers and fishermen on size retention of redfish and appropriate codend mesh size for the revitalized fishery.