Estimation of Partial Recruitment and Yield per Recruit for an Otter Trawl Fishery for Deepwater Redfish

Abstract

Abstract The Canadian deepwater redfish (Sebastes mentella) fishery in the Atlantic ocean tends to be concentrated in a limited depth range to maximize catch rates and optimize size composition of the catches that vary with depth. Thus, the assumption of Beverton and Holt's yield-per-recruit analysis that all fish are equally subject to fishing mortality beyond a certain size seems inappropriate for this fishery. The alternative method of Thompson and Bell is more flexible but requires estimated age-specific, partial recruitment factors as an input. In this study, selectivity factors empirically determined for various bottom trawl mesh sizes and information from research vessel surveys on the composition of deepwater redfish catches in different depth zones were analysed to estimate partial recruitment factors for subsequent yield calculations. Partial recruitment factors were estimated for the commercial otter trawl fishery on deepwater redfish in Divisions 2J and 3K of the Northwest Atlantic Fisheries O...