Application of the management procedure framework for Outside Quillback Rockfsh (Sebastes maliger) in British Columbia in 2021

Abstract

The purpose of this project is to provide scientifc advice to support management of Outside Quillback Rockfsh (Sebastes maliger). The stock is expected to be prescribed as a major fsh stock, at which time its sustainable management will be legislated under the Fish Stocks Provisions of the Fisheries Act. This analysis applied the Management Procedure (MP) Framework, recently developed for British Columbia (BC) groundfshes, to evaluate the performance of index-based and constant catch MPs, with respect to meeting policy and fshery objectives. To account for uncertainty in underlying population dynamics and data sources, we developed fve alternative operating model (OM) scenarios, which differed with respect to specifc model and data assumptions. Operating models were conditioned on historical catches, indices of abundance, and age composition. Three reference OMs varied on either the assumption of the natural mortality value or historical recreational catch for Outside Quillback Rockfsh. Two additional robustness OMs were developed, with evaluating a lower stock-recruit steepness value, and another that modeled lower than average recruitment in the projection. The reference OMs indicated the stock was above the limit reference point (LRP) of 0.4 BMSY with very high probability in 2021. Three fxed-catch MPs and eight index-based MPs that adjust the catch based on the recent trend in the index of abundance from the outside hard-bottom longline (HBLL) survey were tested in the closed-loop simulations. In the reference set, almost all MPs, except for the fxed catch at 125 percent of recent catch, passed the proposed satisfcing criteria with the stock: (1) exceeding the LRP with at least 75% probability, (2) exceeding the upper stock reference (USR) of 0.8 BMSY with at least 50% probability, and (3) less than the removal reference of F MSY with at least 50% probability, during the projections of two generations (54 years) duration. All index-based MPs also met the satisfcing criteria in the two robustness operating models. Visualizations present trade-offs in tabular and graphical formats to support the process of selecting the fnal MP. Among satisfced MPs, there is a trade-off between biomass and fshery catch levels after two generations. We propose operating models to be identifed in the reference set when used to identify stock status. We also provide future research recommendations regarding commercial fshery biological sampling and Food, Social, and Ceremonial (FSC) catch. We make recommendations to use the HBLL index of abundance to identify triggers for future re assessmen