Research Document 2024/028
Application of the Management Procedure Framework for Outside Quillback Rockfish (Sebastes maliger) in British Columbia in 2021
By Huynh, Q.C., Siegle, M.R., and Haggarty, D.R.
Abstract
The purpose of this project is to provide scientific advice to support management of Outside Quillback Rockfish (Sebastes maliger). The stock is expected to be prescribed as a major fish 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) groundfishes, to evaluate the performance of index-based and constant catch MPs, with respect to meeting policy and fishery objectives.
To account for uncertainty in underlying population dynamics and data sources, we developed five alternative operating model (OM) scenarios, which differed with respect to specific 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 Rockfish. 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 fixed-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 fixed catch at 125 percent of recent catch, passed the proposed satisficing 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 FMSY with at least 50% probability, during the projections of two generations (54 years) duration. All index-based MPs also met the satisficing criteria in the two robustness operating models.
Visualizations present trade-offs in tabular and graphical formats to support the process of selecting the final MP. Among satisficed MPs, there is a trade-off between biomass and fishery catch levels after two generations. We propose operating models to be identified in the reference set when used to identify stock status. We also provide future research recommendations regarding commercial fishery biological sampling and Food, Social, and Ceremonial (FSC) catch. We make recommendations to use the HBLL index of abundance to identify triggers for future reassessment.
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