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A Revised Operating Model for Sablefish in British Columbia in 2022

Regional Peer Review – Pacific Region

November 15-16, 2022
Virtual Meeting

Chairperson: Steven Schut

Context

Management of Sablefish (Anoplopoma fimbria) in Pacific Region is guided by a Management Strategy Evaluation (MSE) process. The MSE process uses operating models (OMs) to generate simulated data that represent alternative hypotheses for uncertain stock and fishery dynamics. The performance of candidate fishery management procedures (MPs) against each alternative OM scenario is evaluated against measurable objectives that represent conservation and socio-economic goals. Annual total allowable catches (TACs) have been set using simulation-tested MPs since 2011 (Cox et al. 2019, DFO 2020).

Sablefish OMs are revised at 3-to-5-year intervals, at which times status relative to biomass and fishing mortality reference points is characterized. Current and future performance demands for the MSE simulations require migrating the Sablefish OM and MP to a new software framework for 2022 and beyond. Thus, a comparison of updated OM and MP results to those obtained using the previous software (DFO 2020) is needed. Given updated estimates of Sablefish stock status and productivity, additional simulation-evaluation is required to determine whether the current MP, or versions that reflect current OM characteristics, can meet constraints imposed by conservation objectives.

Fisheries and Oceans Canada (DFO) Fisheries Management has requested that Science Branch provide a revised Sablefish OM for 2022 that includes updated stock and fishery monitoring data, any new hypotheses about Sablefish stock and fishery dynamics, and estimates of key management parameters. Sablefish have recently been prescribed as a major fish stock in Regulations under Canada’s revised Fisheries Act, making them subject to the Fish Stock provisions. Under the Fish Stock provisions, there is a legal requirement to maintain major fish stocks at levels necessary to promote sustainability, and to develop and implement rebuilding plans for stocks that have declined below their Limit Reference Points.

DFO is developing a national framework for ecosystem approaches to fisheries management through a recently established ‘National Working Group on Ecosystem Approaches to Fisheries Management’. The framework includes considering the integration of environmental variables (EVs) into stock assessments and fisheries science advice. In addition, the revised Fisheries Act states that the Minister shall consider the biology of the fish and the environmental conditions affecting the stock when implementing management measures. Consequently, a summary and analysis of links between Sablefish population dynamics and EVs is also requested to identify those relevant to BC Sablefish. Analyses will be data-based and guided by known, or presumed, mechanistic linkages between important Sablefish life history processes (e.g., recruitment and growth dynamics) and the ecosystem (e.g., ocean temperature). Modelled analyses that consider the possible effects of linkages between Sablefish population dynamics and EVs on harvest advice for BC Sablefish are out of scope for this review.

The assessment, and advice arising from this Canadian Science Advisory Secretariat (CSAS) Regional Peer Review (RPR), will be used to inform fisheries managers on stock status and the performance of Sablefish MPs that are used to provide harvest advice relative to established objectives for the Sablefish fishery (DFO 2020). In addition, this work will meet Fisheries Act legal obligations and support ongoing implementation of DFO’s Fishery Decision-Making Framework Incorporating the Precautionary Approach (DFO 2009) for Sablefish.

Objectives

The following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below.

Cox, S.P., S. Johnson, K. Holt, L. Lacko, A.R., Kronlund. A Revised Operating Model for Sablefish in British Columbia. 2022. CSAP Working Paper 2021GRF03.

The specific objectives of this RPR are to:

  1. Review a revised OM for Sablefish, considering:
    • Estimates of catch from all sources including landings and discards,
    • Indices used in the assessment (e.g., indices of relative or absolute abundance, recruitment, state surveys, age-length data, etc.),
    • Estimates of selectivity, annual fishing mortality, recruitment, stock biomass (both total and spawning stock), and retrospective analyses to examine model fit, and
    • Estimates of fishery reference points.
  2. Compare estimates of key model parameters and their statistical properties between the previous OM implementation and revised 2022 OM implementation.
  3. Review alternative OM hypotheses, considering sensitivity of model estimates to major axes of uncertainty that represent plausible scenarios of Sablefish population and fishery dynamics.
  4. Compare the performance of
    • the revised Sablefish MP to the previous MP implementation (DFO 2020).
    • the current Sablefish MP with alternative versions tuned to updated estimates of productivity and other key management parameters.
  5. Characterize the status of the BC Sablefish stock relative to limit and target reference points.
  6. Identify EVs based on previously published studies that may affect BC Sablefish population dynamics, present data-based explorations of links between EVs and BC Sablefish population dynamics, make recommendations about future research directions, and assess the utility of incorporating hypotheses that consider environmentally-driven change into the Sablefish MSE process.

Expected Publications

Expected Participation

References

Notice

Participation to CSAS peer review meetings is by invitation only.

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