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Application of a new modelling framework for the assessment of Pacific Herring (Clupea pallasii) major stocks and implementation in the management strategy evaluation process

Regional Peer Review - Pacific Region

June 26-28, 2023
Nanaimo, BC

Chairperson: Steven Schut

Context

Pacific Herring (Clupea pallasii) in British Columbia (BC) are currently managed in five major and two minor stock assessment regions. The major stocks included in this model review are Haida Gwaii (HG), Prince Rupert District (PRD), Central Coast (CC), Strait of Georgia (SoG), and West Coast of Vancouver Island (WCVI). Pacific Herring are an important species to First Nations, with coastal Indigenous fisheries, as well as treaty and Aboriginal commercial fisheries in specific management areas.

Fisheries and Oceans Canada (DFO) uses a Management Strategy Evaluation (MSE) process to collaborate with First Nations, non-governmental organizations and the Herring Industry Advisory Board to develop and implement sustainable harvest strategies for Pacific Herring. The use of the MSE process aligns with DFO’s “A Fishery Decision-Making Framework Incorporating the Precautionary Approach” policy (DFO 2009). The process uses an analytical framework to evaluate sustainability of harvest strategies by simulation testing alternative management procedures against operating model (OM) scenarios that represent a range of hypotheses about uncertain population and fishery dynamics. Performance of alternative management procedures (combinations of data, stock assessment model, and harvest control rule, MP) are measured against pre-agreed conservation and catch objectives for each stock area and fishery (Cox et al. 2019; DFO 2023a).

The MSE framework was first implemented in the herring advisory process in 2018 (Benson et al. 2023; DFO 2020). This framework uses a statistical catch-age model in both the MP (annual assessment of BC herring stocks) and to estimate key population parameters used in the operating models (Cleary et al. 2019; DFO 2018). Previous scientific reviews, ongoing consultation with First Nations and fishery stakeholders, and increasing survey costs indicate a need for added functionality in the assessment and operating models, including:

  1. a method for integrating data from surface and dive surveys in estimation of the survey index;

  2. inclusion of removals from the spawn-on-kelp fisheries;

  3. implementing fishing mortality in discrete time steps within a fishing season; and

  4. parameterizing depensatory natural mortality to better represent potential ecosystem impacts on herring stocks.

Fisheries and Oceans (DFO) Resource Management has requested that DFO Science update and review the model used for annual assessment of BC Pacific Herring stocks (choice of model, data, assumptions) to include elements (1) to (4) and demonstrate its utility for representing additional dynamics as operating models in the MSE analytical framework. This process will not include a stock assessment, forecast of mature stock biomass, nor harvest options for 2023 as those aspects will be covered in a subsequent Canadian Science Advisory Secretariate (CSAS) processFootnote 1.

Objectives

Guided by the DFO Sustainable Fisheries Framework, particularly the Fishery Decision-making Framework Incorporating the Precautionary Approach (DFO 2009), the following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below.

Johnson, S.D.N., Cox, S.P., Cleary, J.S., Benson, A.J, Power, S.J.H., and Rossi, S.P. Application of a new modelling framework for the assessment of Pacific Herring (Clupea pallasii) major stocks and implementation in the management strategy evaluation process. 2023. CSAP Working Paper 2019PEL01.

The specific objectives of this review are to:

  1. Present a new statistical catch-age model including simulation-estimation tests and comparisons with 2022 base model parameterizations from the previous model (Cleary et al. 2019 modifications to Martell et al. 2012).

  2. Assess suitability of the new statistical catch-age model for the five major Pacific Herring stocks for estimating trends in biomass, depletion, and recruitment for each major stock. Present retrospective evaluation, trends, and stock status in 2022 relative to the limit reference point (Kronlund et al. 2018) and the upper stock reference point based on the average productive period (DFO 2023a; DFO 2023b).

  3. Demonstrate the new statistical catch-age model as an operating model for the Pacific Herring MSE process. Identify key uncertainties related to environmental variability, natural mortality, data and assessment methods, and evaluate these in the context of precautionary approach (PA) compliant management procedures.

  4. Propose an implementation plan for the Pacific Herring MSE process, including timelines for routine MSE updates, choice of operating models to include, and exceptional circumstances that would trigger an earlier update of the MSE process than what is proposed in the implementation plan.

Expected Publications

Expected Participation

References

Notice

Participation to CSAS peer review meetings is by invitation only.

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