Terms of Reference

Evaluation of Data and Model Assumptions on the Calculation of Management Parameters using the Pacific Herring Assessment Model (ISCAM)

Regional Peer Review – Pacific Region

June 27-28, 2012
Nanaimo, BC

Chairperson: Linnea Flostrand

Context

Annually, an assessment of Pacific herring abundance and forecasts for the coming year is generated for each of the five major and two minor stocks in British Columbia, using a statistical catch–age-model.  The assessment framework integrates data sampled from the fishery and the population with analytical methods to model population dynamics and components of harvest control rule.  The annual assessment is reviewed through a Canadian Science Advisory Secretariat Regional Advisory Process (RAP) and harvest advice is provided to Fisheries and Oceans Canada (DFO) Fisheries Management each fall to inform the development of the Integrated Fisheries Management Plan (IFMP, DFO 2011a).

Refinements to the herring statistical catch-age model have occurred on an ongoing basis since its earliest version (Haist and Stocker 1984).  The most recent major review occurred in September 2011 (Martell et al. 2012), addressing areas of concern identified in recent RAP reviews (see DFO 2009a, DFO 2011b, DFO 2011c, DFO 2012a, DFO 2012b) and the herring stock assessment review workshop held in June 2010. The September 2011 meeting reviewed changes to: gillnet selectivity, spawn index catchability coefficient (q), and the likelihood function for age-compositions. Updated estimates of unfished biomass (B₀) were also presented, prompting changes to the stock-specific commercial fishing thresholds (effectively Limit Reference Points, LRP) calculated as 25%B₀. Structural changes to the herring assessment model were approved and the new model (iSCAM, integrated statistical catch-age model) was adopted for the provision of Science Advice in 2011 (2011 biomass estimates and forecasts for 2012).

The most recent working paper (Martell et al. 2012) also discussed compliance of the existing herring assessment framework with DFO Precautionary Approach policy “A fishery decision-making framework incorporating the Precautionary Approach” (DFO 2009b).

Proceedings from the September 2011 meeting (DFO 2012b) identify priorities for future work, primarily associated with improved understanding of the impacts of data assumptions and structural changes to the stock assessment model (iSCAM) on the calculation of current biomass (B_t) and biological reference points (B₀, MSY). Fisheries Management has requested Science advice on these future work priorities and on new approaches for the provision of advice that incorporate probability values to inform on risk based management decisions.

Objectives

Working paper to be reviewed:

Evaluation of Data and Model Assumptions on the Calculation of Management Parameters using the Pacific Herring Assessment Model (ISCAM) – CSAP Working Paper 2012-P07. Jaclyn Cleary, Vivian Haist, Steven Martell, Jake Schweigert

The objectives of this peer review process are to:

1. Improve understanding of the impacts of data assumptions and recent structural changes to the stock assessment model (iSCAM) on the calculation of current biomass (B_t) and biological reference points (B₀, B_MSY). This will be done through reviewing:
   1. Information on changes to parameterization of gillnet selectivity and the influence of these changes on estimates of B_t, B₀ and B_MSY.
   2. Sensitivity analyses for alternate prior values for q and influence of these assumptions on estimates of B_t, B₀ and B_MSY.
   3. Authors may also explore and report on:
      • Positive retrospective bias in Prince Rupert District biomass estimates.
      • Sensitivity analyses and alternate proportions in pooling of age classes (2% was applied for 2011 assessment).
      • Effects of fitting the model to 2 separate sources of age composition data: test charter data and commercial fishery data.
      • Methods for including ‘catch’ and ‘spawning biomass’ associated with spawn-on-kelp (SOK) fishery as input data to the annual assessment.
2. Improve interpretation and selection of risk-based decision tables, with probability values and defined risks associated with different management options. This will be done through reviewing:
   1. Science advice as decision tables – discuss how decision tables capture uncertainty in science advice through probability values, moving fisheries management towards risk-based decision-making.
   2. The interpretation and utility of risk metrics proposed at September 2011 RAP (DFO 2012b, relating to probabilities of SB_t+1 < 0.25B₀;  SB_t+1 < SB_t;  U_t > 0.20)
   3. Consideration of candidate management objectives and alternate risk metrics
   4. Outcomes based on existing herring decision rules (using recruitment categories of poor, average, good) with those arising from decision tables.

Expected publications

• CSAS Proceedings (1)
• CSAS Research Document (1)

Participation

• DFO Science Branch
• DFO Fisheries Management Branch
• Province of B.C.
• Commercial and recreational fishing interests
• First Nations organizations
• Non-government organizations
• Academia

References Cited and Additional Information

Cleary, J.S., J.F. Schweigert, and V. Haist. 2010. Stock assessment and management advice for the British Columbia herring fishery: 2009 assessment and 2010 forecasts. DFO. Can. Sci. Advis. Sec. Res. Doc. 2009/079. vii + 81 p.

DFO. 2009a. Proceedings of the Pacific Scientific Advice Review Committee (PSARC) Pelagic Subcommittee Meeting: Stock assessment and management advice for BC herring fishery, 2009 assessment and 2010 forecasts and herring multi-stock analysis; September 2, 2009. DFO. Can. Sci. Advis. Sec. Proceed. Ser. 2009/037.

DFO. 2009b. A fishery decision-making framework incorporating the Precautionary Approach.

DFO. 2011a. Pacific Region Integrated Fisheries Management Plan, Pacific herring, November 7, 2011 to November 6, 2012. Fisheries and Oceans Canada.

DFO. 2011b. Stock Assessment Report on Pacific Herring in British Columbia in 2010. DFO. Can. Sci. Advis. Sec. Sci. Advis. Rep. 2010/064.

DFO. 2011c. Stock Assessment Report on Pacific Herring in British Columbia in 2011. DFO. Can. Sci. Advis. Sec. Sci. Advis. Rep. 2011/061.

DFO. 2012a. Pelagics Standing Committee reviews of: Stock assessment and management advice for the British Columbia herring stocks, 2010 assessment and 2011 forecasts, and Pacific herring biological sampling program design; September 1-2, 2010. DFO. Can. Sci. Advis. Sec. Proceed. Ser. 2011/058.

DFO. 2012b. A review of the Pacific herring assessment framework and stock assessment and management advice for Pacific herring 2011 status and 2012 forecasts, September 7-9, 2011. DFO. Can. Sci. Advis. Sec. Proceed. Ser. 2011/062.

Haist, V., and M. Stocker. 1984. Stock assessment for British Columbia herring in 1983 and forecasts of the potential catch in 1984. Can. MS Rep. Fish. Aquat. Sci. 1751: 50p.

Martell, S.J., J. Schweigert, J. Cleary and V. Haist. In press. Moving towards the sustainable fisheries framework for Pacific herring: data, models, and alternative assumptions. Stock Assessment and Management Advice for the British Columbia Pacific Herring Stocks: 2011 Assessment and 2012 Forecasts. DFO. Can. Sci. Advis. Sec. Res. Doc. 2011/136.