Terms of Reference

Stock Assessment and Management Advice for BC Pacific Herring: 2015 Status and 2016 Forecast

Regional Science Response Process – Pacific Region

September 2015
Nanaimo, BC

Chairperson: Marilyn Hargreaves

Context

Pacific Herring is a pelagic species inhabiting inshore and offshore waters of the North Pacific from California to the Bering Sea. Herring annually migrate between feeding and spawning areas. Pacific Herring in British Columbia are managed based as five major stock management areas: Haida Gwaii, Prince Rupert District, Central Coast, Strait of Georgia, and West Coast of Vancouver Island (WCVI), and two minor stock management areas: Haida Gwaii Area 2W and WCVI Area 27.

The assessment of current Pacific Herring abundance and forecasts has been done annually since the late-1980s, for each of the five major and two minor stocks in British Columbia, utilizing a statistical catch–age-model since 2006 (Martell et al, 2012; DFO 2013). The catch-age model is fitted to commercial catch, proportions-at-age and fishery-independent survey index to estimate biomass and recruitment and to generate 1-year forecasts of spawning biomass. Since Martell et al. (2012) introduced estimated cutoff and q elements of the assessment (the current management procedure), questions have been raised regarding their application relative to the historical management procedure (q=1 and fixed cutoffs), as well as the potential consequences of these two management procedures using simulation.

In May 2015, a closed loop-simulation tool to evaluate various management procedures and ecological hypotheses relative to a series of performance metrics was developed for Pacific Herring and reviewed and endorsed through a CSAS Regional Peer Review Process. This analytical framework has both immediate utility for this year’s stock assessment, and may have longer-term utility to inform the renewal of the management framework for BC Pacific Herring.

Fisheries and Oceans Canada (DFO) Pacific Fisheries Management Branch has requested that DFO Pacific Science Branch assess the status of BC herring stocks in 2015, and provide projections of potential herring abundance in 2016 and the consequences of a range of potential harvests to inform the development of the 2015/16 Integrated Fisheries Management Plan (IFMP).

Both the request to compare historic and current management procedures using simulation, and the request to assess BC herring stock status will be addressed separately in this assessment. The simulation tool will be used to compare standard performance metrics such as mean catch, variability in catch, and the probability of dropping below candidate limit reference points, for the historic and current management procedures. The approved catch-age model (ISCAM) will be used to estimate the 2015 spawning stock status and provide a forecast for 2016 in the form of a stock assessment update. Current stock status and trends, as well as projected biomass for 2016 (including uncertainty) will be presented in the form of decision tables. Biomass estimates and decision tables will reflect both the current (estimating q, time varying cut-offs) and historic (q=1, fixed cut-offs) management procedures. The simulation analysis and stock assessment will be presented using a Science Response.

Objectives

Guided by the DFO Fishery Decision-making Framework Incorporating the Precautionary Approach (DFO 2009) under the Sustainable Fisheries Framework, a CSAS Science Response will be developed to:

Assess the current status of Pacific Herring for each of the five major and two minor stocks using both the current and historical management procedures.
Present trends in herring biomass, depletion, and recruitment for each major and minor stocks using both the current and historical management procedures.
Evaluate the consequences (including potential risk of exceeding harvest rates prescribed by the current harvest control rules) of different total allowable catch levels for 2016 against probabilistic metrics to accommodate uncertainty in the advice (using both the current and historical management procedures).
Apply simulation analysis to compare the performance of the current (estimate q, time varying cut-offs) and the historic (q=1, fixed cut-offs) management procedures against a range of potential criteria (e.g. candidate limit reference points).