Terms of Reference

Stock Assessment and Management Advice for BC Pacific Herring: 2016 Status and 2017 Forecast

Regional Science Response Process – Pacific Region

September 2016
Nanaimo, BC

Chairperson: Jaclyn Cleary

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. Martell et al. (2012) introduced estimated cutoff and estimated q (catchability) to the management procedure (termed the “current MP”). 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 MP (q =1 and fixed cutoffs), as well as the potential implications of the model for fisheries management (e.g., higher estimates of spawning abundance in some areas, potential to open fisheries at lower biomass levels than under the historical MP).

Fisheries and Oceans Canada (DFO) Pacific Fisheries Management Branch has requested that DFO Pacific Science Branch assess the status of BC herring stocks in 2016, and provide projections of potential herring abundance in 2017 and the consequences of a range of potential harvests to support the development of the 2016/17 Integrated Fisheries Management Plan (IFMP).

A statistical catch-age model (ISCAM) will be used to estimate the 2016 spawning stock status and provide a forecast for 2017 in the form of a stock assessment update. Stock status and trends, as well as projected biomass for 2017 (including uncertainty) will be presented in the form of decision tables. The 2016 stock assessment will include biomass estimates and decision tables resulting from application of two modelling approaches: assessment modeling 1 (AM1) – estimate q , estimate cutoffs, and assessment modeling 2 (AM2) – fixed q , fixed cutoffs. The Science Response will also include a description of the history and limitations of each modelling approach. The assessment, forecast and advice arising from CSAS Science Response will be used to support the development of the herring IFMP for 2017.

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.
Present trends in herring biomass, depletion, and recruitment for each major and minor stocks.
Evaluate the consequences (including potential risk of exceeding harvest rates prescribed by both modelling approaches) of different total allowable catch levels for 2017 against probabilistic metrics to accommodate uncertainty in the advice.