Research Document - 2011/115

Stock Assessment and Management Advice for the British Columbia Herring Stocks: 2010 Assessment and 2011 Forecasts

By J.S. Cleary and J.F. Schweigert

Abstract

Herring stock abundance in British Columbia (B.C.) waters are assessed for 2010 and forecasts were made for 2011 using the herring catch-age model (HCAMv2), developed for the 2008 assessment (and revised in 2009). B.C. herring stocks are managed as five major and two minor stock areas. Accordingly, catch and survey information is collected independently for each of these seven areas and science advice is provided on the same scale. All available biological data on spawn deposition and age and size composition of the spawning stocks, as well as commercial harvest data, were used to determine current abundance levels. Herring abundance has remained relatively stable over the past few years, with no substantial changes in 2010. The total estimated pre-fishery biomass for the major assessment regions for 2010 is 84,656 metric tonnes (t), broken down as follows: Haida Gwaii (QCI 2E) – 6,046 t, Prince Rupert District (PRD) – 19,039 t, Central Coast (CC) – 7,974 t, Strait of Georgia (SOG) – 48,262 t, and west coast of Vancouver Island (WCVI) – 3,335 t . Pre-fishery biomass estimates for 2009 and 2008 are 103,470 t and 95,076 t, respectively. Recruitment of the 2007 year class in 2010 was poor for HG, CC, SOG and WCVI, while recruitment in PRD was average. Pre-fishery biomass for the minor stock areas for 2010 and recruitment of the 2007 year class in 2010 were estimated as 7,593 t with good recruitment for Area 2W and 998 t with poor recruitment for Area 27.

Stock projections for 2011 indicate reduced abundance and poor recruitment in three major stock areas. Implementation of the herring harvest control rule (HCR) advises the following stocks will not support a commercial harvest: HG, WCVI, and CC. Spawning stock biomass for two of the five major stock areas is forecast to be above the biomass cutoff level for 2011. Based on a 20% harvest rate and application of the recruitment forecasting rules, the estimated maximum available harvest of B.C. herring for 2011 is 3,834 t for the PRD stock (assuming average recruitment) and 13,777 t for the SOG (assuming good recruitment). The HCR for the minor stock areas assumes average recruitment, in developing the stock biomass forecast, and recommends a 10% harvest rate. Following application of these rules, the recommended maximum available harvest for the minor stocks in 2011 is: 253 t in Area 2W (based on the 2010 spawn index) and 94 t in Area 27.

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