Research Document - 2008/011

Stock Assessment for British Columbia Herring in 2007 and Forecasts of the Potential Catch in 2008

By J. Schweigert, and V. Haist

Abstract

Herring stock abundance in British Columbia waters was assessed for 2007 and forecasts were made for 2008 using the new age structured assessment model (HCAM) for the major stock assessment regions and for the minor stocks in Areas 2W and 27. All available biological data on total harvest, spawn deposition, and age and size composition of the spawning runs were used to determine current abundance levels. The 2007 season represented the first year of post-Larocque assessment and resulted in a substantially reduced data collection program. Reduced biological sample collection occurred in all areas and dive survey coverage was reduced. Additionally, unusually late spawning in most areas presented logistical difficulties and some deep spawning on the west coast of Vancouver Island was not adequately surveyed. Nevertheless, all available data were included in and summarized from an Access database and utilized in the stock assessment. On a coast-wide basis, herring abundance decreased in 2007. The estimated pre-fishery biomass was 117,400 metric tonnes (t), which represents a 13% decrease from the 2006 stock level (135,100 t). The recruitment of the 2004-year class in 2007 was poor for the Central Coast and west coast of Vancouver Island. The Queen Charlotte Islands and Strait of Georgia had average recruitment while Prince Rupert had poor to average recruitment. Abundance decreased slightly in all areas except the Queen Charlotte Islands where there was a moderate increase. The stock projections for 2008 indicate reduced abundance in three assessment areas that will not support harvest: Queen Charlotte Islands, west coast of Vancouver Island, and the Central Coast. The estimated harvestable surplus of BC herring in 2008 (20% of the 2008 forecast spawning stock biomass), in the two remaining areas is 4,014 tonnes in the Prince Rupert area and 13,470 tonnes in the Strait of Georgia.

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