Research Document - 2009/019

Stock Assessment for British Columbia Herring in 2008 and Forecasts of the Potential Catch in 2009

By J. Schweigert, L.B. Christensen, and V. Haist

Abstract

Herring stock abundance in British Columbia waters was assessed for 2008 and forecasts were made for 2009 using a slight variation on the herring catch-age model (HCAMv2) adopted last year (HCAM). Assessments were completed 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 2008 season represented the second year of post-Larocque assessment and again resulted in a reduced data collection program. Reduced biological sample collection occurred in all areas and dive survey coverage was reduced. Additionally, some deep spawning was detected on the west coast of Vancouver Island but 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 2008. The estimated pre-fishery biomass was 77,500 metric tonnes (t), which represents a 27% decrease, from the 2007 stock level (105,100 t). The recruitment of the 2005-year class in 2008 was generally poor throughout the coast, a result of unusual environmental conditions during the egg to juvenile stage. Abundance decreased slightly in all areas but to a greater extent in the two southern stocks. The stock projections for 2009 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 2009 (20% of the 2009 forecast spawning stock biomass); in the two remaining areas is 3,468 tonnes in the Prince Rupert area and 11,797 tonnes in the Strait of Georgia.

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