Research Document - 2000/165

Stock assessment for British Columbia herring in 2000 and forecasts of the potential catch in 2001.

By J. Schweigert

Abstract

Herring stock abundance in British Columbia waters was assessed for 2000 and forecasts were made for 2001 using two analytical methods: (1) escapement model; and (2) age-structured model. These models have been applied to assess herring abundance since 1984 and no significant changes were implemented in either model in conducting the current assessment. 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. No significant problems were evident in the extent and comprehensiveness of the data collections. Coastwide, the estimated pre-fishery stock biomass for all assessment regions in 2000 was 157,000 tonnes based on the escapement model. This represents a 16% decrease from 1999 abundance levels. This reflects the recruitment of an average 1997 year-class in all areas except the west coast of Vancouver Island where recruitment was poor.

Forecasts of the pre-fishery spawning stock biomass in 2001 are presented for both models but PSARC adopted forecasts from the escapement model in all areas. Stock forecasts for the northern stock assessment regions total 66,000 tonnes and 97,000 tonnes for the southern regions assuming average recruitment to all areas except the west coast of Vancouver Island where recruitment is expected to again be poor.

The estimated harvestable surplus in 2001 (20% of the 2001 forecast herring run) is 28,500 tonnes for the entire B.C. coast. Forecasts indicate that abundance in the Queen Charlotte Islands and west coast of Vancouver Island will be below the Cutoff level so no roe fisheries are anticipated in these assessment regions.

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