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Research Document - 1999/178

Stock assessment for British Columbia herring in 1999 and forecasts of the potential catch in 2000.

By J. Schweigert and C. Fort

Abstract

Herring stock abundance in British Columbia waters was assessed for 1999 and forecasts were made for 2000 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 1999 was 187,500. This represents a 2 percent decrease from 1998 abundance levels. This slight decrease reflects the recruitment of a poor 1996 year-class in 1999 in most areas of the coast.

Forecasts of the pre-fishery spawning stock biomass in 2000 are presented for both models. Stock forecasts for the northern stock assessment regions are 120,000 and 83,000 tonnes for the southern regions assuming average recruitment to all areas based on the age-structured model.

The estimated harvestable surplus in 2000 (20 percent of the 2000 forecast herring run) is 40,500 tonnes for the entire B.C. coast assuming average recruitment to all areas. However, since consensus on stock levels for each assessment region may change as a result of PSARC review of these data, forecast run sizes, and harvestable surpluses, are subject to change.

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