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Research Document - 1999/021

1998 Stock assessment for British Columbia herring in 1998 and forecasts of the potential catch in 1999

By J.F. Schweigert, C. Fort and R. Tanasichuk

Abstract

Herring stock abundance in British Columbia waters was assessed for 1998 and forecasts were made for 1999 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 1998 was 207,800 tonnes which represents a 12% increase from 1997 abundance levels. This increase reflects the recruitment of a strong 1995 year-class in 1998 in northern areas and average in southern areas

Forecasts of the pre-fishery spawning stock biomass in 1999 were obtained from the escapement model estimates, a departure from previous years when the estimates from the two analytical models were averaged. Stock forecasts for the northern stock assessment regions are 96,100 and 124,000 tonnes for the southern regions assuming average recruitment to all areas.

The recommended 1999 catch (20% of the 1999 forecast herring run) is 44,000 tonnes for the entire B.C. coast assuming average recruitment to all areas. However, since concensus 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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