Stock assessments for British Columbia herring in 1986 and forecasts of the potential catch in 1987 / by V. Haist, J.F. Schweigert and D. Fournier.: Fs97-4/1929E-PDF

"Herring stock abundance in British Columbia waters was assessed for 1986, and forecasts were made for 1987 using two methods: (1) escapement model, and (2) age-structured model, analysis. The escapement model was modified to introduce age structure information and explicitly separate growth and recruitment. The age-structured model was modified to incorporate an availability term to estimate partial recruitments. Diving spawn survey data was incorporated into the escapement model wherever available. Forecasts of pre-fishery biomass are obtained by weighting the estimates from the two models. The forecasts, assuming average recruitment, are for 66,810 tonnes to the northern and 101,270 tonnes to the southern stock assessment regions. These estimates represent a substantial increase over 1986 levels, reflecting average or better recruitments to all the southern areas during the last spawning run. The recommended 1987 catch (20% of the 1987 forecast herring run for stocks above CUTOFF levels) for the entire B.C. coast is 33,470 tonnes. All areas should be available to the fishery in 1987. However, concern has been noted for the Queen Charlotte Islands stocks where spawn deposition has dropped markedly and the dominant 1977 year-class has all but disappeared from the stock"--Abstract, page iv.

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