Research Document 1998/97
Area assessment methods for 4T fall spawning herring
By R. Claytor, A. Clay, and C. LeBlanc
Abstract
A method is proposed for doing area assessments of 4T fall spawning herring. The method includes estimating biomass indices and relative fishing mortalities using acoustic data collected during regular fishing activity and surveys. Relative fishing mortality for each night of fishing would be estimated by dividing the catch by the biomass index. A weighted fishing mortality could be estimated for the season in each area by weighting the nightly fishing mortalities by the biomass estimates for each night. This method would use information collected from purse seiners and gillnetters.
A method for estimating recruitment using variable mesh size nets is proposed.
Issues to be resolved are: standardization of analytical technique for biomass estimates including how the polygons defining the boundaries of the estimated area or fishing grounds are made, variation among boats, the effect of averaging to reduce data points on final estimates, how catch locations may be included, and how out of season surveys should affect overall relative F calculation.
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