Estimating and decomposing total uncertainty for survey-based abundance estimates of Norwegian spring-spawning herring
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http://hdl.handle.net/11250/100887Utgivelsesdato
2006Metadata
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We demonstrate how the total uncertainty of the abundance estimate and abundanceat-
age estimate of Norwegian spring-spawning herring are affected by uncertainty in the
parameters of vessel avoidance, shadowing and depth dependent target strength, and
uncertainty from trawl hauls and spatial-temporal coverage. The total uncertainty is
decomposed into the sum of the contribution from each source separately. In addition,
we highlight the potentially dramatic combined effect of correcting for vessel avoidance,
shadowing and depth dependent target strength on the abundance estimate. The main
framework is believed to be a promising tool for focusing the effort for reducing the
uncertainty in the abundance estimates. The method is applied to data from surveys on
the over-wintering stock in the Vestfjord system and Vesteraalen in northern Norway in
November/December in the years 2001–2004.
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ICES CM documents2006/I:13