An analysis of the sensitivity of stock biomass estimates derived from the daily egg production method (DEPM) to uncertainty in egg mortality rates

Abstract

In daily egg production methods (DEPMs) of estimating pelagic fish stock biomass, high variance in measured egg mortality rate is the principal source of error. A simple analytic equation was used to test the sensitivity of biomass estimates to daily egg mortality. Biomass estimates were found to be robust with regard to variation in mortality. Other sources of uncertainty can at times be more significant. High sample variance and low sensitivity suggest more optimal survey designs can be achieved by devoting fewer resources to measuring egg mortality rates. A Bayesian approach is suggested.