Publication Abstract

Investigating the use of proxies for fecundity to improve the management of western horse mackeral

J.A. De Oliveira, B. Roel, M. Dickey-Collas, C.D. Darby

Observations of fecundity from the most recent Western horse mackerel spawning stock biomass survey suggest that the species is an indeterminate spawner and therefore the current model of fecundity, used in the calibration of the stock assessment, may be inappropriate. The stock is assessed by fitting a linked Separable and ADAPT VPA-based model to the catch-at-age data and to the egg production estimates. The assumption is made that egg production and spawning stock biomass are linked by a constant but unknown fecundity parameter, estimated within the model. In this study, the sensitivity of the model structure to alternative fecundity relationships is explored. The introduction of models linking biological indicators of fecundity, such as lipid content or feeding intensity during the spawning season is examined. The impact on the perception and management of this stock is evaluated within a simulation framework. Simulations suggest that care must be taken when incorporating time series of proxies when the underlying relationships with fecundity are poorly described, weak or based on few data.

Reference:

J.A. De Oliveira, B. Roel, M. Dickey-Collas, C.D. Darby (2004) Investigating the use of proxies for fecundity to improve the management of western horse mackeral.