Assessment of the South African anchovy resource using data from 1984-2009

De Moor, Carryn L; Butterworth, Doug S

Assessment of the South African anchovy resource using data from 1984-2009

Working Paper

2010

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

The assessment of the South African anchovy resource has been updated given three more years of data and a revised time series of commercial catch. The base case hypothesis has the same juvenile and adult natural mortality rates as previous assessments, but a Beverton Holt stock recruitment relationship is now assumed instead of a hockey stick with fixed inflection point based on the AICc selection criterion. This change has resulted in a large increase in median posterior carrying capacity from previous assessments. There has been a decrease in recruitment residual standard deviation and in recruitment serial autocorrelation with the newer assessments. The impact of this on the appropriate choice of a risk definition and threshold for the new OMP to be developed next year will be considered early in the OMP development phase. The resource abundance remains above average, with a model-estimated 1+ biomass of 3.5 million tons in November 2009, and the resource has produced 8 years of above average recruitment in the past 11 years. The harvest proportion in the past 9 years has not exceeded 0.14.

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