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

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.