Assessment of the South African anchovy resource

Cunningham, Carryn L; Butterworth, Doug S

Assessment of the South African anchovy resource

Working Paper

2007

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 from the last assessment (Cunningham and Butterworth 2004) to take account of new data and data adaptations as follows: i) an update in the time series of November spawner biomass and May recruitment estimates from acoustic surveys, such that the new time series reflects uncapped estimates of biomass based on new target strength calculations throughout, ii) a new method of using a monthly cut-off length to split recruits from 1-year-olds in the commercial catch (previously recruits and 1-year-olds were assumed to be caught in different months), and iii) new data for 2004 to 2006 which were not included in the last assessment conducted in 2004. In addition, this assessment has been modified from previous assessments to include: iv) a plus group of age 4 (previously anchovy were assumed to spawn at age 4 and then die), v) accounting for the introduction of the additional season by assuming the juvenile catch was taken in a pulse on 15th June prior to 1999 and on 15th July from 1999 onwards, and iv) the adult catch now assumed to be taken in a pulse on 1st April (previously assumed to be taken halfway between November and March). This document details the updated assessment model and gives the assessment results for the base case and robustness tests.

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