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2003 updated assessment for the Merluccius paradoxus hake resource off the south and west coasts

Author: Rademeyer, Rebecca A ; Butterworth, Doug S Date: 2003 This document presents an updated assessment of the M. paradoxus hake resource off the south and west coasts of South Africa. The previous assessment of this resource is described in Rademeyer and Butterworth (2002). Read more
The 2004 age-structured production model assessments and projections for the South Coast rock lobster resource

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2004 The assessment conducted in 2003 has been routinely extended, taking account of a further year’s catch, CPUE and catch-at-age data. CPUE shows a continuation of the increase that commenced in 1998. Results are generally more optimistic than ... Read more
The 2004 re-assessment of the South African sardine and anchovy populations to take account of revisions to earlier data and recent record abundances

Author: de Moor, Carryn L ; Butterworth, Doug S Date: 2009 Hydroacoustic surveys off the coast of South Africa over the early years of the 21st century indicated that both the sardine Sardinops sagax and anchovy Engraulis encrasicolus populations had simultaneously reached record abundances. The South ... Read more
The 2005 Age-Structured Production Model assessments and constant catch projections for the south coast rock lobster resource

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2005 The 2005 assessment was routinely extended, taking account of a further year’s catch, CPUE and catch-at-age data. CPUE shows a continuation of the increase that commenced in 1998. However, sustainable yield estimates are generally less than ... Read more
The 2006 age-structured production model assessments and projections for the South Coast rock lobster resource-routine update

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2006 The assessment conducted in 2006 has been routinely extended, taking account of a further year’s catch, CPUE and catch-at-age data. CPUE shows a continuation of the increase that commenced in 1998. The sustainable yield estimates are generally ... Read more
2006 assessment of the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity

Author: Brandão, Anabela ; Butterworth, Doug S Date: 2006 The ASPM assessment of the Prince Edward Islands toothfish resource by Brandão and Butterworth (2005) that permitted annual fluctuations about a deterministic stockrecruitment relationship is updated to take account of further catch, GLM ... Read more
The 2007 Age-Structured Production Model assessments and projections for the South Coast rock lobster resource-routine update using model fitting to catch-at-age data

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2007 The assessment conducted in 2006 (WG/06/06/WCRL3) has been routinely extended, taking account of a further year’s catch, CPUE and catch-at-age data. The observed CPUE shows a slight decrease for 2005 (2005/06 season). The sustainable yield ... Read more
The 2007 age-structured production model assessments and projections for the South Coast rock lobster resource-routine update using Pope's approximation model fitting to catch-at-age data including scenarios for time-varying selectivity

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2007 The assessment conducted in 2006 (WG/06/06/WCRL3) has been routinely extended (except that the Baranov equation has been replaced by Pope’s approximation), taking account of a further year’s catch, CPUE and catch-at-age data. The observed ... Read more
2007 assessment of the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity

Author: Brandão, Anabela ; Butterworth, Doug S Date: 2006 The ASPM assessment of the Prince Edward Islands toothfish resource by Brandão and Butterworth (2006) that permitted annual fluctuations about a deterministic stock-recruitment relationship is updated to take account of further catch, GLM ... Read more
2007 Routine update of the South African hake baseline assessment

Author: Rademeyer, Rebecca A ; Butterworth, Doug S Date: 2007 This paper presents a routine update of the South African hake assessment, including new commercial (catches and CPUE) and survey (abundance estimates and catch-at-age) data. Only one scenario (M1-H1-C1-SR2) of the Reference Set, which is ... Read more
2008 routine update of the South African hake resource baseline assessment

Author: Rademeyer, Rebecca A ; Butterworth, Doug S Date: 2008 This paper presents a routine update of the South African hake assessment, including new commercial (catches and CPUE) and survey (abundance estimates) data. This update is for a “baseline” assessment, chosen to correspond to the scenario ... Read more
2009 updated stock assessments for West Coast rock lobster

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2009 The west coast rock lobster assessment of 20061 based on data to 2004 is updated to include data up to 2008. Over the last four years the exploitable biomass trend is upwards for Areas 7 and 8 and the resource as a whole, but downwards for ... Read more
2010 Estimates of sustainable rock lobster yield for the four islands of the Tristan da Cunha group

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2010 A simple replacement yield model is fitted to CPUE and annual catch data from 1997 for the four islands of the Tristan da Cunha group. The results suggest that the current TAC be maintained, with a slight increase (perhaps 5 tons) to the ... Read more c b
The 2010 operational management procedure for the South African Merluccius paradoxus and M.?capensis resources

Author: Rademeyer, Rebecca A ; Fairweather, T ; Glazer, Jean Patricia ; Leslie, R L ; Butterworth, Doug S Date: 2010 The algorithm for the 2010 Operational Management Procedure (OMP) to provide TAC recommendations for the South African Merluccius paradoxus and M. capensis resources is empirical. It combines an increase or decrease of the TAC in relation to ... Read more
2012 South coast rock lobster operating models-some initial results

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2012 Initial updated assessments are developed for the South Coast rock lobster resource incorporating the recently revised estimates of somatic growth rate by area developed by OLRAC, and fitting to area-specific CPUE and scientific catch-at-length ... Read more
2013 Update of the Reference Set of Operating Models used in testing Candidate OMPs for the South African hake resource

Author: Rademeyer, Rebecca A ; Butterworth, Doug S Date: 2013 A Reference Set (RS) of 12 scenarios was selected as the primary basis to be used to simulation test candidates for OMP-2011 (Rademeyer and Butterworth, 2010). This paper presents an update of this RS, based on updated commercial data (catches, ... Read more
2013 update of the South African hake reference case assessment

Author: Rademeyer, Rebecca A ; Butterworth, Doug S Date: 2013 The Reference Case assessment of the SA hake resource is updated using unchanged methodology from that used in developing the existing OMP, but with revised and updated data sets. The only change of particular note is the inclusion of new ... Read more
2015 updated South Coast Rock Lobster assessment results

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2015 The 2013 assessment of the resource is updated given three further years of data now available. Recruitment is estimated to have been poor over the further three seasons for which this can now be estimated. The spawning biomass trajectory ... Read more
The 2016 Horse Mackerel Assessment Model

Author: Johnston, Susan J ; Butterworth, Doug S Date: Sep 2016 Furman (2014) developed and described the horse mackerel assessment model for his MSc thesis. This document extracts pertinent sections from his thesis which describe the population assessment model, and provides a description of assumptions ... Read more c b
2016 Horse Mackerel projections

Author: Johnston, Susan J ; Butterworth, Doug S Date: Oct 2016 The projections conducted in 2015 are updated to include the further data now available. The results are somewhat more positive than previously as a result of the CPUE for 2015, although still low, being higher than that for 2014. Nevertheless, ... Read more

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