Browsing by Subject "South African hake"

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    2007 Routine update of the South African hake baseline assessment
    (2007) Rademeyer, Rebecca A; Butterworth, Doug S
    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 that with the highest likelihood, has been run – it is termed the ‘baseline’ assessment.
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    2013 update of the South African hake reference case assessment
    (2013) Rademeyer, Rebecca A; Butterworth, Doug S
    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 longline catch-at-length data subsequent to 2000 results in a somewhat reduced estimate of current the M. paradoxus spawning biomass.
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    Final CMP projections for the South African hake resource
    (2014) Rademeyer, Rebecca A; Butterworth, Doug S
    This document provides final CMP trial results for the revision of the SA hake OMP, following selections and requests made at the 16 September meeting of the DWG. The results cover the four CMPs identified, which are distinguished by two different target average TACs for the next decade, and by whether or not the TAC is fixed at 147 500 tons for the next two years. For the higher target average TAC (138 000 t compared to 135 000 t), M. paradoxus recovery would be about 5% and CPUE about 2% less, with attainment of MSYL delayed by about 2 years. For the options with a fixed TAC of 147 500 t for the next two years, recovery is briefly delayed, and later TACs drop lower, with lower CPUEs and higher effort levels over most of the next decade. Performance under the various robustness tests examined does not seem unsatisfactory.
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    A gender-disaggregated assessment of the South African hake resource, fitting directly to age-length keys: a new reference case
    (2009) Rademeyer, Rebecca A; Butterworth, Doug S
    The assessment methodology for the hake resource is refined to take account of recommendations made by the Panel at the December 2008 International Stock Assessment Workshop to move to a gender-disaggregated model, and to fit directly to age data and estimate growth curve parameters directly in the likelihood maximisation process. This approach proves to remove the conflict between fits to catch-at-age and catch-at-length distributions evident in earlier assessments. The current M. paradoxus female spawning biomass is estimated to be at 76% of its MSY level, while the corresponding M. capensis estimate well above this level.
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    Output from the South African hake OMP-2010 for the 2013 TAC recommendation
    (2012) Rademeyer, Rebecca A
    The TAC output from the South African hake OMP-2010 for 2013 is 156 075 t, a 7.88% increase on the 2012 TAC.
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    Proposed reference set for the South African hake resource to be used in OMP-2010 testing
    (2010) Rademeyer, Rebecca A; Butterworth, Doug S
    A Reference Set (RS) of 12 scenarios is put forward as the primary basis to be used to simulation test candidates for the revised OMP for hake, OMP-2010. The principal uncertainty axes spanned by this RS are the central year for the switch from a primarily M. capensis to a primarily M. paradoxus fishery, values for natural mortality at age, and the form of the stock recruitment relationship. The various data sets are generally reasonably fitted by these models, with the recent GLM-standardised CPUE series having the greatest influence.