Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode

dc.contributor.authorDe Moor, Carryn L
dc.contributor.authorButterworth, Doug S
dc.date.accessioned2016-04-11T14:39:37Z
dc.date.available2016-04-11T14:39:37Z
dc.date.issued2011
dc.date.updated2016-04-11T14:38:27Z
dc.description.abstractThe operating model (OM) for the South African anchovy resource has been updated from that used to develop OMP-08 given four more years of data and a revised time series of commercial catch. A Hockey Stick stock recruitment relationship, and the same median juvenile and adult natural mortality rates as in previous assessments are used. When considering the Beverton Holt, Ricker and Hockey stick stock recruitment relationships, AICc model selection criterion do not show strong support for one relationship over another, yet the carrying capacity at the posterior mode differs considerably between the Hockey Stick and other relationships. Two base case hypotheses are chosen: one estimates random effects about adult natural mortality over time while the other assumes time-invariant annual adult natural mortality. There has been a decrease in recruitment residual standard deviation and in recruitment autocorrelation for this updated OM compared to that used in previous OMs. The impact of this on the appropriate choices of a risk definition and threshold for the new OMP to be developed needs to be considered. The resource abundance remains above the historic average, with a model-estimated 1+ biomass of 2.2-2.4 million tons in November 2010, having provided 8 years of above average recruitment in the past 11 years. The harvest proportion over the past 11 years has not exceeded 0.13.en_ZA
dc.identifier.apacitationDe Moor, C. L., & Butterworth, D. S. (2011). <i>Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18759en_ZA
dc.identifier.chicagocitationDe Moor, Carryn L, and Doug S Butterworth <i>Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2011. http://hdl.handle.net/11427/18759en_ZA
dc.identifier.citationde Moor, C. L., & Butterworth, D. S. (2011). Assessment of the South African anchovy resource using data from 1984–2010: results at the posterior mode. MARAM: University of Cape Town.en_ZA
dc.identifier.ris TY - Working Paper AU - De Moor, Carryn L AU - Butterworth, Doug S AB - The operating model (OM) for the South African anchovy resource has been updated from that used to develop OMP-08 given four more years of data and a revised time series of commercial catch. A Hockey Stick stock recruitment relationship, and the same median juvenile and adult natural mortality rates as in previous assessments are used. When considering the Beverton Holt, Ricker and Hockey stick stock recruitment relationships, AICc model selection criterion do not show strong support for one relationship over another, yet the carrying capacity at the posterior mode differs considerably between the Hockey Stick and other relationships. Two base case hypotheses are chosen: one estimates random effects about adult natural mortality over time while the other assumes time-invariant annual adult natural mortality. There has been a decrease in recruitment residual standard deviation and in recruitment autocorrelation for this updated OM compared to that used in previous OMs. The impact of this on the appropriate choices of a risk definition and threshold for the new OMP to be developed needs to be considered. The resource abundance remains above the historic average, with a model-estimated 1+ biomass of 2.2-2.4 million tons in November 2010, having provided 8 years of above average recruitment in the past 11 years. The harvest proportion over the past 11 years has not exceeded 0.13. DA - 2011 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode TI - Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode UR - http://hdl.handle.net/11427/18759 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/18759
dc.identifier.vancouvercitationDe Moor CL, Butterworth DS. Assessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior mode. 2011 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18759en_ZA
dc.languageengen_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.titleAssessment of the South African anchovy resource using data from 1984 – 2010: results at the posterior modeen_ZA
dc.typeWorking Paperen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceResearch paperen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
de_Moor_Assessment_South_2011.pdf
Size:
535.5 KB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.72 KB
Format:
Item-specific license agreed upon to submission
Description:
Collections