Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource

dc.contributor.authorButterworth, Doug S
dc.contributor.authorRademeyer, Rebecca A
dc.date.accessioned2016-04-20T12:01:35Z
dc.date.available2016-04-20T12:01:35Z
dc.date.issued2009
dc.date.updated2016-04-20T11:58:44Z
dc.description.abstractThis document reports refinements to the survey-based SCAA assessments reported at an earlier meeting in Vigo, and attempts to provide results for the set of future analyses requested there. Particular attention has been paid to attempting to reduce the residual patterning evident in earlier assessments through taking further account of serial correlation. These efforts seem to have been reasonably successful for the overall survey indices and commercial catch-at-age proportions, but less so for the survey catch-at-age proportions, which consequently remain somewhat overweighted in the fitting process. A simpler agestructured production model is also fitted to the data, and gives similar results to the New Baseline SCAA assessment that is developed, with Bayesian estimates of precision computed for both these approaches. Despite these efforts to incorporate serial correlation, some conflict remains amongst the different sets of input data, and partly in consequence the absolute scale of biomass is poorly determined by assessments. The most pessimistic (in stock status terms) of the SCAA variants considered produce biomass estimates that do not differ that greatly from those from XSA. Importantly however, even in those cases the SCAA assessments provide results for recent years more in line with survey index (and CPUE) trends, and give more positive projections for future abundance: for example all SCAA projections under a constant TAC of 22750 tons increase, whereas XSA projects a decrease in those circumstances.en_ZA
dc.identifier.apacitationButterworth, D. S., & Rademeyer, R. A. (2009). <i>Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/19012en_ZA
dc.identifier.chicagocitationButterworth, Doug S, and Rebecca A Rademeyer <i>Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2009. http://hdl.handle.net/11427/19012en_ZA
dc.identifier.citationButterworth, D. S., & Rademeyer, R. A. (2009). Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource. MARAM: University of Cape Town.en_ZA
dc.identifier.ris TY - Working Paper AU - Butterworth, Doug S AU - Rademeyer, Rebecca A AB - This document reports refinements to the survey-based SCAA assessments reported at an earlier meeting in Vigo, and attempts to provide results for the set of future analyses requested there. Particular attention has been paid to attempting to reduce the residual patterning evident in earlier assessments through taking further account of serial correlation. These efforts seem to have been reasonably successful for the overall survey indices and commercial catch-at-age proportions, but less so for the survey catch-at-age proportions, which consequently remain somewhat overweighted in the fitting process. A simpler agestructured production model is also fitted to the data, and gives similar results to the New Baseline SCAA assessment that is developed, with Bayesian estimates of precision computed for both these approaches. Despite these efforts to incorporate serial correlation, some conflict remains amongst the different sets of input data, and partly in consequence the absolute scale of biomass is poorly determined by assessments. The most pessimistic (in stock status terms) of the SCAA variants considered produce biomass estimates that do not differ that greatly from those from XSA. Importantly however, even in those cases the SCAA assessments provide results for recent years more in line with survey index (and CPUE) trends, and give more positive projections for future abundance: for example all SCAA projections under a constant TAC of 22750 tons increase, whereas XSA projects a decrease in those circumstances. DA - 2009 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2009 T1 - Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource TI - Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource UR - http://hdl.handle.net/11427/19012 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/19012
dc.identifier.vancouvercitationButterworth DS, Rademeyer RA. Extensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resource. 2009 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/19012en_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.titleExtensions to SCAA applications reported in: further applications of statistical catch-at-age assessment methodology to the 2J3K-O Greenland halibut resourceen_ZA
dc.typeWorking Paperen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceResearch paperen_ZA
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