Can anchovy age structure be estimated from length distribution data collected during surveys?

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dc.contributor.authorDe Moor, Carryn L
dc.contributor.authorButterworth, Doug S
dc.contributor.authorCoetzee, J C
dc.date.accessioned2016-03-14T08:47:01Z
dc.date.available2016-03-14T08:47:01Z
dc.date.issued2013
dc.date.updated2016-03-14T08:42:26Z
dc.description.abstractHistorically, a time-series of proportions-at-age 1 from annual November hydro-acoustic surveys has been used to inform the assessment of, and in particular the choice of appropriate values for juvenile and adult natural mortality for, the South African anchovy Engraulis encrasicolus. However, information from direct ageing is limited and almost two decades old. A new method is developed to estimate the annual proportions of anchovy at age 1 directly from the population length distributions estimated from samples taken during the November surveys. This method involves modelling the annual length distributions of age 1 and age 2+ anchovy. The analysis provides a new time-series of proportions-at-age 1, together with associated standard errors, for input into assessments of the resource. The results also caution against the danger of scientists reading more information into data than is really there.en_ZA
dc.identifierhttp://dx.doi.org/10.2989/1814232X.2013.830991
dc.identifier.apacitationDe Moor, C. L., Butterworth, D. S., & Coetzee, J. C. (2013). Can anchovy age structure be estimated from length distribution data collected during surveys?. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/17745en_ZA
dc.identifier.chicagocitationDe Moor, Carryn L, Doug S Butterworth, and J C Coetzee "Can anchovy age structure be estimated from length distribution data collected during surveys?." <i>African Journal of Marine Science</i> (2013) http://hdl.handle.net/11427/17745en_ZA
dc.identifier.citationde Moor, C. L., Butterworth, D. S., & Coetzee, J. C. (2013). Can anchovy age structure be estimated from length distribution data collected during surveys?. African Journal of Marine Science, 35(3), 335-342.en_ZA
dc.identifier.issn1814-232Xen_ZA
dc.identifier.ris TY - Journal Article AU - De Moor, Carryn L AU - Butterworth, Doug S AU - Coetzee, J C AB - Historically, a time-series of proportions-at-age 1 from annual November hydro-acoustic surveys has been used to inform the assessment of, and in particular the choice of appropriate values for juvenile and adult natural mortality for, the South African anchovy Engraulis encrasicolus. However, information from direct ageing is limited and almost two decades old. A new method is developed to estimate the annual proportions of anchovy at age 1 directly from the population length distributions estimated from samples taken during the November surveys. This method involves modelling the annual length distributions of age 1 and age 2+ anchovy. The analysis provides a new time-series of proportions-at-age 1, together with associated standard errors, for input into assessments of the resource. The results also caution against the danger of scientists reading more information into data than is really there. DA - 2013 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2013 SM - 1814-232X T1 - Can anchovy age structure be estimated from length distribution data collected during surveys? TI - Can anchovy age structure be estimated from length distribution data collected during surveys? UR - http://hdl.handle.net/11427/17745 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17745
dc.identifier.urihttp://www.tandfonline.com/doi/abs/10.2989/1814232X.2013.830991
dc.identifier.vancouvercitationDe Moor CL, Butterworth DS, Coetzee JC. Can anchovy age structure be estimated from length distribution data collected during surveys?. African Journal of Marine Science. 2013; http://hdl.handle.net/11427/17745.en_ZA
dc.languageengen_ZA
dc.publisherNational Inquiry Services Centre (NISC)en_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceAfrican Journal of Marine Scienceen_ZA
dc.source.urihttp://www.tandfonline.com/toc/tams20/current
dc.subject.otherAnchovy
dc.subject.otherEffective sample size
dc.subject.otherLength distribution
dc.subject.otherProportion-at-age
dc.subject.otherProportion-at-length
dc.titleCan anchovy age structure be estimated from length distribution data collected during surveys?en_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsAnchovyen_ZA
uct.subject.keywordsEffective sample sizeen_ZA
uct.subject.keywordsLength distributionen_ZA
uct.subject.keywordsProportion-at-ageen_ZA
uct.subject.keywordsProportion-at-lengthen_ZA
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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