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

 

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dc.contributor.author De Moor, Carryn L
dc.contributor.author Butterworth, Doug S
dc.contributor.author Coetzee, J C
dc.date.accessioned 2016-03-14T08:47:01Z
dc.date.available 2016-03-14T08:47:01Z
dc.date.issued 2013
dc.identifier http://dx.doi.org/10.2989/1814232X.2013.830991
dc.identifier.citation de 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.issn 1814-232X en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17745
dc.identifier.uri http://www.tandfonline.com/doi/abs/10.2989/1814232X.2013.830991
dc.description.abstract 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. en_ZA
dc.language eng en_ZA
dc.publisher National Inquiry Services Centre (NISC) en_ZA
dc.source African Journal of Marine Science en_ZA
dc.source.uri http://www.tandfonline.com/toc/tams20/current
dc.subject.other Anchovy
dc.subject.other Effective sample size
dc.subject.other Length distribution
dc.subject.other Proportion-at-age
dc.subject.other Proportion-at-length
dc.title Can anchovy age structure be estimated from length distribution data collected during surveys? en_ZA
dc.type Journal Article en_ZA
dc.date.updated 2016-03-14T08:42:26Z
uct.type.publication Research en_ZA
uct.type.resource Article en_ZA
uct.subject.keywords Anchovy en_ZA
uct.subject.keywords Effective sample size en_ZA
uct.subject.keywords Length distribution en_ZA
uct.subject.keywords Proportion-at-age en_ZA
uct.subject.keywords Proportion-at-length en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Marine Resource Assessment and Management Group en_ZA


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