Assessing the South African sardine resource: two stocks rather than one?

 

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dc.contributor.author De Moor, Carryn L
dc.contributor.author Butterworth, Doug S
dc.date.accessioned 2016-04-18T11:18:42Z
dc.date.available 2016-04-18T11:18:42Z
dc.date.issued 2015
dc.identifier http://dx.doi.org/http://www.tandfonline.com/doi/full/10.2989/1814232X.2015.1009166
dc.identifier.citation de Moor, C. L., & Butterworth, D. S. (2015). Assessing the South African sardine resource: two stocks rather than one?. African Journal of Marine Science, 37(1), 41-51. en_ZA
dc.identifier.issn 1814-232X en_ZA
dc.identifier.uri http://hdl.handle.net/11427/18933
dc.description.abstract Sardine Sardinops sagax distributed off the west and south coasts of South Africa have traditionally been assumed to comprise a single well-mixed stock for assessment and management purposes. New research, however, lends weight to the possibility of two stocks in this region. A precautionary management approach thus needs to consider the impact of management decisions on the hypothesised two individual stocks as well as on the resource as a whole. As a first step in this process, Bayesian assessments of South African sardine are presented, which compare results for the traditional single-stock hypothesis with those that follow from a new two-mixing-stock hypothesis. Recruits from the west stock are assumed to move to and remain part of the south stock in annual pulses of varying size. This movement is estimated to be appreciable, and to take place from a substantially more productive west stock to the south stock. This immigration makes a greater contribution to the south-stock biomass than do years of above-average south-stock recruitment. Importantly, this two-mixing-stock hypothesis is shown to be consistent with the data available. Further alternative sardine stock-structure hypotheses suggested by the most recent data are discussed. 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/doi/abs/10.2989/1814232X.2015.1009166
dc.title Assessing the South African sardine resource: two stocks rather than one? en_ZA
dc.type Journal Article en_ZA
dc.date.updated 2016-04-18T11:14:20Z
uct.type.publication Research en_ZA
uct.type.resource Article en_ZA
uct.subject.keywords Assessment en_ZA
uct.subject.keywords Multiple stocks en_ZA
uct.subject.keywords Sardinops sagax en_ZA
uct.subject.keywords Stock structure en_ZA
uct.subject.keywords Two-mixing-stock hypothesis 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
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation De Moor, C. L., & Butterworth, D. S. (2015). Assessing the South African sardine resource: two stocks rather than one?. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/18933 en_ZA
dc.identifier.chicagocitation De Moor, Carryn L, and Doug S Butterworth "Assessing the South African sardine resource: two stocks rather than one?." <i>African Journal of Marine Science</i> (2015) http://hdl.handle.net/11427/18933 en_ZA
dc.identifier.vancouvercitation De Moor CL, Butterworth DS. Assessing the South African sardine resource: two stocks rather than one?. African Journal of Marine Science. 2015; http://hdl.handle.net/11427/18933. en_ZA
dc.identifier.ris TY - Journal Article AU - De Moor, Carryn L AU - Butterworth, Doug S AB - Sardine Sardinops sagax distributed off the west and south coasts of South Africa have traditionally been assumed to comprise a single well-mixed stock for assessment and management purposes. New research, however, lends weight to the possibility of two stocks in this region. A precautionary management approach thus needs to consider the impact of management decisions on the hypothesised two individual stocks as well as on the resource as a whole. As a first step in this process, Bayesian assessments of South African sardine are presented, which compare results for the traditional single-stock hypothesis with those that follow from a new two-mixing-stock hypothesis. Recruits from the west stock are assumed to move to and remain part of the south stock in annual pulses of varying size. This movement is estimated to be appreciable, and to take place from a substantially more productive west stock to the south stock. This immigration makes a greater contribution to the south-stock biomass than do years of above-average south-stock recruitment. Importantly, this two-mixing-stock hypothesis is shown to be consistent with the data available. Further alternative sardine stock-structure hypotheses suggested by the most recent data are discussed. DA - 2015 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 - 2015 SM - 1814-232X T1 - Assessing the South African sardine resource: two stocks rather than one? TI - Assessing the South African sardine resource: two stocks rather than one? UR - http://hdl.handle.net/11427/18933 ER - en_ZA


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