Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population

dc.contributor.authorButterworth, Doug S
dc.contributor.authorMoosa, Naseera
dc.contributor.authorJohnston, Susan J
dc.date.accessioned2016-04-19T13:22:14Z
dc.date.available2016-04-19T13:22:14Z
dc.date.issued2014
dc.date.updated2016-04-19T13:21:11Z
dc.description.abstractThe ability of catch-based measures (both catch itself and measures of catch-rate/CPUE such as catch-per-set) to provide reliable indices of abundance of the annual anchovy recruitment on the South African west coast is investigated. Ground truthing is provided by the annual acoustic surveys of this abundance and corresponding estimates provided when this information is utilised in population assessments. The measures considered for the fishery as a whole reflect at most a 30% increase across the turn of the century, way below the some three-fold increase from before to after that time indicated by the surveys and assessment. The same is true for similar measures from catches made close to Robben or to Dassen Island, except when catches within 10 nm of these islands are considered, though surprisingly then this result of a similar increase to the survey results does not extend to catches within 20 nm. Nevertheless the CVs about the catch within 10 nm – recruitment relationships are some 70%, which is hopelessly too large for such measures to provide meaningful and reliable predictions of anchovy recruitment. Thus this study has failed to reveal any evidence to support the suggestion that anchovy catch- related measures might provide meaningful indices of anchovy recruitment abundance.en_ZA
dc.identifier.apacitationButterworth, D. S., Moosa, N., & Johnston, S. J. (2014). <i>Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18988en_ZA
dc.identifier.chicagocitationButterworth, Doug S, Naseera Moosa, and Susan J Johnston <i>Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2014. http://hdl.handle.net/11427/18988en_ZA
dc.identifier.citationButterworth, D. S., Moosa, N., & Johnston, S. J. (2014). Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population?. MARAM: University of Cape Town.en_ZA
dc.identifier.ris TY - Working Paper AU - Butterworth, Doug S AU - Moosa, Naseera AU - Johnston, Susan J AB - The ability of catch-based measures (both catch itself and measures of catch-rate/CPUE such as catch-per-set) to provide reliable indices of abundance of the annual anchovy recruitment on the South African west coast is investigated. Ground truthing is provided by the annual acoustic surveys of this abundance and corresponding estimates provided when this information is utilised in population assessments. The measures considered for the fishery as a whole reflect at most a 30% increase across the turn of the century, way below the some three-fold increase from before to after that time indicated by the surveys and assessment. The same is true for similar measures from catches made close to Robben or to Dassen Island, except when catches within 10 nm of these islands are considered, though surprisingly then this result of a similar increase to the survey results does not extend to catches within 20 nm. Nevertheless the CVs about the catch within 10 nm – recruitment relationships are some 70%, which is hopelessly too large for such measures to provide meaningful and reliable predictions of anchovy recruitment. Thus this study has failed to reveal any evidence to support the suggestion that anchovy catch- related measures might provide meaningful indices of anchovy recruitment abundance. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population TI - Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population UR - http://hdl.handle.net/11427/18988 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/18988
dc.identifier.vancouvercitationButterworth DS, Moosa N, Johnston SJ. Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population. 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18988en_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.titleDo catch-based indices provide a reliable index of annual recruitment for the South African anchovy populationen_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:
Butterworth_Do_catch_based_indices_2014.pdf
Size:
1.24 MB
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