Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios

 

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dc.contributor.author Fairweather, Tracey
dc.contributor.author Glazer, Jean
dc.contributor.author Leslie, Rob
dc.contributor.author de Decker, Michelle
dc.contributor.author Johnston, Susan
dc.contributor.author Butterworth, Doug S
dc.date.accessioned 2016-04-05T09:43:51Z
dc.date.available 2016-04-05T09:43:51Z
dc.date.issued 2009
dc.identifier.citation Fairweather, T., Glazer, J., Leslie, R., de Decker, M., Johnson, S. & Butterworth, D. (2009). Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios. MCM/2009/OCT/SWG-DEM/72 en_ZA
dc.identifier.uri http://hdl.handle.net/11427/18560
dc.description.abstract The checks carried out on the hake offshore trawl catch and effort data, which provide the basis to split the catches by species and to obtain GLM-standardised CPUE indices of abundance by species, have focused on two separate steps. The first was a re-extract of the data from the original files to check for possible errors in the earlier extracts (this applies to the subset of the data for which size composition information can be unambiguously extracted). The second step was to increase the proportion of the data utilised (and at the same time to check for possible selection biases in the existing sample) by assigning size composition to drags for which this information was not directly available, on the basis of the average for other vessels for which this was available for the area and time at which the fishing concerned took place. The first step revealed a problem with extractions over the last few years which at times for certain vessels had linked the accumulated catch for the day with only the effort for the last trawl of the day, rather than for all trawls that day combined. en_ZA
dc.language eng en_ZA
dc.title Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios en_ZA
dc.type Working Paper en_ZA
dc.date.updated 2016-04-05T08:07:59Z
uct.type.publication Research en_ZA
uct.type.resource Research paper 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 Fairweather, T., Glazer, J., Leslie, R., de Decker, M., Johnston, S., & Butterworth, D. (2009). <i>Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18560 en_ZA
dc.identifier.chicagocitation Fairweather, Tracey, Jean Glazer, Rob Leslie, Michelle de Decker, Susan Johnston, and Doug Butterworth <i>Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2009. http://hdl.handle.net/11427/18560 en_ZA
dc.identifier.vancouvercitation Fairweather T, Glazer J, Leslie R, de Decker M, Johnston S, Butterworth D. Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios. 2009 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18560 en_ZA
dc.identifier.ris TY - Working Paper AU - Fairweather, Tracey AU - Glazer, Jean AU - Leslie, Rob AU - de Decker, Michelle AU - Johnston, Susan AU - Butterworth, Doug AB - The checks carried out on the hake offshore trawl catch and effort data, which provide the basis to split the catches by species and to obtain GLM-standardised CPUE indices of abundance by species, have focused on two separate steps. The first was a re-extract of the data from the original files to check for possible errors in the earlier extracts (this applies to the subset of the data for which size composition information can be unambiguously extracted). The second step was to increase the proportion of the data utilised (and at the same time to check for possible selection biases in the existing sample) by assigning size composition to drags for which this information was not directly available, on the basis of the average for other vessels for which this was available for the area and time at which the fishing concerned took place. The first step revealed a problem with extractions over the last few years which at times for certain vessels had linked the accumulated catch for the day with only the effort for the last trawl of the day, rather than for all trawls that day combined. DA - 2009 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2009 T1 - Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios TI - Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios UR - http://hdl.handle.net/11427/18560 ER - en_ZA


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