Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal

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dc.contributor.advisorAttwood, Colinen_ZA
dc.contributor.authorLabinjoh, Lisaen_ZA
dc.date.accessioned2015-07-03T08:35:07Z
dc.date.available2015-07-03T08:35:07Z
dc.date.issued2014en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractThis study estimates rates of shark depredation in the charter boat fishery on Protea Banks, KwaZulu-Natal. Previous estimates based on fisher surveys suggested that shark depredation is a concern locally and may distort fishing mortality estimates. Methods involved quantitative data collection by an onboard observer from November 2013 to January 2014. Catch composition data were collected to enable comparisons with the commercial and recreational catch returns used in monitoring and assessment. Results revealed an average depredation rate of 8.4% that varied depending on the species fishers targeted. Depredation was highest when catching pelagic species (18.6%) and lowest when catching reef species (1.9%). Depredation rates were highest in November (19.6%) and lowest in January (5.3%). Observed rates were highest on the Banks itself and immediately offshore (9.9%), but no depredation was observed inshore of the Banks. The most commonly identified sharks involved in depredation incidents were the dusky shark (Carcharhinus obscurus) and the blacktip shark (Carcharhinus limbatus). Multi-dimensional scaling showed commercial catch composition to be significantly different from recreational and charter catch composition, mainly due to abundance of tuna in the recreational and charter sectors. No significant relationship was found between catch composition and shark depredation. Depredation is estimated to cost charter fishing operators 8% of their revenue. Depredation rates are at a level that could impact effective stock assessment and should be considered when making management decisions.en_ZA
dc.identifier.apacitationLabinjoh, L. (2014). <i>Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/13359en_ZA
dc.identifier.chicagocitationLabinjoh, Lisa. <i>"Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2014. http://hdl.handle.net/11427/13359en_ZA
dc.identifier.citationLabinjoh, L. 2014. Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Labinjoh, Lisa AB - This study estimates rates of shark depredation in the charter boat fishery on Protea Banks, KwaZulu-Natal. Previous estimates based on fisher surveys suggested that shark depredation is a concern locally and may distort fishing mortality estimates. Methods involved quantitative data collection by an onboard observer from November 2013 to January 2014. Catch composition data were collected to enable comparisons with the commercial and recreational catch returns used in monitoring and assessment. Results revealed an average depredation rate of 8.4% that varied depending on the species fishers targeted. Depredation was highest when catching pelagic species (18.6%) and lowest when catching reef species (1.9%). Depredation rates were highest in November (19.6%) and lowest in January (5.3%). Observed rates were highest on the Banks itself and immediately offshore (9.9%), but no depredation was observed inshore of the Banks. The most commonly identified sharks involved in depredation incidents were the dusky shark (Carcharhinus obscurus) and the blacktip shark (Carcharhinus limbatus). Multi-dimensional scaling showed commercial catch composition to be significantly different from recreational and charter catch composition, mainly due to abundance of tuna in the recreational and charter sectors. No significant relationship was found between catch composition and shark depredation. Depredation is estimated to cost charter fishing operators 8% of their revenue. Depredation rates are at a level that could impact effective stock assessment and should be considered when making management decisions. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal TI - Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal UR - http://hdl.handle.net/11427/13359 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/13359
dc.identifier.vancouvercitationLabinjoh L. Rates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natal. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/13359en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherApplied Marine Scienceen_ZA
dc.titleRates of shark depredation of line-caught fish on the Protea Banks, KwaZulu-Natalen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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