Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa

dc.contributor.advisorField, John Gen_ZA
dc.contributor.advisorCrawford, RJMen_ZA
dc.contributor.advisorOosthuizen, WHen_ZA
dc.contributor.authorPillay, Pavitrayen_ZA
dc.date.accessioned2014-09-11T06:48:54Z
dc.date.available2014-09-11T06:48:54Z
dc.date.issued2002en_ZA
dc.descriptionBibliography : leaves 59-65.en_ZA
dc.description.abstractCompetition for pelagic fish resources was investigated by assessing the overlap in the food base of three land-based predators: Cape gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and humans operating via a purse-seine fishery. Multivariate analysis the diet composition of gannets and seals and the catch composition of the pelagic fishery indicated that there were three ""feeding regimes"" during the 21-year study period: (1978-1998), an anchovy-dominated regime (1978-1983), an intermediate regime (1984-1990) and a sardine-abundant regime (1991-1998). It further showed that anchovy (Engraulis capensis) and sardine (Sardinops sagax) contributed substantially to the catches of all three top predators. Analysis of size-distributions of catches showed that the three predators generally caught the same sizes of anchovy and sardine, reflecting very little resource partitioning. The analysis demonstrated stronger competition between gannets and the purse-seiners than between gannets and seats, especially during seasons of poor recruitment. Furthermore, seasonal differences in the catches of the three predators are related to the recruitment, growth and migration of the prey species. The study confirmed previous observations that gannets prefer sardine to anchovy by showing gannet exploitation of sardine in the early 19905, when anchovy was still abundant. The gannets, which are species-specific feeders, may be impacted by substantial removals of pelagic fish resources by a large seal population and a large fishery.en_ZA
dc.identifier.apacitationPillay, P. (2002). <i>Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/7422en_ZA
dc.identifier.chicagocitationPillay, Pavitray. <i>"Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2002. http://hdl.handle.net/11427/7422en_ZA
dc.identifier.citationPillay, P. 2002. Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Pillay, Pavitray AB - Competition for pelagic fish resources was investigated by assessing the overlap in the food base of three land-based predators: Cape gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and humans operating via a purse-seine fishery. Multivariate analysis the diet composition of gannets and seals and the catch composition of the pelagic fishery indicated that there were three ""feeding regimes"" during the 21-year study period: (1978-1998), an anchovy-dominated regime (1978-1983), an intermediate regime (1984-1990) and a sardine-abundant regime (1991-1998). It further showed that anchovy (Engraulis capensis) and sardine (Sardinops sagax) contributed substantially to the catches of all three top predators. Analysis of size-distributions of catches showed that the three predators generally caught the same sizes of anchovy and sardine, reflecting very little resource partitioning. The analysis demonstrated stronger competition between gannets and the purse-seiners than between gannets and seats, especially during seasons of poor recruitment. Furthermore, seasonal differences in the catches of the three predators are related to the recruitment, growth and migration of the prey species. The study confirmed previous observations that gannets prefer sardine to anchovy by showing gannet exploitation of sardine in the early 19905, when anchovy was still abundant. The gannets, which are species-specific feeders, may be impacted by substantial removals of pelagic fish resources by a large seal population and a large fishery. DA - 2002 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2002 T1 - Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa TI - Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa UR - http://hdl.handle.net/11427/7422 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/7422
dc.identifier.vancouvercitationPillay P. Competition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2002 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/7422en_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.otherZoologyen_ZA
dc.titleCompetition for anchovy (Engraulis capensis) and sardine (Sardinops sagax) between the Cape Gannet (Morus capensis), Cape fur seal (Arctocephalus pusillus pusillus) and the purse-seine fishery on the west coast of South Africaen_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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