An assessment of inland fisheries in South Africa using fisheries-dependent and fisheries-independent data sources
- Authors: McCafferty, James Ross
- Date: 2012
- Subjects: Fisheries -- South Africa , Fishery management -- South Africa , Fisheries -- Economic aspects -- South Africa , Food security -- South Africa , Poverty -- South Africa , Economic development -- South Africa , Fishing -- South Africa , Fisheries -- Catch effort -- South Africa , Fish stock assessment -- South Africa , Fish populations -- South Africa , Linear models (Statistics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5229 , http://hdl.handle.net/10962/d1005072 , Fisheries -- South Africa , Fishery management -- South Africa , Fisheries -- Economic aspects -- South Africa , Food security -- South Africa , Poverty -- South Africa , Economic development -- South Africa , Fishing -- South Africa , Fisheries -- Catch effort -- South Africa , Fish stock assessment -- South Africa , Fish populations -- South Africa , Linear models (Statistics)
- Description: The role of inland fisheries as contributors to local and national economies in developing African countries is well documented. In South Africa, there is increasing interest in inland fisheries as vehicles for achieving national policy objectives including food security, livelihoods provision, poverty alleviation and economic development but there is surprisingly little literature on the history, current status, and potential of inland fishery resources. This lack of knowledge constrains the development of management strategies for ensuring the biological sustainability of these resources and the economic and social sustainability of the people that are dependent on them. In order to contribute to the knowledge base of inland fisheries in South Africa this thesis: (1) presents an exhaustive review of the available literature on inland fisheries in South Africa; (2) describes the organisation of recreational anglers (the primary users of the resource); (3) compiles recreational angling catch records and scientific gill net survey data, and assesses the applicability of these data for providing estimates of fish abundance (catch-per-unit effort [CPUE]); and finally, (4) determines the potential for models of fish abundance using morphometric, edaphic, and climatic factors. The literature review highlighted the data-poor nature of South African inland fisheries. In particular information on harvest rates was lacking. A lack of knowledge regarding different inland fishery sectors, governance systems, and potential user conflicts was also found. Recreational anglers were identified as the dominant user group and catch data from this sector were identified as potential sources of fish abundance and harvest information. Formal freshwater recreational angling in South Africa is a highly organised, multi-faceted activity which is based primarily on angling for non-native species, particularly common carp Cyprinus carpio and largemouth bass Micropterus salmoides. Bank anglers constituted the largest number of formal participants (5 309 anglers affiliated to formal angling organisations) followed by bass anglers (1 184 anglers affiliated to formal angling organisations). The highly structured nature of organised recreational angling and dominant utilisation of inland fisheries resources by this sector illustrated not only the vested interest of anglers in the management and development of inland fisheries but also the role that anglers may play in future decision-making and monitoring through the dissemination of catch data from organised angling events. Generalised linear models (GLMs) and generalised additive models (GAMs) were used to standardise CPUE estimates from bass- and bank angling catch records, which provided the most suitable data, and to determine environmental variables which most influenced capture probabilities and CPUE. Capture probabilities and CPUE for bass were influenced primarily by altitude and conductivity and multiple regression analysis revealed that predictive models incorporating altitude, conductivity, surface area and capacity explained significant (p<0.05) amounts of variability in CPUE (53%), probability of capture (49%) and probability of limit bag (74%). Bank angling CPUE was influenced by conductivity, surface area and rainfall although an insignificant (p>0.05) amount of variability (63%) was explained by a predictive model incorporating these variables as investigations were constrained by small sample sizes and aggregated catch information. Scientific survey data provided multi-species information and highlighted the high proportion of non-native fish species in Eastern Cape impoundments. Gillnet catches were influenced primarily by species composition and were less subject to fluctuations induced by environmental factors. Overall standardised gillnet CPUE was influenced by surface area, conductivity and age of impoundment. Although the model fit was not significant at the p<0.05 level, 23% of the variability in the data was explained by a predictive model incorporating these variables. The presence of species which could be effectively targeted by gillnets was hypothesised to represent the most important factor influencing catch rates. Investigation of factors influencing CPUE in impoundments dominated by Clarias gariepinus and native cyprinids indicated that warmer, younger impoundments and smaller, colder impoundments produced higher catches of C. gariepinus and native cyprinids respectively. A predictive model for C. gariepinus abundance explained a significant amount of variability (77%) in CPUE although the small sample size of impoundments suggests that predictions from this model may not be robust. CPUE of native cyprinids was influenced primarily by the presence of Labeo umbratus and constrained by small sample size of impoundments and the model did not adequately explain the variability in the data (r² = 0.31, p>0.05). These results indicate that angling catch- and scientific survey data can be useful in providing predictions of fish abundance that are biologically realistic. However, more data over a greater spatial scale would allow for more robust predictions of catch rates. This could be achieved through increased monitoring of existing resource users, the creation of a centralised database for catch records from angling competitions, and increased scientific surveys of South African impoundments conducted by a dedicated governmental function.
- Full Text:
- Date Issued: 2012
- Authors: McCafferty, James Ross
- Date: 2012
- Subjects: Fisheries -- South Africa , Fishery management -- South Africa , Fisheries -- Economic aspects -- South Africa , Food security -- South Africa , Poverty -- South Africa , Economic development -- South Africa , Fishing -- South Africa , Fisheries -- Catch effort -- South Africa , Fish stock assessment -- South Africa , Fish populations -- South Africa , Linear models (Statistics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5229 , http://hdl.handle.net/10962/d1005072 , Fisheries -- South Africa , Fishery management -- South Africa , Fisheries -- Economic aspects -- South Africa , Food security -- South Africa , Poverty -- South Africa , Economic development -- South Africa , Fishing -- South Africa , Fisheries -- Catch effort -- South Africa , Fish stock assessment -- South Africa , Fish populations -- South Africa , Linear models (Statistics)
- Description: The role of inland fisheries as contributors to local and national economies in developing African countries is well documented. In South Africa, there is increasing interest in inland fisheries as vehicles for achieving national policy objectives including food security, livelihoods provision, poverty alleviation and economic development but there is surprisingly little literature on the history, current status, and potential of inland fishery resources. This lack of knowledge constrains the development of management strategies for ensuring the biological sustainability of these resources and the economic and social sustainability of the people that are dependent on them. In order to contribute to the knowledge base of inland fisheries in South Africa this thesis: (1) presents an exhaustive review of the available literature on inland fisheries in South Africa; (2) describes the organisation of recreational anglers (the primary users of the resource); (3) compiles recreational angling catch records and scientific gill net survey data, and assesses the applicability of these data for providing estimates of fish abundance (catch-per-unit effort [CPUE]); and finally, (4) determines the potential for models of fish abundance using morphometric, edaphic, and climatic factors. The literature review highlighted the data-poor nature of South African inland fisheries. In particular information on harvest rates was lacking. A lack of knowledge regarding different inland fishery sectors, governance systems, and potential user conflicts was also found. Recreational anglers were identified as the dominant user group and catch data from this sector were identified as potential sources of fish abundance and harvest information. Formal freshwater recreational angling in South Africa is a highly organised, multi-faceted activity which is based primarily on angling for non-native species, particularly common carp Cyprinus carpio and largemouth bass Micropterus salmoides. Bank anglers constituted the largest number of formal participants (5 309 anglers affiliated to formal angling organisations) followed by bass anglers (1 184 anglers affiliated to formal angling organisations). The highly structured nature of organised recreational angling and dominant utilisation of inland fisheries resources by this sector illustrated not only the vested interest of anglers in the management and development of inland fisheries but also the role that anglers may play in future decision-making and monitoring through the dissemination of catch data from organised angling events. Generalised linear models (GLMs) and generalised additive models (GAMs) were used to standardise CPUE estimates from bass- and bank angling catch records, which provided the most suitable data, and to determine environmental variables which most influenced capture probabilities and CPUE. Capture probabilities and CPUE for bass were influenced primarily by altitude and conductivity and multiple regression analysis revealed that predictive models incorporating altitude, conductivity, surface area and capacity explained significant (p<0.05) amounts of variability in CPUE (53%), probability of capture (49%) and probability of limit bag (74%). Bank angling CPUE was influenced by conductivity, surface area and rainfall although an insignificant (p>0.05) amount of variability (63%) was explained by a predictive model incorporating these variables as investigations were constrained by small sample sizes and aggregated catch information. Scientific survey data provided multi-species information and highlighted the high proportion of non-native fish species in Eastern Cape impoundments. Gillnet catches were influenced primarily by species composition and were less subject to fluctuations induced by environmental factors. Overall standardised gillnet CPUE was influenced by surface area, conductivity and age of impoundment. Although the model fit was not significant at the p<0.05 level, 23% of the variability in the data was explained by a predictive model incorporating these variables. The presence of species which could be effectively targeted by gillnets was hypothesised to represent the most important factor influencing catch rates. Investigation of factors influencing CPUE in impoundments dominated by Clarias gariepinus and native cyprinids indicated that warmer, younger impoundments and smaller, colder impoundments produced higher catches of C. gariepinus and native cyprinids respectively. A predictive model for C. gariepinus abundance explained a significant amount of variability (77%) in CPUE although the small sample size of impoundments suggests that predictions from this model may not be robust. CPUE of native cyprinids was influenced primarily by the presence of Labeo umbratus and constrained by small sample size of impoundments and the model did not adequately explain the variability in the data (r² = 0.31, p>0.05). These results indicate that angling catch- and scientific survey data can be useful in providing predictions of fish abundance that are biologically realistic. However, more data over a greater spatial scale would allow for more robust predictions of catch rates. This could be achieved through increased monitoring of existing resource users, the creation of a centralised database for catch records from angling competitions, and increased scientific surveys of South African impoundments conducted by a dedicated governmental function.
- Full Text:
- Date Issued: 2012
The role of the teachers' centre in the professional development and in-service training of teachers with specific reference to the East London Teachers' Centre
- Authors: Badenhorst, John Henry
- Date: 1992
- Subjects: Teachers -- In-service training -- South Africa , Education -- South Africa -- East London , Professional education -- South Africa , Educational change -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1755 , http://hdl.handle.net/10962/d1003639 , Teachers -- In-service training -- South Africa , Education -- South Africa -- East London , Professional education -- South Africa , Educational change -- South Africa
- Description: Teachers' Centres are one of the means whereby teachers needs for in-service education and training (Inset) can be met. The professional basis of Teachers' Centres as providers of in-service education and training derives from the need of teachers to develop professionally throughout their careers. Aspects which need to be considered are the need for professional growth and the professional nature of teaching. The effective provision of in-service training requires a knowledge of effective in-service training practise and the barriers that could be encountered in presenting it. Central to any Inset for teachers would be the teachers' needs for such activity. Following on a general statement of teachers needs for Inset the role of the Teachers' Centre in meeting these needs will be examined. Teachers' Centres have specific advantages in meeting certain areas of need for Inset by teachers. A knowledge of the professional activities of teachers activity and methods of establishing the needs for Inset of teachers should promote the effective provision of these programmes. The teacher as an adult learner is important to effective Teachers' Centre operation and the nature of adult learning and variables which affect it will determine the Teachers' Centre reaction in providing Inset. Subject study group activity is very important in Teachers' Centres in the Cape Province and the principles involved in their operation together with practical considerations regarding their operation are important in the provision of Inset. The practical application of theory is illustrated by examples from the East London Teachers' Centre with an emphasis on organisation and the creation of a climate within the Centre for the existence of study groups. The presentation methods used in these study group activities are important and will vary according to the needs of the study group. The selection of methods together with the organisation of presentations and practical methods used in presentation will have an important effect on how they operate. Teachers' Centres have a role to play in promoting change and innovation in schools. The theories of promoting innovation and the roles of the change agent are important. Practical examples from the East London Teachers' Centre are provided. This research, thus, provides a theoretical study of the role of Teachers' Centres in meeting some of the inset needs of teachers as well as practical examples of such activities.
- Full Text:
- Date Issued: 1992
- Authors: Badenhorst, John Henry
- Date: 1992
- Subjects: Teachers -- In-service training -- South Africa , Education -- South Africa -- East London , Professional education -- South Africa , Educational change -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1755 , http://hdl.handle.net/10962/d1003639 , Teachers -- In-service training -- South Africa , Education -- South Africa -- East London , Professional education -- South Africa , Educational change -- South Africa
- Description: Teachers' Centres are one of the means whereby teachers needs for in-service education and training (Inset) can be met. The professional basis of Teachers' Centres as providers of in-service education and training derives from the need of teachers to develop professionally throughout their careers. Aspects which need to be considered are the need for professional growth and the professional nature of teaching. The effective provision of in-service training requires a knowledge of effective in-service training practise and the barriers that could be encountered in presenting it. Central to any Inset for teachers would be the teachers' needs for such activity. Following on a general statement of teachers needs for Inset the role of the Teachers' Centre in meeting these needs will be examined. Teachers' Centres have specific advantages in meeting certain areas of need for Inset by teachers. A knowledge of the professional activities of teachers activity and methods of establishing the needs for Inset of teachers should promote the effective provision of these programmes. The teacher as an adult learner is important to effective Teachers' Centre operation and the nature of adult learning and variables which affect it will determine the Teachers' Centre reaction in providing Inset. Subject study group activity is very important in Teachers' Centres in the Cape Province and the principles involved in their operation together with practical considerations regarding their operation are important in the provision of Inset. The practical application of theory is illustrated by examples from the East London Teachers' Centre with an emphasis on organisation and the creation of a climate within the Centre for the existence of study groups. The presentation methods used in these study group activities are important and will vary according to the needs of the study group. The selection of methods together with the organisation of presentations and practical methods used in presentation will have an important effect on how they operate. Teachers' Centres have a role to play in promoting change and innovation in schools. The theories of promoting innovation and the roles of the change agent are important. Practical examples from the East London Teachers' Centre are provided. This research, thus, provides a theoretical study of the role of Teachers' Centres in meeting some of the inset needs of teachers as well as practical examples of such activities.
- Full Text:
- Date Issued: 1992
An investigation of certain complex ions of trivalent chromium by spectrophotometric and other physical methods
- Authors: Burley, Ralph Walter
- Date: 1950
- Subjects: Chromium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4521 , http://hdl.handle.net/10962/d1014675
- Description: Although chromium coordination compounds are of considerable technological importance, they have been subjected to few thorough investigations since Werner's original experlments, in spite of the fact that we now possess a number of accurate physical methods, not available in Werner's time for the study of coordination complexes, The object of the work described in this thesis was to obtain further information on the chemistry of complex chromium(III) ions with special reference to the dioxalato-diaquochromiate system, [Cr(C₂0₄)₂(H₂0)₂]. For this purpose; spectrophotometric and potentlometrlc measurements were combined to yield information on a number of topics, The spectrophotometric investigations consisted in measuring the absorption spectra of the potassium salts of the complexes under consideration and in observing the changes in light absorption which occur during their formatlon and decomposition. The instrument used was a Beckmann Quartz Spectrophotometer model du. More than than twelve new absorption spectra were measured in this work and in conjunction with the spectra of other chromium and cobalt complexes reported by earlier workers, these are used to review the position of spectrophotometry as a method of investigating chromium complexes. The reasons for the shapes of the absorption spectra are discussed and it is concluded that spectrophotometry is useful for observing the progress of reactions involving complex ions and for analysing solutions, but that more fundamental data cannot be expected from the absorption curves.
- Full Text:
- Date Issued: 1950
- Authors: Burley, Ralph Walter
- Date: 1950
- Subjects: Chromium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4521 , http://hdl.handle.net/10962/d1014675
- Description: Although chromium coordination compounds are of considerable technological importance, they have been subjected to few thorough investigations since Werner's original experlments, in spite of the fact that we now possess a number of accurate physical methods, not available in Werner's time for the study of coordination complexes, The object of the work described in this thesis was to obtain further information on the chemistry of complex chromium(III) ions with special reference to the dioxalato-diaquochromiate system, [Cr(C₂0₄)₂(H₂0)₂]. For this purpose; spectrophotometric and potentlometrlc measurements were combined to yield information on a number of topics, The spectrophotometric investigations consisted in measuring the absorption spectra of the potassium salts of the complexes under consideration and in observing the changes in light absorption which occur during their formatlon and decomposition. The instrument used was a Beckmann Quartz Spectrophotometer model du. More than than twelve new absorption spectra were measured in this work and in conjunction with the spectra of other chromium and cobalt complexes reported by earlier workers, these are used to review the position of spectrophotometry as a method of investigating chromium complexes. The reasons for the shapes of the absorption spectra are discussed and it is concluded that spectrophotometry is useful for observing the progress of reactions involving complex ions and for analysing solutions, but that more fundamental data cannot be expected from the absorption curves.
- Full Text:
- Date Issued: 1950
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