Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca²⁺ mobilising messenger in mammalian and non-mammalian cells. Studies on a variety of cell types suggest that NAADP evokes Ca²⁺ release from a lysosome-related store and via activation of a receptor distinct from either ryanodine receptors (RyR) or inositol 1,4,5-trisphosphate (IP₃) receptors (IP₃R). However, the identity of the NAADP receptor has, until now, remained elusive. In this thesis I have shown that NAADP-evoked Ca²⁺ release from lysosomes is underpinned by two-pore channels (TPCs), of which there are 3 subtypes, TPC1, TPC2 and TPC3. When stably over-expressed in HEK293 cells, TPC2 was found to be specifically targeted to lysosomes, while TPC1 and TPC3 were targeted to endosomes. Initial Ca²⁺ signals via TPC2, but not those via TPC1, were amplified into global Ca²⁺ waves by Ca²⁺-induced Ca²⁺ release (CICR) from the endoplasmic reticulum (ER) via IP₃Rs. I have shown that, consistent with a role for TPCs in NAADP-mediated Ca²⁺ release, TPC2 is expressed in pulmonary arterial smooth muscle cells (PASMCs), is likely targeted to lysosomal membranes, and that TPCs also underpin NAADP-evoked Ca²⁺ signalling in this cell type. However, and in contrast to HEK293 cells, in PASMCs NAADP evokes spatially restricted Ca²⁺ bursts that are amplified into global Ca²⁺ waves by CICR from the sarcoplasmic reticulum (SR) via a subpopulation of RyRs, but not via IP₃Rs. I have demonstrated that lysosomes preferentially co-localise with RyR subtype 3 (RyR3) in the perinuclear region of PASMCs to comprise a “trigger zone” for Ca²⁺ signalling by NAADP, away from which a propagating Ca²⁺ wave may be carried by subsequent recruitment of RyR2. The identification of TPCs as a family of NAADP receptors may further our understanding of the mechanisms that confer the versatility of Ca²⁺ signalling which is required to regulate such diverse cellular functions as gene expression, fertilization, cell growth, and ultimately cell death.

This thesis presents several problems based on papers written jointly by the author and Dr. Christian-Oliver Ewald. Firstly, the author extends the model presented by Fershtman and Nitzan (1991), which studies a deterministic differential public good game. Two types of volatility are considered. In the first case the volatility of the diffusion term is dependent on the current level of public good, while in the second case the volatility is dependent on the current rate of public good provision by the agents. The result in the latter case is qualitatively different from the first one. These results are discussed in detail, along with numerical examples. Secondly, two existing lines of research in game theoretic studies of fisheries are combined and extended. The first line of research is the inclusion of the aspect of predation and the consideration of multi-species fisheries within classical game theoretic fishery models. The second line of research includes continuous time and uncertainty. This thesis considers a two species fishery game and compares the results of this with several cases. Thirdly, a model of a fishery is developed in which the dynamic of the unharvested fish population is given by the stochastic logistic growth equation and it is assumed that the fishery harvests the fish population following a constant effort strategy. Explicit formulas for optimal fishing effort are derived in problems considered and the effects of uncertainty, risk aversion and mean reversion speed on fishing efforts are investigated. Fourthly, a Dixit and Pindyck type irreversible investment problem in continuous time is solved, using the assumption that the project value follows a Cox-Ingersoll- Ross process. This solution differs from the two classical cases of geometric Brownian motion and geometric mean reversion and these differences are examined. The aim is to find the optimal stopping time, which can be applied to the problem of extracting resources.

In an attempt to address the seeming imbalance within studies of rural communities in Australia linked to primary industries, this study examines the broader aspects of policy changes and bio-economic imperatives in the Western Rock Lobster Fishery and the effects of the restructuring of the fishery on communities that host the rock lobster fleet. It is an innovative study in that it is one of the first comprehensive studies of industry restructuring in the fisheries sector; a study of the linkages and implications of restructuring on the social, economic and cultural facets of coastal communities in Western Australia. Globalisation in the fishery sector, aided by technological advances, has resulted in a greater exploitation of high-value fisheries for export. Intensified globalisation has also brought about environmental and social standards that ensure the survival of by-catch species and promote responsible codes of fishing practice. In Australia, the active support of the government for globalisation, led to the adoption of export-oriented policies emphasising competitiveness and efficiency. Consideration of market principles thus govern fisheries regulators when deciding on the management arrangements to adopt for a particular fishery. In considering a number of policy instruments and management measures, government regulators also consider the conservation of marine resources alongside the production of significant economic and social benefits. The Western Rock Lobster Fishery is the most valuable single species fishery in Western Australia with a sizeable financial and employment contribution to coastal communities along the Western Australian coast. Any management scheme adopted for this fishery, as such, not only has to take into account biological and environmental imperatives but also economic and social objectives. The analysis of the fishery undertaken in this thesis underlines the need for a holistic view of fishery management that takes into consideration not only biological sustainability, but also promotes an understanding of fishers' behaviours and fishing patterns and the consequent effects on specific communities. The demographic and social changes that affect rural communities further complicate the economic restructuring at the fishery level, with fishers' responses differing based on their circumstances and preferences. This thesis presents a snapshot of a fishery deliberating changes in management arrangements and its effects on coastal communities whose socio-demographic and economic development historically has depended, and to a great extent is still dependent, upon rock lobster fishing. It provides empirical evidence that lends support to the view that the pro-market policies promoting competition and entrepreneurialism have resulted in a spatially uneven development in regional Australia. Specific localities can deal with the changes brought about by globalisation and policy change. However, the manner in which these communities deal and cope with these changes depends on a number of factors, among others, the level of diversification of the local economy, demographic and social structures, and other factors such as the level of resilience and the social capital base within the community.

Doctorat en sciences sociales, politiques et économiques / info:eu-repo/semantics/nonPublished

Tuna are of significant global economic importance and a prime food source. Increased levels of fishing have resulted in many stocks being under threat and a number of species are considered to be overfished. The South African tuna industry has had limited management attention from the South African fisheries management agency. A recent development has been an increase in the number of tuna caught by small vessels that target the fresh tuna market in South Africa and overseas. This has highlighted the importance of developing a holistic management plan for the sector and creating an awareness, among vessel owners, of the importance of compliance with initiatives such as the Marine Stewardship Council (MSC). The South African tuna fishery comprises three sectors: baitboat, sport and longline, all of which are currently in need of acquiring more biological and fisheries data. This project was initiated to collate existing information and to collect additional information where possible. This encompassed a qualitative and quantitative assessment of the size and shape of the tuna fishing industry, which included estimates of total catch, effort, catch-per-unit-of-effort (CPUE) and stock structure (obtained through comparative estimates of age and growth), as well as socio-economic and economic information. A technique involving an examination of specific vertebrae was used to obtain age-growth information for T. albacares. These data were used to estimate von Bertalanffy (VBGF) growth parameters: F 2 1. , k 0.1 , and t₀ -0. 1 year. No significant differences in growth parameters were found in yellowfin tuna (Thunnus albacares) from different localities around the South African coast, i.e. from the south eastern Atlantic and the south western Indian Ocean. In addition, growth did not differ between South Africa and other regions (Draganic and Pelzcarski 1984, Fonteneau 1980, Gascuel et al. 1992, LeGuen and Sakagawa 1973, Lehodey and Leroy 1999, Lessa and Duarte-Neto 2004, Shuford et al. 2007, Stequert et al. 1996, Wild 1986, Yang et al. 1969). Further substantiation of the above-mentioned observations was found by recording differences in the sizes of fish caught in the inshore (baitboat and sport fishery vessels) and offshore (large pelagic longline vessels) sectors of South African tuna fisheries. A significant difference between the regions — in terms of the size of fish caught inshore — was noted, with mostly-juvenile fish being caught in KwaZulu-Natal (5.4 ± 3.5kg), sub-adult fish in the Eastern Cape (26.2 ± 13.4kg), and adult fish in the Western Cape (42.3 ± 14.4kg). Since mostly-adult fish were caught offshore by longliners, with no significant differences between regions, it is however possible th at adult fish predominantly inhabit the offshore region. Yellowfin tuna caught by the large pelagic longline fishery in the three managerial zones (A, B and C) were predominantly adult fish of similar size, namely Zone A: 38.9 ± 6.9kg; Zone B: 28.7 ± 4.6kg, and Zone C: 36.0 ± 5.1kg. The recreational ski boat sport fishery has remained stable, in terms of participation, consisting mostly of white middle aged males in the top 25% of household income distribution, having either permanent occupational status or being retired. Fishers within this sector are willing to incur great expense to partake in the fishery and they provide an important economic contribution to coastal towns, particularly in the Eastern Cape. The total catch (of 83t) of yellowfin tuna by the competitive sport fishery within the Western and Eastern Cape regions was considerably lower than that of commercial tuna baitboat catches, which amounted to 186t, and the large pelagic longline sector that caught t in 200. It is however likely that the competitive sport fishery's total yellowfin tuna catch (of 83t in 2009) of the Eastern and Western Cape competitive sport fishery was considerably less than the total yellowfin tuna catches of the whole South African deep-sea sport fishery. Longfin tuna are the primary target species of South Africa‘s baitboat fisheries, comprising an average of 86% of the total catch and generating ZAR49 million in employment income in 2002. South Africa was responsible for 20% of the total longfin tuna annual yield in 2004 in the southern Atlantic Ocean, behind Taiwan with 59%. However, yellowfin tuna only contributes a small percentage towards total catches (8.4 ± 8.2% between 1995 and 2009), generating ZAR1.3 million in employment income in 2002. Of the four vessel categories comprising the tuna baitboat fishery, ski boats had the highest yellowfin tuna CPUE in 2009 (117 ± 62 kg.vessel⁻¹.day⁻¹) and the lowest effort. The ski boats sector is the most opportunistic fishery as they are only active when either longfin or yellowfin tuna are in high abundance. At such times catches are guaranteed, so can be expected to offset expenses. In 2009 the CPUE for yellowfin tuna for 15–19m vessels and freezer deckboats was 12 ± 20kg.vessel⁻¹.day⁻¹ and 3 ± 6kg.vessel⁻¹.day⁻¹, respectively. These vessels specifically target longfin tuna when they are in abundance. Since the start of the tuna baitboat fishery in 1995, there has been a substantial increase in the number of new entrants. In 2002 this sector had a fleet size of 82 vessels with a capital value of ZAR163 million and a total employment income of ZAR58 million, employing 2 173 fishers, of which 87% were black African. The commercial tuna baitboat fleet has subsequently grown to 200 vessels and 3600 crew, with 110 active vessels fishing for a combined fleet average of 46 days per year. There are a high number of owner-operated vessels. Since 2007 the fishery's profit to cost ratio has been low due to the low abundance of tuna stocks off the coast of South Africa, which has resulted in poor catch returns, placing economic pressure on the fishery. The baitboat industry is a low-profit-margin fishery with a total net catch value worth ZAR90 million in 2009 (Feike 2010). The abundance of yellowfin tuna influences profit margins, with very high profits being made when abundance and catches are high. The large pelagic longline fishery has a total allowable effort of 43 vessels of which only 30 vessels fished during 2009, when a reported 766t of yellowfin tuna were caught, representing a total tonnage far in excess of that obtained by the combined effort of the baitboat and sport fishery. It is, however, assumed that considerable underreporting of catches takes place within this fishery, which means that the estimated total net catch value of ZAR100 million could, in fact, be much higher. Such underreporting of catches is of great concern for this fishery, as is the high bycatch of Chondricthians spp. that significantly outweighs imposed regulatory limits (DEAT 2007). The present study demonstrates the current lack of comprehensive catch and effort data for the sport, baitboat and longline fisheries as well as the serious limitations and flaws associated with current databases. Results from the present study have drawn attention to a number of high-priority research needs, as outlined below. (1) A major lack of comprehensive catch and effort data for the sport fishery, which can be rectified by focussing on obtaining more competition data, as well as high-quality catch and effort and socio-economic information, as opposed to relying on information from non-club anglers (Gartside et al. 1999, Williams 2003, Cass-Calay 2008). Acquisition of such data is relatively inexpensive: the location of organized clubs and their frequent competition meetings provide widespread coverage along the Southern African coastline. Such data acquisition efforts have the potential to provide reliable information on spatial catch trends. (2) Validation of vessel catch return data is required for commercial fisheries and on some recent data that has emerged from studies of catch rates and trends for target species, particularly in the longline fishery. In this context it should be noted that the most recent peer-reviewed publications on this exploratory fishery were published more than a decade ago (Kroese 1999, Penny and Griffiths 1999). Additional studies need to be undertaken and journal articles published on the current stock status of South African catches of yellowfin and bigeye tuna and swordfish.

Thesis (MBA (Business Management))--University of Stellenbosch, 2008. / AFRIKAANSE OPSOMMING: Verskeie korporatiewe fiaskos gedurende die afgelope dekade het wêreldwye opskudding veroorsaak met die gevolg dat daar vanaf ‘n nuwe oogpunt gekyk word na die wyses waarop korporasies bestuur word. Terselfdertyd is daar ‘n wêreldwye belangstelling gekweek in volhoubare ontwikkeling en korporasies se bydrae daartoe. Dit, tesame met korporatiewe bestuur, het tot die gevolg gehad dat die fokus vanaf die tradisionele finansiële verslaggewing geskuif het na rapportering op die sogenaamde “Tripple Bottom Line” en meer en meer maatskappye oor die wêreld genereer en publiseer deesdae op hul ekonomies-, maatskaplike-, omgewingsverantwoordelikhede en prestasies. Gou is daar egter besef dat rapportering en die opstel van beleide self nie genoeg is nie en een van die die grootste uitdagings aan korporatiewe bestuurders tans is om te verseker dat hul korporatiewe bestuurstelsels hul volhoubare strategieë ondersteun om te verseker dat die strategieë in hul maatskappystelsels en prosesse geintegreer is. Kaplan en Norton het in 1992 die Gebalanseerde Telkaart ontwikkel. Die telkaart is as instrument voorgestel om strategieë in aksie oor te skakel. Die telkaart erken dat die tradisionele finansiële maatstawwe nie voldoende is om die volhoudbare sukses van die maatskappy te verseker nie en skep ‘n balans tussen nie-tradisionele maatstawwe oor vier areas: finansieël, kliënte, interne prosesse en leer en groei. Alhoewel daar verskeie gevallestudies in literatuur voorkom waar Gebalanseerde Telkaart implementering gefaal het, het navorsing bewys dat in gevalle waar dit wel suksesvol geimplementeer is, die telkaart ‘n dramatiese verskil aan die maatskapy se prestasie gemaak het. Daar moet dus besef word dat die telkaart wel sy tekortkominge het en dat die implementering daarvan oordeelkundig moet geskied. Gedurende die 21st eeu het outeurs die potensiaal van die Gebalanseerde Telkaart om korporatiewe volhoudbaarheidsstrategië in aksie oor te skakel raakgesien om sodoende die gaping tussen volhoudbare korporatiewe bestuur en die integrasie van beleid en strategieë in die maatskappy prosesse en -stelsels te oorbrug met die integrasie van volhoudbare maatstawwe in die Gebalanseerde Telkaart. Wêreldwyd is die visvangbedryf gedurig onder die kollig vanweë sy impak op die omgewing en die Suid-Afrikaanse visvangbedryf word nie uitgesluit nie. Die visbedryf is ‘n bron afhanklike bedryf en maatskappye moet teen mekaar meeding vir toegang tot die ontgunning van die bron. Vanuit ‘n ekonomiese en ‘n omgewings oogpunt is dit dus van uiters belang dat maatskappye in die bedryf volhoudbare strategieë toepas om die hernubaarheid van die bron te verseker. Suid-Afrikaanse maatskappye bevind hulself egter in ‘n unieke situasie in terme van maatskaplike verantwoordelikheid vanweë die onregmatighede van die apartheidstelsel en maatskaplike verantwoordelikheid moet dus transformasie insluit. Daarvoor het die Departement van Handel en Industrie reeds Die Swart Ekonomiese Bemagtigings Telkaart ingestel om die vordering van maatskappye te meet. Hierdie telkaarte vorm dus ‘n uitstekende basis vir die volhoudbaarheids gebalanseerde integrasie, nie net om te voldoen aan die legislatiewe regulasies nie, maar ook om die geleenhede wat daaruit kan voortspruit ten volle te benut. Hierdie navorsingsverslag ondersoek dus die skakels tussen korporatiewe bestuur en korporatiewe volhoudbaarheid, die teorië rondom die Volhoudbaare Gebalanseerde Telkaart en die moontlike toepassing daarvan op die Suid-Afrikaanse visbedryf. / ENGLISH SUMMARY: Over the past decade outrageous corporate fiascos has resulted in a renewed interest in Corporate Governance and the way Corporates are managed. At the same time sustainable development and the Corporate contribution and Corporate sustainability has gathered worldwide interest in both institutional and corporate spheres. This has triggered new expectations for business transparency and has shifted the focus from traditional financial reporting to reporting on the organization’s impact and performance on the triple bottom line. More companies from across the globe are developing and reporting on their economic, social- and environmental responsibility and performance. It soon became clear that reporting on broad policy is simply not enough and one of the biggest challenges of corporate managers today are to ensure that their sustainable strategies and policies are integrated into their organizational governance structures and processes. Kapland and Norton have developed the Balanced Scorecard in 1992 to provide business managers with a management tool to translate their strategies into action. The scorecard recognizes that traditional financial measurements is not enough to ensure the continued success of organizations and creates a balance between non traditional measurements across four perspectives: financial, customers, internal processes and learning and growth. Although various case studies exist about Balanced Scorecard implementation, empirical research have indicated substantial performance improvement at organizations that have successfully implemented the Balanced Scorecard. Implementation thereof therefore has to be carried out with caution. During the 2000’s authors has recognized the potential of the Balanced Scorecard to translate Corporate sustainability strategies into action and bridge the gap between the way corporates are governed and sustainability by integrating sustainability measures into the Balanced Scorecard for the creation of the sustainability Balanced Scorecard. Fisheries, world wide are continually under the spotlight as a result of their impact on the environment and the South African fishing industry is certainly not excluded. Fisheries are a resource dependent industry and companies have to compete against each other for access to these resources. Apart from its environmental impact it is therefore of outmost importance that managers within the industry considers all the sustainability aspects in their organizational structures. This research report thus explores the link between Corporate Governance and Corporate Sustainability, the theory surrounding the sustainability Balanced Scorecard and the possible application thereof in order to ensure the long term sustainability of the industry.

This thesis presents a first analysis of how the South African fisheries authority (MCM) has utilised its fisheries management toolbox and governance framework in response to the emerging biological, economic and social challenges of post-apartheid fisheries in the Eastern Cape Province. Despite recognition of the socio-economic circumstances of traditional subsistence fishers in the region, the national fisheries management authority implemented a 'target resource orientated' management approach similar to that used for South Africa's rights-based commercial fisheries. Anecdotal evidence of entrenched illegal fishing for abalone, spiny lobster, and species targeted by subsistence fishers however suggested that MCM's management approach was encountering serious problems, as the needs and circumstances of inshore fishers and fishing communities were not adequately being understood and addressed. A review of fisheries management literature therefore shaped the hypothesis that an underlying governance problem was responsible for the symptoms of management failure being observed. In this regard, management is seen as more concerned with the technical and regulatory measures of the day-to-day operations of regulated fisheries, while fisheries governance needs to take account of "the sum of legal, social, economic and political arrangements used to manage fisheries ... ". Thus, governance includes policy making and management decision-making, with simultaneous recognition of issues outside of the fisheries sector. It thus appeared that the underlying problem was rather one of broader fisheries governance and inappropriate governance objectives with consequent inappropriate resource management arrangements. This thesis set out to gather evidence to test this hypothesis.

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.