Thesis (MComm)—Stellenbosch University, 2015. / ENGLISH ABSTRACT: The purpose of this study was to investigate the organisational and institutional arrangements for sustainable consumer-oriented community-based aquaculture in Hamburg, in the Eastern Cape, and Camdeboo and Saldanha Bay, both in the Western Cape. Without these factors the development of aquaculture will be impossible or unsustainable. The investigation will help in revealing whether markets exist or can be created, the required skills and investment, and the appropriate institutional arrangements. Two major research strategies were used, namely qualitative methods and case studies. The results revealed that, in all three case studies, the products were not exported and had different target markets and marketing objectives. There was a potential market for some of the products overseas. Leading pioneering firms, such as those that have developed the technologies for aquaculture, control the value chain by setting, monitoring and enforcing the parameters under which other value chain members operate. The results further showed that, in all three case studies, the beneficiaries had some of form of schooling; some had matric, while others had lower levels of education. In some scenarios, Adult Basic Education and Training (ABET) training was offered, which combines aquaculture and life skills. Furthermore, unlike with kob, farming of species such as mussel, oyster and catfish did not require such onerously high technical skills and monitoring of parameters. There is no real need for high levels of education in the farming of these three species and, in most cases, people with less than matric are trained in the various aspects of fish farming on the job. Aquaculture appears to be a very capital-intensive industry. Apart from the capital investments, operational expenses have to be incurred, even during the development phase. The absence of clear policy frameworks and legislation results in contradictory messages. Choosing the type of business ownership may depend on many factors such as financing, admin costs, tax implications, insolvency, business size and continuity. The implication of the results of this study for community-based aquaculture is that investment from the public sector and private sector is required, both in terms of capital infrastructure and operational costs. Communities should start with simpler forms of aquaculture, such as oyster and mussel farming. Kob farming, on the other hand, requires high technical skill. In all cases, the approaches initially require managerial, business and technical support and handholding for community empowerment groups. When the development is in its infancy, community-based aquaculture projects need to link and create distribution agencies that deal with marketing and distribution. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die organisatoriese en institusionele reëlings te ondersoek vir volhoubare verbruikersgerigte gemeenskapsgebaseerde akwakultuur in Hamburg, in die Oos-Kaap, en die Kamdeboo en Saldanhabaai, in die Wes-Kaap. Sonder hierdie faktore is die ontwikkeling van akwakultuur onmoontlik of nvolhoubaar. Die ondersoek sal help om te bepaal of markte bestaan of geskep kan word, en watter vaardighede, investering en institusionele reëlings vereis word. Twee groot navorsingstrategieë is gebruik, naamlik kwalitatiewe metodes en gevallestudies. Die resultate van al drie gevallestudies het getoon dat die produkte nie uitgevoer word nie en dat daar verskillende teikenmarkte en bemarkingsdoelwitte vir die produkte is. Vir van die produkte is daar ʼn potensiële oorsese mark. Toonaangewende maatskappye soos dié wat tegnologie vir akwakultuur ontwikkel het, beheer die waardeketting deur die opstel, monitering en handhawing van die parameters waarvolgens ander lede van die waardeketting funksioneer. Verder het die resultate getoon dat die begunstigdes in al drie gevallestudies een of ander vorm van skoolopleiding gehad het; sommige het matriek gehad terwyl ander laer vlakke van skoolopleiding voltooi het. In sommige gevalle is Adult Basic Education and Training(ABET)-opleiding aangebied, waar akwakultuur en lewensvaardighede gekombineer is. Verder, in teenstelling met die kabeljoubedryf, vereis die teelt van spesies soos mossels, oesters en babers nie sulke gespesialiseerde tegniese vaardighede en die noukeurige monitering van parameters nie. Daar is geen werklike behoefte vir hoë vlakke van onderwys vir boerdery met laasgenoemde drie spesies nie en in die meeste gevalle ondergaan mense met minder as matriek indiensopleiding in die verskillende aspekte van visboerdery. Verder blyk akwakultuur 'n kapitaalintensiewe bedryf te wees. Afgesien van die kapitale belegging moet operasionele uitgawes aangegaan word, selfs in die ontwikkelingsfase. Die afwesigheid van duidelike beleidsraamwerke en wetgewing gee aanleiding tot teenstrydige boodskappe. Die keuse van die soort onderneming kan afhang van baie faktore, wat finansiering, administratiewe koste, belastingimplikasies, insolvensie, ondernemingsgrootte en kontinuïteit insluit. Die implikasie van die resultate van hierdie studie vir gemeenskapsgebaseerde akwakultuur is dat hoë investering vereis word, beide in terme van kapitaalinfrastruktuur en bedryfskoste. Gemeenskappe moet eers met eenvoudiger vorme van akwakultuur, soos oester- en mosselboerdery, wegspring. Kabeljou, aan die ander kant, vereis hoë tegniese vaardigheid. In alle gevalle vereis die benaderings aanvanklike bestuurs-, besigheids- en tegniese ondersteuning en daadwerklike bystand vir gemeenskapsbemagtigingsgroepe. Terwyl die ontwikkeling in sy kinderskoene is, moet gemeenskapsgebaseerde akwakultuurprojekte verspreidingsagentskappe skep en met sulke agentskappe skakel om bemarking en verspreiding te hanteer.

Thesis (MPhil)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: This paper reviews the status of world aquaculture with a primary focus on Sub-Saharan and Chinese freshwater aquaculture, and proposes a commercial integrated farming model for implementation in rural areas in KwaZulu-Natal. The model combines the paradigms of age-old Chinese integrated pond farming principles with a commercial approach in the socio-economic context of Sub-Saharan Africa. The project's objective is to contribute to the alleviation of poverty through economic development in rural areas using environmentally and economically sustainable farming practices. The project's medium-term goal is to achieve the critical production volume to warrant vertical integration into a hatchery, feed mill and processing facility. Integration would reduce operating costs and afford better standards of basic services. The project's long-term goal is to grow and expand the model to make a contribution to global food security through distributing a fish-based, nutritionally balanced meal to famine relieve efforts in low-income food deficiency countries (LIFDC). The model proposes the development of individual farms each with a production capacity of 40 to 60 tons of fish per annum. The species available include tilapia, catfish, carp, mullet, bass and eels. The farms will each consist of eight grow-out fishponds totalling 4 hectares of water surface area, a basic homestead and 6 hectares for crops and livestock rearing. The farms are designed to utilize the nutrient rich effluent from the fishponds to flood-irrigate crops planted in the fields below. Through application of the principles of the integrated approach to fish-crops-livestock farming as applied by the Chinese over the last 2,000 years, the farms are designed in a way that nothing is wasted. The waste product from one system becomes input for the next system. The integrated approach is extremely cost effective and lends itself to total organic farming adhering to environmentally responsible and sustainable farming principles. Two hundred such farming units would produce a total of 8,000 to 12,000 ton per year that equates to double the current combined freshwater aquaculture production from all the SADC member countries. / AFRIKAANSE OPSOMMING: Die werkstuk bied 'n oorsig van akwakultuur in die wêreld, met 'n primêre fokus op die stand van varswater akwakultuur in Sub-Sahara en China. 'n Ontwikkelingsmodel vir geïntegreerde kommersiële boerdery word voorgestel, in die plattelandse dele van KwaZulu-Natal word woorhou. Die model koppel die konsepte van eeue-oue Chinese beginsels van geïntegreerde visboerdery met kommersiële winsgewendheid, binne die sosio-ekonomiese konsep van sub- Sahara Afrika. Die doel van die model is om 'n beduidende rol te speel in die verligting van armoede deur die ontwikkeling van ekonomiese aktiwiteit in plattelandse gebiede d.m.v. omgewings- en ekonomies volhoubare boerderypraktyke. Die projek se mediumtermyndoelwit is om die kritiese produksievolume te bereik wat vertikale integrasie met 'n visbroeiery, 'n voermeule en 'n prosesseringsfasiliteit sal regverdig. Dit saloperasionele kostes verminder en beter beheer verseker oor hierdie basiese insette. Die langtermyndoelwit is om die model uit te brei ten einde 'n bydrae te maak tot globale voedselvoorsiening deur die verspreiding van 'n voedsame, gebalanseerde maaltyd met vis as basis, as hongersnoodverligting in lae inkomste lande met 'n voedseltekort. Die model stel 'n reeks individuele plase voor, elk met 'n produksiekapasiteit van 40 tot 60 ton vis per jaar. Die beskikbare spesies sluit in tilapia, baber, harder, swartbaars en paling. Elke plaas sal bestaan uit agt uitgroeidamme van 'n halwe hektaar elk, 'n totaal van vier hektaar wateroppervlakte, 'n woonhuis en ses hektaar vir gewasse en veë. Die plase is ontwerp ten eide die voedingsryke uitvloeisel van die visdamme te gebruik vir besproeiing van die laerliggende landerye. Deur gebruik te maak van die beginsel van integrasie van 'n vis-, gewas- en vee-boerdery, aan die hand van die Chinese ontwikkelingsmodel oor die afgelope 2,000 jaar, word gepoog om niks te vermors nie. Die afvalproduk van een stelsel word 'n inset in die volgende. Hierdie benadering is uiters koste-effektief en leen homself tot organiese boerdery praktyke wat voldoen aan bewaringsbewuste en volhoubare boerderymetodes. Tweehonderd plaaseenhede sal 'n gesamentlike bydrae van 8,000 tot 12,000 ton per jaar lewer, wat gelykstaande is aan dubbeld die huidige gekombineerde varswater akwakultuurproduksie van al die SADC-Iedelande.

The white margined sole Synaptura marginata (Soleidae) was isolated as the most likely candidate for flatfish aquaculture in South Africa. The aim of the study was to screen the sole as a candidate aquaculture species by way of a comprehensive study of its biology and life history strategy and to identify possible "bottlenecks". The study was undertaken on the assumption that the biological data would provide valuable information for developing specific technologies that might be required for the farming of this species. Specimens were collected monthly by spearing along the Eastern Cape coast of South Africa between December 2000 and March 2002. Length-at-age data required for modeling the growth of S. marginata was obtained from sectioned otoliths. A Von Bertalanffy growth model with an absolute error structure best describes the growth for this species. The model parameters were: L∞ = 429.5 mm TL, K = 0.24 and t₀ = -1 .79 years. Analysis of gut contents showed that S. marginata feed exclusively on polychaete worms, mainly of the genus Morphysa. S. marginata shows a protracted summer spawning season of six months, from October to April. This was determined by the calculation of a monthly gonadosomatic index and a macroscopic maturity scale. Histological examination of the ovaries revealed five ovarian developmental stages. Size at 50% and 100% sexual maturity for females was calculated to be 235 mm TL and 300 mm TL (ca. 1.5 - 2.5 years of age) and all males> 154 mm TL were mature. S. marginata is a batch spawner, releasing a minimum of 3 batches of eggs per year. Relative fecundity is high (34000 eggs per year I kg) and this coupled with the protracted spawning season would make it possible to obtain adequate numbers of juveniles (for farming) for approximately five to six months of the year. Comparative analysis of the biological characteristics in relation to other soles farmed elsewhere in the world suggests that S. marginata is a suitable candidate for marine fish culture in South Africa.

The aim of this study was to evaluate the aquaculture potential of a hybrid between the two largest African silurid catfish, Heterobranchus longifilis (HL) and Clarias gariepinus (CG) . A morphometric, meristic and karyological study showed that the hybrid shared some of the physical characteristics of both C. gariepinus and H. longifilis, while its chromosome complement and fundamental number (2N = 54, FN = 95), was intermediate between that of H. longifilis (2N = 52, FN = 92) and C. gariepinus (2N = 56, FN = 97). The HLxCG cross could therefore be regarded as a true hybrid. For the characters tested, no morphological or karyological differences were apparent between the HLxCG hybrids produced in West Africa and those produced in southern Africa. In southern Africa, the HL♂xCG♀ cross had higher fertilization and hatching rates than pure strain H. longifilis, C. gariepinus or the reverse cross. There was no difference in the survival of the HL♂xCG♀ hybrid larvae and C. gariepinus larvae up to the onset of exogenous feeding. Pure strain H. longifilis juveniles had a faster growth rate than the H. longifilis ♂ x C. gariepinus ♀ juveniles, but the hybrid always grew at a faster rate than C. gariepinus or the reverse cross. The HL♂xCG♀ cross was consequently chosen as the hybrid with the greatest potential for siluroid aquaculture in southern Africa. The HL♂xCG♀ hybrid showed evidence of partial gonadic, gametic and post-zygotic sterility in both sexes. The hybrid was not completely sterile, as it was artificially induced to spawn, and a small number of viable F₂ hybrid and F₁ hybrid x C. gariepinus larvae were produced. However, in the light of its probable reproductive strategy, it is highly unlikely that the hybrid would pose an ecological risk to the southern African region. The H. longifilis ♂ x C. gariepinus ♀ hybrid was compared to C. gariepinus for selected water quality preferences and tolerances. The hybrid had a wider temperature preference (28 °C to 34 °C) than C. gariepinus (28 °C to 30 °C), but appeared to be more dependent on aerial respiration than C. gariepinus. The air-breathing frequency of hybrid fish began to increase at dissolved oxygen concentrations below 3 .8 mg.ℓ⁻¹, while C. gariepinus only showed an increase in air-breathing frequency at concentrations below 3.0 mg.ℓ¹. The hybrid was more tolerant of un-ionised ammonia (96-hour LC₅₀ = 9.1 mg.ℓ⁻¹) than C. gariepinus (96-hour LC₅₀ = 6.5 mg.ℓ⁻¹), but their 96-hour LC₅₀ salinity tolerances were similar (10.8-11.0 g.ℓ⁻¹). The H. longifilis ♂ x C. gariepinus ♀ hybrid had a higher fillet yield (43.9 %) than C. gariepinus (38.9 %), but the crude protein content and amino acid profile of the two groups were similar. Catfish are traditionally grown in earthen ponds under semi-intensive conditions in southern Africa, at around 4 kg of fish per cubic meter of water (kg.m⁻³). However, the hybrid could tolerate densities of up to 415 kg of fish per cubic metre of water, if the water was exchanged hourly (kg.m⁻³.hr⁻¹), and the density at which yield was optimised was rounded off to 400 kg.m³.hr⁻¹. The high threshold density and water quality tolerances of the H. longifilis ♂ x C. gariepinus ♀ hybrid indicates that it is ideally suited for highly intensive aquaculture. It was concluded that it would be more productive to farm the HL♂xCG♀ hybrid on an intensive basis in southern Africa, than it would be to farm C. gariepinus in the traditional manner.

There has been a long history of attempts to promote subsistence rural aquaculture within South Africa. Many of these attempts have failed due to inadequate support from government and support agencies. There has been a recent revived interest in promoting rural aquaculture development. Presented in this project are six scenarios demonstrating the potential application of thermal modelling techniques to improving subsistence rural aquaculture. These scenarios were based on a model validated against a real life system, and run with environmental data for the year 2005. Bovine manure, grass thatch, cereal straw and Typha spp. water reeds were tested for thermal performance. These results were then applied to the scenarios. The open and kraal enclosed pond scenarios yielded the widest deviation in temperatures throughout the year, with an average temperature of 3.8oC and 6.0oC above ambient and a temperature range of 10.6oC and 12.4oC for the year respectively. Eliminating solar radiation and reducing wind speed resulted in an average difference of 1.5oC below ambient and a temperature range of 7.5oC for the year. When completely enclosed in a well-sealed traditional Xhosa style hut, the pond had an average difference of 5.6oC below outside ambient temperature, with a range of 7.8oC for the year. A passive solar heating scenario added to the sealed hut scenario, which when run continuously maintained an average difference of 34.7oC above outside ambient temperatures, with a range of 56oC for the year. When a hypothetical 25oC temperature control was included in the model, the system maintained an average of 7.1oC above ambient outside temperatures, with a temperature range of 0.8oC throughout the year. The wider range of temperatures made available through the use of thermal modelling approaches provides a more diverse range of species available for subsistence rural aquaculture at any site, significantly improving its potential.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: In the aquaculture setting, opportunistic pathogens are present as part of the normal aquatic microflora, colonizing surfaces in fish tanks as part of biofilm communities, and often causing severe economic losses to the aquacultural industry. Isolates belonging to the genera Chryseobacterium, Elizabethkingia, Myroides and Empedobacter have been isolated from diseased fish, and are responsible for causing secondary fish infections, fish- and food-product spoilage, and have been described as etiological agents of various human diseases. Thirty-four Chryseobacterium and Elizabethkingia spp. and five Myroides and Empedobacter spp. isolates, obtained from various diseased fish species and biofilm growth in South African aquaculture systems, were characterised genetically using 16S rRNA gene PCR restriction fragment length polymorphism (RFLP), randomly amplified polymorphic DNA (RAPD) PCR, whole cell protein (WCP) and outer membrane protein (OMP) analyses. Genetic heterogeneity was displayed by the Myroides and Empedobacter spp. study isolates following OMP analysis, although 16S rRNA gene RFLP, RAPD-PCR and WCP analysis did not allow for differentiation of these isolates. A high degree of genetic heterogeneity was displayed by the Chryseobacterium and Elizabethkingia spp. study isolates following OMP analysis, 16S rRNA gene RFLP with MspI, and RAPD-PCR with primer P2. However, based on the results obtained by WCP analysis, 16S rRNA gene RFLP with CfoI and TaqI, and RAPD-PCR with primer P1 the isolates appeared genetically very homogeneous. High MAR indices and potential multi-drug resistance phenotypes were obtained for the Myroides and Empedobacter spp. and some of the Chryseobacterium and Elizabethkingia spp. isolates by antimicrobial susceptibility testing. Primary adherence and the influence of environmental changes on adherence was investigated by a modified microtitre-plate adherence assay. Nutrient composition, temperature and hydrodynamic incubation conditions were observed to influence adherence abilities of all study isolates. In addition, adherence varied greatly among isolates of the genera Chryseobacterium and Elizabethkingia, as opposed to a consistent strong adherence profile observed for the Myroides and Empedobacter spp. isolates. The influence of cell surface properties such as capsule presence and cell surface hydrophobicity, on primary adherence of the isolates was also investigated. Quantitative analysis of capsular material revealed the presence of thick capsular material surrounding the Myroides and Empedobacter spp. and some of the Chryseobacterium and Elizabethkingia spp. isolates, but could not be directly associated with adherence. Hydrophobicity were investigated using the salt aggregation assay (SAT) and bacterial adherence to hydrocarbon test (BATH). A very hydrophilic cell surface was observed for all of the Myroides and Empedobacter spp. isolates, and majority (74%) of the Chryseobacterium and Elizabethkingia spp. isolates. Cell surface hydrophobicity could not be correlated to the adherence of the Myroides and Empedobacter spp. isolates, and only SAT-determined hydrophobicity could be positively correlated to adherence of Chryseobacterium and Elizabethkingia spp. isolates under certain conditions. Coaggregation studies were performed between the study isolates and various important clinical and aquacultural microorganisms. High coaggregation indices were observed between the Myroides and Empedobacter spp. isolates and E. faecalis and S. aureus, and between E. faecalis, S. enterica serovar Arizonae, S. aureus and Listeria spp. and the Chryseobacterium and Elizabethkingia spp. isolates. Biofilm-forming capacity of the study isolates in an environment simulating their natural environment was investigated microscopically using a flow cell system. Typical ‘cone-like’ biofilm structures were observed for selected strains of both Myroides and Empedobacter spp. and Chryseobacterium and Elizabethkingia spp. isolates. The effect of increased hydrodynamics on biofilm architecture was seen through the narrowing of the biofilm structures and the formation of single cell chains towards the increased hydrodynamic area of the flow chambers. Chryseobacterium and Elizabethkingia spp. and Myroides and Empedobacter spp. appear to be potential primary biofilm-formers associating with a variety of microbes thus perpetuating their survival in a variety of aquatic habitats. / AFRIKAANSE OPSOMMING: Opportunistiese patogene kom gereeld in akwakultuur sisteme voor as deel van die akwatiese mikroflora wat dikwels biofilms vorm op oppervlaktes in hierdie sisteme. Visinfeksies veroorsaak deur hierdie patogene lei tot ernstige ekonomiese verliese vir akwakultuur industrieë. Chryseobacterium, Elizabethkingia, Myroides en Empedobacter spp. is reeds voorheen van verskeie geïnfekteerde visspesies geïsoleer hierdie bakterieë is verantwoordelik vir sekondere visinfeksies, die bederf van vis- en kosprodukte, asook menslike siektes. Vier-en-dertig Chryseobacterium en Elizabethkingia spp. en 5 Myroides en Empedobacter spp. isolate, geïsoleer vanaf verskeie geïnfekteerde visspesies en biofilm-groei in Suid Afrikaanse akwakultuur-sisteme, is geneties met behulp van 16S rRNS geen PKR restriksie fragment lengte polimorfisme (RFLP), toevallig geamplifiseerde polimorfiese DNS (TGPD) PKR, heel-sel protein (HSP) en buitemembraan protein (BMP) analise gekarakteriseer. BMP analise het getoon dat die Myroides en Empedobacter spp. isolate geneties heterogeen is, alhoewel 16S rRNS TGPD-PKR, TGPD-PKR en HSP analise nie tussen die isolate kon onderskei nie. BMP analise, 16S rRNS TGPD-PKR met MspI en TGPD-PKR met inleier P2 was meer suksesvol as HSP analise, 16S rRNS TGPD-PKR met CfoI en MspI, en TGPD-PKR met inleier P1, om onderskeid te tref tussen die Chryseobacterium en Elizabethkingia spp. isolate en het gedui op ‘n hoë vlak van genetiese heterogeniteit tussen hierdie isolate. Beide die Chryseobacterium en Elizabethkingia spp. en Myroides en Empedobacter spp. isolate het ‘n hoë vlak van antibiotika weerstand getoon wat dui op ‘n menigvuldigde antibiotika weerstands-fenotiepe. Primêre vashegting vermoëns en die invloed van omgewingsfaktore op vashegting is met behulp van ‘n gemodifiseerde mikrotiterplaat vashegtings toets ondersoek. Vashegting van die isolate is beïnvloed deur variasies in die samestelling van die medium, temperatuurveranderings en verskillende hidrodinamiese inkubasie kondisies. Inteenstelling met die sterk vashegtingsvermoë van die Myroides en Empedobacter spp. isolate, het die vermoë om vas te heg grootliks tussen die Chryseobacterium en Elizabethkingia spp. isolate gevarieer. Verder is ondersoek ingestel op die invloed van seloppervlak eienskappe soos die teenwoordigheid van kapsules en hidrofobisiteit op die isolate se vermoë om aan oppervlaktes te heg. Die Myroides en Empedobacter spp. isolate en verskeie Chryseobacterium en Elizabethkingia spp. isolate is omring deur dik kapsules, maar geen verband tussen vashegting en die teenwoordigheid van kapsules kon bepaal word nie. Die sout aggregasie toets (SAT) en bakteriële vashegting aan koolwaterstowwe (BVAK) toets was gebruik om die hidrofobisiteit van die isolate se seloppervlaktes te bepaal. Die Myroides en Empedobacter spp. isolate en 74% van die Chryseobacterium en Elizabethkingia spp. isolate het ‘n baie hidrofiliese seloppervlak getoon. Slegs die hidrofobisiteit bepaal deur die SAT toets het ‘n positiewe verwantskap met die aanhegtingsvermoë van die Chryseobacterium en Elizabethkingia spp. isolate getoon. Mede-aggregasie tussen die isolate en verskeie belangrike mediese en akwakultuur mikroörganismes is ook ondersoek. Die Myroides en Empedobacter spp. isolate het ‘n sterk assosiasie met E. faecalis en S. aureus getoon Die Chryseobacterium en Elizabethkingia spp. isolate het sterk met E. faecalis, S. aureus, S. enterica serovar Arizonae en Listeria spp. geassosieer. Vloei-sel studies is uitgevoer om die biofilm-vormingsvermoë van die isolate te ondersoek. Vir beide die Myroides en Empedobacter spp. en Chryseobacterium en Elizabethkingia spp. isolate is tipiese kegelagtige biofilm stukture waargeneem. Die invloed van verhoogde hidrodinamiese kondisies in die vloei-sel het vernouing van die biofilm strukture en die vorming van enkel-sel kettings tot gevolg gehad. Vanuit hierdie studie is afgelei dat die Myroides en Empedobacter spp. en Chryseobacterium en Elizabethkingia spp. isolate onder verskeie kondisies aan oppervlaktes kan vasheg en dus potensiële primêre biofilm-vormings organismses is. Hierdie organismes besit ook die vermoë om met ‘n verskeidenheid ander organismes te assosieer, wat waarskynlik hulle suksesvolle oorlewing in akwakultuursisteme verseker.

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The purpose of this study is to investigate the techno-economic feasibility of operating an aquaponics farm in South Africa. Aquaculture is the fastest-growing type of food production in the world, yet South Africa is lagging behind international efforts to boost the industry. An independent academic feasibility study on small scale aquaponics farms in South Africa has not been performed before, causing current and prospective farmers to be uncertain about the prospects of the venture. The study is approached by investigating the aquaculture and aquaponics industry and gathering the relevant information. By investigating other models used to represent aquaculture or aquaponics systems, the required information is gathered in order to build a unique model for the purpose of determining the feasibility of the case study farms. The model is modified to represent each of the case study farms. The results show that the majority of the farms are not economically viable. A sensitivity analysis provides some insight on how varying certain parameters can affect the performance of the systems. Using the information gathered in the case studies and research, a near-ideal system is specified in order to establish whether this improved system can be viable whilst taking into account the constraints placed upon aquaponics ventures in South Africa. The study suggests some recommendations for current and prospective farmers that might improve their chances of succeeding with an aquaponics venture. The study finds that currently aquaponics in South Africa is hindered by a number of constraints that result in it being a high-risk venture with meagre returns on investment. However, the study shows that if an aquaponics system were designed, built and managed correctly, it could theoretically be an economically viable venture. The investigation has, in a logical method, provided insight into the viability of operating an aquaponics farm in South Africa. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die lewensvatbaarheid van akwaponika in Suid-Afrika te ondersoek. Akwakultuur is die tipe voedselproduksie wat die vinnigste groei in die wêreld, maar Suid-Afrika hou nie tred met die internasionale poging om akwakultuur te ontwikkel nie. „n Onafhanklike lewensvatbaarheid studie oor kleinskaal akwaponika plase in Suid-Afrika is nog nooit onderneem nie. Dit veroorsaak dat huidige en voornemende akwaponika boere onseker is oor die uitkomste van hulle ondernemings. Die studie is benader deur die akwaponika en akwakultuur bedrywe te ondersoek, en die relevante inligting te versamel. Deur ander modelle wat gebruik word om akwakultuur en akwaponika sisteme te verteenwoordig te ondersoek, is die nodige inligting versamel om „n unieke model te bou wat gebruik word om die lewensvatbaarheid van die gevallestudies te bepaal. Die model is aangepas om elkeen van die gevallestudies te verteenwoordig. Die resultate wys dat die meerderheid van die gevallestudie plase nie ekonomies lewensvatbaar is nie. „n Sensitiwiteitsanaliese gee insig oor hoe spesifieke parameters die prestasie van die sisteme affekteer. Deur die inligting wat versamel is tydens die gevallestudies en navorsing te gebruik, kan „n sisteem gespesifiseer word om te bevestig of hierdie verbeterde sisteem lewensvatbaar kan wees terwyl dit die beperkings waaronder akwaponika sisteme in Suid Afrika geplaas word in ag neem. Die studie verskaf „n paar aanbevelings vir huidige en voornemende boere. Hierdie aanbevelings kan die kanse van sukses van die ondernemings verbeter. Die studie het gevind dat akwaponika in Suid-Afrika deur „n aantal beperkings benadeel word, wat lei tot „n situasie waar dit „n hoë-risiko onderneming is, met lae opbrengste op die belegging. Maar, die studie wys ook dat as „n sisteem korrek ontwerp, bou en bestuur word, dit teoreties „n ekonomies lewensvatbare onderneming kan wees. Die studie het op „n logiese wyse insig gegee oor die haalbaarheid van akwaponika in Suid-Afrika.

Thesis (MBA)--Stellenbosch University, 2005. / Some digitised pages may appear illegible due to the condition of the original hard copy / ENGLISH ABSTRACT: This study investigates the current level of aquaculture production in South Africa and factors which will help with its further expansion. Aquaculture provides jobs, can assist in alleviating poverty, can earn substantial amounts of foreign exchange and can give rise to various multiplier and linkage effects within the economy. As fishery products are processed further, it is significant that benefits have the potential of becoming more pronounced. Although the South African aquaculture industry has played a negligible role in the development of the domestic economy, its contribution has increased in recent years. Despite providing few employment opportunities, the local aquaculture industry is export-orientated and has the potential of becoming an important foreign-exchange earner. In addition to being able to assist the country's balance of payments, a larger domestic industry could, through its various linkages with the rest of the economy, provide the impetus for the establishment of various related industries. It is not only through these effects that the aquaculture industry could help create new employment opportunities, but the industry itself becomes more labour intensive the further it moves down the processing chain. The prospect of these potential benefits has moved the state to establish various aids to assist the development of the local industry. The most important of these are the Strategy for Biotechnology Development in South Africa, the White Paper on the Promotion of Small Business and a joint mariculture forum between industry and the state. There are factors in favour and factors against the aquaculture expansion. The benefits are too important to be discarded. And the disadvantages can be eliminated by various techniques that have already proved themselves elsewhere in the world. / AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die huidige vlak van akwakultuur in Suid-Afrika en die faktore wat die uitbreiding daarvan sal beinvloed. Akwakultuur skep werksgeleenthede, help met die verligting van armoede, dit kan aansienlike hoeveelheid buitelandse valuta vir Suid-Afrika verdien en gee aanleiding tot verskeie vermenigvuldiger effekte na die res van die ekonomie. Hierdie effekte is geneig om van groter omvang te wees indien visprodukte verder verwerk word. Alhoewel akwakultuur tot op hede 'n weglaatbaar klein bydrae gemaak het tot die ontwikkeling van die Suid Afrikaanse ekonomie, het hierdie invloed in die afgelope jare toegeneem. Die akwakultuur industrie onderhou relatief min werksgeleenthede, maar is uitvoer ge-orienteerd en het die potensiaal om in belangrike verdiener te raak van buitelandse valuta. Behalwe vir die voordelige uitwerking wat die bedryf het op die betalingsbalans, kan 'n groter akwakultuur bedryf, deur verskeie vermenigvuldiger effekte, aanleiding gee tot die oprigting van verbandhoudende bedrywe. Behalwe vir die werksgeleenthede wat hierdeur ontstaan, word die visbedryf algaande meer arbeidsintensief en voorsien dit meer werksgeleenthede soos daar langs die waarde toevoegingslyn afbeweeg word. Die verwagte voordele wat die industrie kan bied, het die staat oortuig om sekere hulpmiddels tot stand te bring om die uitbreiding te bevorder. Die belangrikste hiervan is die totstandkoming van 'n Strategie vir Biotegnologiese uitbreiding, 'n beleidsdokument vir die bevordering van klein besighede en 'n akwakultuur samewerkingsplatvorm tussen die staat en die bedryf. Daar is faktore wat die plaaslike uitbreiding ondersteun en ander wat 'n nadelige invloed mag veroorsaak. Die positiewe faktore is te belangrik om die geleentheid nie te benut nie. Die nadelige faktore kan voorkom word deur tegnieke te gebruik wat hulself reeds suksesvol bewys het.

Thesis (MTech (Oceanography))--Cape Peninsula University of Technology, 2010 / Coral reefs are in a worldwide state of crisis due to overexploitation. One of the factors contributing to the over exploitation is the marine ornamental industry. This industry utilises a diversity of organisms, comprising approximately 1470 species of fish and more than 300 species of invertebrates. Between April and December 2007, five of the 18 companies who had import permits for South Africa, imported a total of 359 different ornamental species, 252 of these were fish species while the remaining 107 species were invertebrates. During these nine months a total of 32 005 individual organisms were imported into South Africa by the five companies. There were two groups of fish that represented the highest import volumes. These were Amphiprion spp. and Pomacentradae spp., as well as the Gobidae spp. These groups represented 38% and 19% respectively of the total number of fish imported" Aquaculture has the potential to substantially reduce the harvesting pressure on coral reef organisms globally. A small-scale multi-species mariculture system was designed and constructed for benthic egg-laying species of fish (brood stock), corals, and ornamental algae. The system was designed to be low cost and easy to operate. The total capital costs for the system was R15 680.70. In order to estimate the potential yield of an aquaculture facility it is important to know the growth rate of the proposed species under pilot conditions. The use of artificial lighting regimes in aquaculture comes at a financial cost. It is for this reason that it is important to know what lighting scenario yields the highest growth rate of corals. The effects of photoperiod were tested on Sinularia sp. of coral. Two photoperiods were tested, namely: Groups (8:16 h Iight:dark cycle) and Group12 (12:12 h light:dark cycle). No significant difference in weight was found between Group8 and Group12 (p = 0.975). There was however a significant increase (p = 0.002) in Surface-area Pixel Value (SPV) for Groups (1996.73 millipixels pixel-1 day -1) compared to Group12 (983.73 millipixels pixel-1 day -1). The use of a 8:16 h lightdark cycle can thus yield coral of a larger size but not necessarily a higher mass.

Thesis (MPhil)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Emerging global trends towards sustainable development have placed emphasis on the need to create sustainable food value chains. Many food value chains are becoming weakened through their reliance on eco-systems that are deteriorating. Furthermore, while food systems are under threat, global food consumption is on the rise. The conundrum seems inescapable. Humanity’s food supply methods have moved on from hunter-gatherer characteristics apart from the exception of the fishing industry. The current generation may be the last to witness the wide-spread practice of fishing. Aquaculture, and in particular fish-farming, has begun to show much potential as a method of producing sustainable sources of protein. Whether this can be utilized in the South African context is a challenge that needs to be verified. This research, presented as two articles, explores the potential for the development of the fish-farming sector in South Africa, and recommends suitable species. Although there is some literature on how fish-farming may have a place in South Africa’s sustainability quest, it is scarce. This research aims to enhance the literature base on fish-farming in South Africa, as well as provide further evidence on what the true potential is for fish-farming in South Africa. This was done through a series of primary and secondary data collection methods that allow for a thorough analysis of fish-farming in South Africa and the species involved. The analysis revealed that the fish-farming sector and the cultivatable species in South Africa are met with an array of opportunities and challenges. Overcoming these challenges will open the doors to exploit the opportunities available. / AFRIKAANS OPSOMMING: Opkomende globale tendense weerspieël dat dit noodsaaklik is dat klem gelê moet word op volhoubare ontwikkeling en dat dit van uitterste belang is om volhoubare voedsel waardekettings te skep. Verskeie voedsel waardekettings raak verswak deur hul afhanklikheid van eko-stelsels wat vernietig word. Verder, terwyl voedsel stelsels bedreig word, is globale verbruik van voedsel besig om te verhoog. Dié raaisel lyk onvermydelik. Mensdom se huidige voedselvoorraad metodes het aansienlik ontwikkel van dié van die jagter-versamelaars, met die uitsondering van die visbedryf. Die huidige generasie mag die laaste wees, wat die wyd verspreide praktyk van visvang beoefen, om daarvan te getuig. Akwakultuur, in besonder vis-boerdery, het begin om potensiaal te wys as 'n volhoubare bron in die vervaardiging van proteïen. Of dit in die Suid-Afrikaanse konteks gebruik kan word, is 'n uitdaging wat geverifieer moet word. Hierdie navorsing, wat aangebied word as twee tydskrifartikels, ondersoek die potensiaal vir die ontwikkeling van vis-boerdery in Suid-Afrika, en beveel ook gepaste spesies aan. Alhoewel daar sommige artikels is oor hoe vis-boerdery kan in pas in Suid-Afrika se soeke na volhoubaarheid, is dit skaars te vinde. Die navorsing beoog om die literatuur basis van vis-boerdery in Suid-Afrika op te skerp, en ter selfde tyd verdere bewys te gee oor die ware potensiaal van vis-boerdery in Suid-Afrika. Dit was gedoen deur 'n reeks van primêre en sekondêre data-insameling metodes wat voorsiening maak vir 'n deeglike ontleding van visboerdery in Suid -Afrika en die spesies betrokke. Die ontleding het getoon dat die vis-boerdery bedryf en die aankweek spesies in Suid-Afrika verskeie geleenthede en uitdagings in die gesig staar. Oorwinning van hierdie uitdagings sal dit moontlik maak om die beskikbare geleenthede te ontgin.