Despite being a low fat fish and consequently a low omega-3 fish, tilapia have widespread consumer acceptability due to its mild taste, cheap price and low mercury content. However some sources claim that farmed tilapia can be detrimental to human health due to high omega-6:3 ratios and low omega-3 content specifically eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid. The objective of this study was to create an omega-3 enriching feed that would increase omega-3 content in tilapia and subsequently decrease the omega-6:3 ratio. An 8 week feeding trial was conducted. Tilapia were cultured in a recirculating aquaculture system on one of eight diets (control, commercial, 1, 3, 5% fish oil or 1.75, 5.26, 8.77% ALL-G-Rich (algae). Water quality, selected fish biometrics and growth performance were recorded. Fillet and rib meat tissues were collected at weeks 4 and 8, and liver and mesenteric fat tissues were collected at week 8. Fat was extracted, trans-methylated and identified as fatty acid methyl esters using gas chromatography-mass spectrometry. Docosahexaenoic acid increased in concentration in all tissues as percent fish oil and ALL-G-Rich increased in the diets with 8.77% ALL-G-Rich resulting in significantly (P<0.0001) greater concentrations in the fillet and mesenteric fat compared to all other diets after 8 weeks. The 8.77% ALL-G-Rich diet resulted in significantly (P=0.003) greater cumulative accumulation of EPA, DPA and DHA on a mg/4oz fillet basis after 4 weeks compared to control. The results of this study suggest that an ALL-G-Rich finishing feed could be produced that would result in a value added farmed tilapia fillet. / Master of Science in Life Sciences

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.

The objective of this dissertation was to evaluate the feasibility for integrating aquaculture with agriculture on irrigated farms. I developed a pulsed flow culture procedure for culturing fish in irrigation ditches where water was replaced once daily. Water from the fish culture operation was than used to irrigate ornamental trees (mesquite) for sale to the nursery industry. Twelve and four tenths percent of the channel catfish survived the 90 day experiment whereas 88.5% of the tilapia survived. These differences were statistically (P < 0.05) significant and may indicate that red tilapia are better suited than channel catfish for culture in pulsed flow culture systems. Densities of 10 and 20 tilapia/m³ showed the best performance among the five densities (10, 20, 30, 50, and 70 fish/m³) tested. Water quality limited the density of fish that could be cultured in this type of pulsed flow culture system. Ammonia concentrations and levels were periodically high (5 ppm) and dissolved oxygen levels were periodically low (1.5 ppm). Each 100 meters of ditch could potentially produce between 240 kg and 420 kg of tilapia per growing season. In all treatments, the length and weight of red tilapia predicted by Santos' equation closely followed the empirical data. There was a significant difference (p ≤ 0.001) in the growth (height and stem base area) of mesquite trees irrigated with well water and those irrigated with water that was from the fish culture facility. Trees of the size produced with water from the fish facility could be sold after about six months for prices ranging from $5.50 to $8.50. Trees irrigated with well water would take twice as long to reach a marketable size as those irrigated with water used for fish culture. The integration of aquaculture with agriculture using pulsed flow culture systems seems to have the potential to increase cash flow from irrigated farms. The production of fish and ornamental trees with the same water used to irrigate agronomic crops seems biologically, technically, and economically feasible.

One result of the search for inexpensive alternative sources of protein has been the rise in interest in aquaculture, the rearing of aquatic organisms under controlled conditions. In this dissertation we examine several management approaches to the efficient rearing of aquatic animals, using mathematical modeling to discover optimal production decisions. In addition we demonstrate the feasibility of simultaneous decision and performance control, providing empirical support for a theoretical extension of traditional variance analysis techniques. The results of three studies are included. In the first we model a situation in which the manager of an aquaculture system must decide when and how many animals to stock initially, how many animals to harvest each period, and when to restock an enclosure in order to maximize contribution. We consider both limited and unlimited growing seasons, solving mixed-integer and linear programs. We examine the effects of technological improvements on production strategies. Consistent improvement in contribution is noted, along with some variation in strategy. In the second study we introduce seasonal variation in revenues and lengthen the growing season. The resulting large-scale real-world mixed-integer problem necessitates the use of a heuristic and two strategies, selective expansion and sieve, in order to achieve a near-optimal solution within a reasonable length of time. In the third study we focus on the uncertainty inherent in the aquaculture environment. We provide empirical evidence of the feasibility of a performance evaluation system which gives explicit consideration to the effects of environmental uncertainty and incorporates intraperiod adaptive behavior on behalf of the individual responsible for implementation of model-specified activities. The system we describe may be used in the simultaneous evaluation of individual and model performances, thus clarifying responsibilities for variances and improving production control.

<p> Daily ring formation has been validated for a variety of fish species, but there is little known information or data on ageing young of year Alligator Gar (<i>Atractosteus spatula</i>). Artificially spawned Alligator Gar fry with a known spawn date, hatch date, and swim-up date were stocked into two ponds at Tishomingo National Fish Hatchery and reared from 9 to 91 days post-hatch. Up to 10 individuals were sampled each week, and age in days was estimated from counts of presumptive daily rings in the otoliths (sagittae, lapilli, and astericsi). Mean daily ring count and known age were closely related to swim-up (sagitta r² = 0.98, lapillus r² = 0.99, asteriscus r² = 0.93) indicating that daily ring deposition occurred in the otoliths of Alligator Gar 2 days after swim-up. Daily increment counts were accurate through 73 (sagitta), 86 (lapillus), however accuracy for asteriscus was very low throughout 86 days from swim-up. Age-bias plot for the lapillus visually showed no bias between readers. The resulting regression of ring counts against known age (age = -0.96 + 1.03*estimated age) was applied to wild caught Alligator Gar collected in the summer of 2013 from Lake Texoma, Oklahoma, to estimate spawn dates. Spawn dates seem to coincide with rising pool elevation of Lake Texoma and water pulses of tributaries.</p>

The growth of aquaculture industry, and in particular of salmonids, has dramatically increased in the last decades to supply the growing worldwide demand for fish products. The expansion of aquaculture needs a good management to ensure the sustainability of this activity. In particular, improving feeds for aquaculture to enhance health and performance of reared fish is imperative for this industry. Molecular biological approacches can help interpret responses to new diets and immune responses. Ubiquitin ligases (UbE3s) play a pivotal role in the ubiquitin proteasome pathway of protein degradation and are markers that could be linked to health and performance of fish. Six UbE3s were characterized, 4 are related to muscle catabolism and two involved in NF-kB activation. Atrogin-1 and MuRF genes were increased following food deprivation and a proinflammatory stimulation. MULAN and Mul1b, are mitochondrial activators of NF-kB and the expression of both genes was increased following a proinflammatory immune challenge both in vivo and in vitro. These genes have been used as markers in dietary traits to understand responses. A transcriptome study using Atlantic salmon fed a commercially available functional feed designed for optimal health status compared to a standard feed was performed. Both the liver and muscle were chosen for the transcriptomic analysis. In liver, a number of process were found down regulated, including protein turnover and innate immunity. No significant alterations were found in muscle. To determine the effect of a high plant protein diet (PP), compared to a marine profile diet (MP) in Atlantic a transcriptomic analysis was performed. Fish grew equally well on both diets and no significant histological differences were seen in intestine. The PP diet induced tissue specific changes in gene expression, with the mid intestine showing activation of the adaptive immune response and protein turnover. In liver cell proliferation and apoptosis indicate cellular reorganization and also a general suppression of processes such as immune response was observed. In contrast muscle tissue showed reduced protein metabolism and decrease in immune gene expression suggesting less energy expenditure in this tissue. To assess fish response to Piscirickttsia salmonis, the etiological agent of the salmonid rickettsial seeticemia (SRS), a transcriptomic analysis was carried out. P. salmonis infection has profound effects on transcription in the head kidney, liver and muscle of salmon. Head kidney, liver and muscle tissue showed a decrease in expression of mRNAs related to acquired immune function indicating the pathogen is down regulating this response controlled in part by the inhibition of the G-protein signalling pathway, whereas the innate immune response was increased in head kidney. Liver and muscle also responded, including specific responses in each tissue type. These results improve understanding of the mechanisms by which this bacterium survives and replicates within host cells and may assist selection of molecular biomarkers useful for the development of a diagnostic tools, vaccines and therapeutants for the aquaculture industry. Using markers selected from the previous experiments, the effect of four different diets, a marine profile diet (MP/FO), a plant protein diet (PP/FO), a vegetable oil diet (MP/VO) and PP/VO diet, in Atlantic salmon were examined. Markers for protein and lipid metabolism and immune response were studied in mid intestine, liver and muscle of fish fed for 77 days the four diets. Small but significant changes were observed, but despite of this, fish fed all the four diets showed similar growth rates. Moreover, to study the possible effect of the diets on fish health, the expression of specific SRS markers was studied in head kidney and liver of fish fed the four diets and infected with P. salmonis. The SRS challenge demonstrated that all groups of fish were able to respond efficiently to the pathogen. In conclusion, these new diets may represent good alternatives to fish meal (FM) and fish oil (FO) diets indicating that a replacement of marine diets with vegetable sources is possible in Atlantic salmon without affecting neither fish growth and performance nor the health of fish. The findings presented in this thesis suggest that E3 ligases are good molecular markers, allowing to study performance and health of fish following feeding trial and pathogen challenge. In addition, transcriptomic analysis performed to select further key molecular markers involved in a variety of processes and improved our knowledge of fish physiology and immunology, providing useful information for the development of new alternative diets for aquaculture.

This thesis is an investigation of the basic biology, reproductive behaviour, and key physiological and nutritional requirements of the Mexican and Central American cichlid Cichlasoma urophthalmus (Gunther), with particular reference to the potential of native species for aquaculture in the region. C. urophthalmus is a widely appreciated food fish within its native range, commanding good prices and having the advantage in terms of aquaculture that the risk from introduction of an exotic species with the consequent importation costs, diseases and escapes are eliminated. The dentition, gill rakers and gut structure are indicative of a carnivorous habit and this was corroborated by seasonal examination of gut contents which revealed that the species feeds principally on small animals. Investigation of the species in the natural environment suggest that growth was continuous, with some slight depression in the cooler winter months, reproduction occurred in the second year and the minimum reproductive size was 102cm (50g). In the laboratory C. urophthalmus grew well between 22.5 and 36.3°C the best growth being achieved at 32°C and optimum growth and survival (- production) being at 28°C. The species is typically euryhaline and can be acclimated to salinities of 0% to 35%. It can withstand instantaneous transfer from O to 15%, and reverse, and have best growth at 15%, probably due to the energy saving in an isotonic medium. Oxygen consumption rates were similar to other cichlids and C. urophthalmus can survive virtual anoxia for about 2h. C. urophthalmus is a bottom-spawner and the aggressive features of its reproductive behaviour, described in this work, can probably be minimized in culture. Its fecundity is about 5 to 7 times that of the mouth brooding tilapias, producing 2000-7000 eggs per spawn and it can reproduce at about 23 days intervals, probably throughout the year with management of temperature. Hatching is rapid (61 days) and survival good with simple hatchery techniques. Broodstock requirements, handling and labour costs could be lower than for the mouth brooding tilapias. The protein requirements of fry were shown to be 39-45% of the diet and this is similar to the tilapias. Diet digestibility was depressed by high dietary fibre content, but was not inhibited by inclusion of soybean (25.81%) or wheat meal (26.7%) in the diets. Although much more research is required. The results reported here have enabled tentative formulations of diets for aquaculture, based on typically available ingredients. The features of C. urophthalmus are discussed and compared extensively with those of the other cultured fish, principally the tilapias. It is concluded that C. urophthalmus is a very good candidate for aquaculture development within its range of distribution and that it has strong advantages over introduction of cultured cichlids.

The copper uptake and toxicity of young and market-size tilapia, Oreochromis niloticus, exposed to copper sulP'hate were investigated. A series of preliminary experiments were conducted to provide requisite information for the final experiment. Preliminary experiments established uptake by the culture systems, feed and/or faeces, and. the impact of fish nutritional state on uptake. Other experiments established the median lethal concentration of copper to this species, an extrapolated minimal lethal concentration, and the optimum exposure duration and concentration for copper uptake. The remaining preliminary experiments defined the relationship between toxicity and uptake in small compared to market-size tilapia, and between muscle location (within the fillet) and copper uptake. The final experiment established the amount of copper uptake in the edible tissue of market-size tilapia after a worst-case exposure to copper sulphate. The worst-case was defined as the maximum non-lethal concentration for a period significantly exceeding that encountered in commercial production systems. The worst-case experiment comprised market-size fish (350 to 570 g) being exposed at a nominal concentration of 365 ppb copper for nine days. This study demonstrated that copper did not accumulate in the edible tissue of tilapia above that measured in non-exposed control fish. A mean level of copper in the edible muscle of non-exposed fish, as measured by atomic absorption spectometry, was 2.14 pprn (dry page weight basis), while in fish exposed to a nominal concentration of 365 ppb of copper it was found to be 2.31 ppm. These data are suitable for incorporation into a United States Food and Drug Administration, New Animal Drug Approval application for the approval of copper sulphate use as a drug for aquatic species.

The digenean Stephanochasmus baccatus (Nicoll, 1907) is a parasite found in marine flatfish which are of importance to the mariculture industry in Scotland. In the area of study, Loch Ewe, on the North-west coast of Scotland, the first intermediate hosts are the gastropods Buccinum undatum (L. ) and Neptunea antiqua (L. ). Several species of teleost fish of the Order Heterosomata act as second intermediate host and the definitive host is Eutrigla gurnardus (L. ) or Myoxocephalus scorpius (L. ). Aspects of the host/parasite relationships at all the host levels were investigated. Samples of B. undatum and N. antiqua were collected from May to September and the incidence of the natural infections of the major digenean species were recorded. In some samples, height, weight and copulatory organ length were measured with a view to finding an indicator of parasitism. The histopathology of S. baccatus in the molluscan host was described and seasonal changes discussed in relation to observed variations in the infectivity of cercariae to second intermediate hosts. Groups of 1+ fish were experimentally infected with cercariae at intervals from May to September when no more S. baccatus infections were found in the molluscs. Differences in the infectivity of the cercariae during these months were demonstrated. The pattern of glycogen deposition in both the molluscan digestive gland-and the intra-molluscan larvae were studied in an attempt to explain the loss of infectivity in cercariae in July and August. A. reduction in infectivity of cercariae after ageing was demonstrated experimentally by infecting fish with cercariae which were freshly dissected out and with cercariae kept for 10 hours at 12°C. This loss of infectivity was correlated with loss of glycogen from cercarial tails. A variety of I-group intermediate host species were infected experimentally and the distribution of cysts in the body, fins, skin and muscle were compared with the turbot, Scophthalmus maximus (L. ) and the plaice, Pleuronectes lap tessa L. These were shown to differ significantly. Four species of intermediate host which are of culturable significance, S. maximus, P. platessa, the common. dab, Limanda limanda (L. ) and the Dover sole, Solea solea (L. ) were experimentally infected and the tissue responses to invasion and encystment of S. baccatus were examined sequentially. The inflammatory response and metacercarial growth in each species of fish were found to differ in some important aspects which affected the subsequent viability in the definitive host. The viability of metacercariae from P. platessa and S. maximus were tested by controlled infection of the definitive host M. scorpius. A number of wild caught definitive hosts were examined for natural infections. An attempt gras made to describe the seasonal cycle of events in the life history of S. baccatus based on the information from this and other studies. The relative significance of different host species in different geographic locations was discussed.

Sanguinicola inermis Plehn, 1905, a recently introduced fish pathogen in Britain, has caused considerable damage to the carp industry. Two severely affected fish farms in England were included in the study. The incidence of fish infection for both farms was high, being 74-84% in 0+ and 1+ carp. Studies were made on the infection process and details of route of entry, migration and maturation of the worm are presented. An apharyngeate, furcocercous, lophocercous cercaria which develops in the snail Lymnaea (Radix) peregra (Mü11) was shown experimentally to develop into an adult Sanguinicola inermis. Maximum penetration of cercaria was achieved within 30 minutes and fins appeared to be the preferred site. Large numbers of worms were found to remain in the skin after penetration where they continued to develop to maturity, a previously unreported feature of S. inermis infection. The greatest migration to preferred loci occurred at 60 days post infection immediately prior to egg production. The migratory route used was found to be the loose connective tissue as well as the circulatory system. The distribution of mature worms in major blood vessels changed with season. Light microscopical studies were made on the morphology of specimens collected from the two farms and these were identified as S. inermis. Scanning electron microscopy of the surface topography and transmission electron microscopy revealed details of the tegument and provided evidence for the absence of spines. The major developmental features of the worm are described. A marked increase in size occurred up to 36 hours post penetration. Subsequent growth was slower. Egg production by mature worms began 10 weeks post infection at 15°C. Distribution and development of eggs in tissues is described. Egg production continued throughout the year with peaks during the summer months despite the constant environmental conditions. The growth rate of 0+ fry was studied over a period of 16 weeks and heavily infected fish showed stunted growth and poor Specific Growth Rates, Protein Efficiency Ratios and Food Conversion Ratios. Haematological studies showed that infected fish suffered from hypochromic macrocytic anaemia with leucocytosis and an increased Erkhrocyte Sedimentation Rate. Three different phases of infection were recognized. During phase I, the invasive stage, mortality may occur if infection levels are extremely high, but lightly infected fish present as clinically normal. Phase II was found to be the most critical phase since the majority of fish (over 90%) died at this stage. Histopathology revealed the progress of the infection from cercarial invasion to worm migration, maturation, egg production and miracidial hatching. Pathological changes were observed in the skin in phase I. In phase II, the heart, gills and kidneys were severely affected by both mature worms and developmental stages. The infection reached a chronic stage during phase III evidenced by a granulomatous tissue reaction largely in response to residual eggs in tissues. An attempt was made to integrate the phases of infection, development of the worm and pathogenesis in order to elucidate the host-parasite relationships.