A major obstacle facing the successful creation of an African aquaculture industry, based upon Oreochromids, is the irregular supply of good quality fish seed. There are several causative biological processes behind its irregular supply. The aim of this research was therefore to determine the basic requirements for the establishment and maintenance of a small breeding facility, for O. mossambicus. The goal was to make a unit that was simple and which could be easily replicated in rural, satellite aquaculture seed stations. The results obtained illustrate that a small reproduction unit can produce large quantities of healthy 90-day fry. Asynchronous hatching of the eggs and spawning asynchrony in female Oreochromis mossambicus are two elements which negatively affect uniformity in the fry produced. Typical fish seed production uses large ponds partitioned into breeding allotments or a series of breeding pools. While the earthen ponds provide a substrate in which a nest can be excavated, its presence is not required for mating success in the closely related O. niloticus (Linneaus 1758). Female mate choice, as well as apparent fecundity, according to nest size has been clearly recorded in related cichlids but no investigations have been made as to nest size and spawning synchrony in O. mossambicus. The main focus of this investigation was to ascertain whether O. mossambicus would accept artificial nest substitutes in preference to their own constructed ones and secondly, whether different alternatives would elicit different levels of acceptance. The observed results indicate a ready acceptance for artificial nest alternatives, with nest lip height being prioritised by the fish . The implications thereof are discussed in relation to the potential for optimization of breeding arenas for O. mossambicus by the provision of artificial nests whose dimensions satisfy both male and female preferences. In established communities, Oreochromis mossambicus display various complex and ritualised behaviours during stable and disruptive events. The aim of this research was primarily to produce a glossary of behaviours defining these interactions, particularly with reference to male-male behaviours. Three males and six females were allowed to acclimatise over one month, with various social groupings being established within the first few days. Results from this study illustrated not only a dynamic social structure, signaled via various chemosensory and visual methods, but also supported recent findings in apparent male-male courtship and the underlying ii causes. Furthermore, the observed male-male activity of the nestholder malesfirmly corroborate the current practice in aquaculture whereby only one male is allocated per breeding arena. The use of artificial incubation of Oreochromis spp. eggs has become widespread in high intensity fish seed production. Various types of incubator exist, and their selection is dependent on the specific attributes of the egg to be incubated. Currently available incubators are typically of a funnel (up-flow) or round bottomed (down-flow) design. Neither permits easy access to the eggs, which is particularly important when dealing with poor quality water as is typically found in rural areas. The aim of this study was to devise and test an easy-to-use incubator, applicable to rural seed production projects, which offers advantages over currently available incubator types. The final design, WETNURSE Type II, offered improved hatching rates over Type I, with a mean hatching success of 75%. While falling short of the desired 80% success rate (Rana 1986), the various other benefits provided by the design justify further optimization and testing. Three distinct populations of O. mossambicus, representing populations of inbred, randomly mated and genetically unknown (wild-caught) pedigree were analysed according to their food conversion efficiency (FCE). The intra- and inter-sample crosses were done with single males in order to produce half-sib progeny batches which allowed for the assessment of sire influences on the FCE of the progeny batches. The results show that the population of unknown pedigree is comparable to that of the randomly mating population, indicating the presence of sufficient genetic variation to permit further selection; the genetic contribution of the males to their respective progeny was insignificant in relation to that made by the female.

Sustainable development of export-orientated farmed seafood in Thailand is a major issue which can impact local stakeholders as well as global food security. The major species taken into consideration in this research were initially the Pacific white shrimp (Litopenaeus vannamei), Nile tilapia (Oreochromis niloticus), giant freshwater prawn (Macrobrachium rosenbergii), and striped catfish (Pangasianodon hypophthalmus). After which more focus was placed on Pacific white shrimp, which is Thailand’s major cultured seafood being traded for export, and tilapia, which has potential for export but also enjoying a good domestic market demand. Actors or stakeholders directly and indirectly involved in aquaculture value chains may have their own perceptions about sustainability affecting their operations, as various factors within and outside their own systems could affect these perceptions. This could lead to different efforts in responding to these factors to make their operations sustainable. Three major areas were covered in this study, namely a) describing the strengths and weaknesses of shrimp and tilapia production in Thailand in relation to their export potential, b) evaluating the status of compliance to global aquaculture standards of shrimp and tilapia farming (covering technical and labour aspects), and c) determining perceptions of sustainability across the shrimp and tilapia value chains in Thailand, with a focus on the production sector. A mixed-methods approach was employed to obtain information in the study sites in Thailand. Basic field interviews were conducted among 206 shrimp producers in 6 provinces in the east and south, and 199 tilapia producers in 4 provinces in the west and east, in terms of farm operations and perceptions of factors which will affect the sustainability of their operations, including generational aspects on future shrimp and tilapia farming. Key informant interviews were also conducted among other value chain actors (>30) such as hatchery/nursery operators, input/service providers, processors/exporters and technical/ institutional members to determine whether there are differences in their sustainability perceptions. In addition, face to face interviews with 18 shrimp farm male and female workers were conducted (Thai and migrant workers), as well as with 14 key informants involved in shrimp farm labour issues in Thailand, specifically for well-being and working conditions. Stakeholders cited environmental (technical), economic, social and institutional (equity) aspects of their operations as factors which will affect the sustainability of their operations. Disease, product price and water quality were the three most important sustainability factors among shrimp farmers, whereas water quality, disease and extreme weather conditions were for tilapia farmers. Product price was the most cited by input service providers, hatchery operators, shrimp and tilapia producers, and processors. Both Thai and migrant shrimp farm workers perceived a better or much better-off quality of life working in shrimp farms in Thailand than in their previous occupations or status. Almost all shrimp farms meet more than what are required under the Thai labour law or the global aquaculture standards for human resources. With the importance of migrant labour in Thailand, much still needs to be done in terms of assessing the impact of their working in Thailand on their families left behind in their own countries, as well as on their communities, including status of social protection to avoid exploitation. Each stakeholder group strives to achieve sustainability so they can remain in operation in the next few years, to survive on the business individually and corporately, and to be the best provider of sustainably and ethically produced seafood for the world. The compliance to aquaculture global standards and certifications may be considered to contribute to the sustainability of operations by improving farm practices thereby reducing detrimental impacts on farm and external environments, as well as strengthening human relations with in the farm and in the community. However there are some aspects of these standards which could eliminate the small players. In this study, the large scale farms were more likely to comply with all the standards, followed by medium scale, and lastly the small scale farms. The differences in perceptions which exist among these stakeholders should be understood by every sector and efforts should be made to address them so that there is cohesiveness in giving support to achieve sustainable seafood production and trade.

Over the last 3 decades, freshwater aquaculture has become one of the most important food industries. However the constant introduction of a reduced number of very successful species for aquaculture has been identified as one of the main activities related to the alarming decline of fish biodiversity worldwide. This issue has raised awareness amongst the scientific community, governmental authorities and the general public towards freshwater fish biodiversity. This new awareness has promoted the development of “green” markets and environmentally friendly strategies, aiming for a reliable production of protein sources. The development of native species aquaculture has been presented as a strong alternative for sustainable aquaculture and the protection of biodiversity. However, it seems clear that unplanned native species aquaculture developments can be as detrimental on local biodiversity as the introduction of exotic fish, if not more dangerous. Therefore, the advantages and disadvantages of native species aquaculture have to be clearly analysed before any aquaculture development. This study aimed to establish a philosophical background regarding the use of native fish species in aquaculture in contrast to the introduction of exotic species that may compete for a similar niche as food in local markets. The main ecological impacts that exotic fish species may have on natives, such as competition, predation, and hybridization were discussed. In addition, a well planned native species Aquaculture Strategy for the Protection of Biodiversity was produced, at catchment level, within a Geographic Information System (GIS). For the development of the native species aquaculture strategy in central Mexico, four species of Atherinids (Chirostoma estor, C. Jordani, C. promelas and Atherinella balsana) and two species of native Ictalurids (Ictalurus balsanus and Ictalurus dugesii) were included in this study. These six species are relatively new to aquaculture and they were selected on the basis of their importance in local fisheries and markets in their native basins of the Lerma-Santiago and Balsas rivers. Both of these basins are of great importance in central Mexico, not only because of their biodiversity but also because of their high human population densities and socio-economic status. The use of Geographic Information Systems was a fundamental factor in the development of the native species aquaculture strategy at catchment level, consisting of site suitability models (SSM) for each species in their corresponding native catchments. Overall, SSM identified 13,916 km2 and 11,178 km2 highly suitable for aquaculture of the studied Atherinids and Ictalurids respectively, based on Water, Soil and Terrain, Infrastructure and Risk sub-models. A set of predictive species distribution models (PSDM), which related ecological characteristics for each studied species with relevant environmental and topographic parameters into a GIS, were also produced. Such models were developed for the establishment of potential natural ranges of distribution for each species, as well as their potential to become exotic in new environments, as a potential for invasion model (PI). Based on a partial verification, both PSDM and PI models produced results that were satisfactorily consistent with the known distribution of each modelled species. The combination of SSM and PSDM produced an Aquaculture Strategy for the Protection of Biodiversity model (ASPB) which identified the most environmentally friendly suitable areas for aquaculture sites. In contrast, the combination of the SSM with PI models into an ASPB model identified the site suitability potential for non-native species that are genetically close to native ones, in an attempt to reduce the known impacts that exotic species have on local biodiversity. In this way the ASPB model identified 7,651 km2 suitable for aquaculture of I. balsanus in its native Balsas basin and 15,633 km¬2 suitable for aquaculture of the non-native I. dugesii. ASPB models were produced for all the studied species. The final results were used to produce a set of guidelines for the development of sustainable aquaculture of native species at catchment level that cover genetic and ecological implications, as well as a well planned decision making tool produced in a GIS.

Ricefield based fish seed production (RBFSP) in irrigated spring (boro) ricefields after initial introductions by external promoters has spread among farmers in parts of Northwest Bangladesh. This approach to producing juvenile fish, rather than by specialised geographically clustered hatchery and nursery enterprises, has been recognised as a strategy for decentralised production that makes large high quality seed available locally and supports food fish production. RBFSP has been promoted by the international NGO CARE as part of a process to improve rice-based livelihoods of farming households using a farmer field school (FFS) approach in two consecutive projects between 1993 and 2005. The approach is technically simple and is based on the stocking of common carp (Cyprinus carpio) eggs and Nile tilapia (Oreochromis niloticus) broodfish in ricefields. As a new approach to farmer level fish seed production, its livelihood impacts on the farming households as well as associated actors; its adoption, adaptation and rejection process in farming households; and its cost-effectives for dissemination at farmer level were not well understood. This thesis mainly applies the concept of the sustainable livelihood approach (SLA) using tools and processes of the growing family of participatory research. A systems approach was used to ensure that the key stakeholders including households, community and extension organizations were included. The study was initiated with a well-being analysis of community households to identify poorer households before exploring impacts of RBFSP on poorer producing households (RF) compared to non-producing (NRF) households based on one-off and longitudinal surveys. Livelihoods impacts on other actors linked directly and indirectly with RBFSP were also investigated. The adoption process of RBFSP at the household level and the cost-effectiveness of its promotion were assessed. Impact studies at the household level showed that RF households were significantly larger and had lower levels of formal education than NRF. Adoption of RBFSP had improved practical skills and hence substantially improved human capital in RF households. RF households tended to have more of their ricefish plots located adjacent to their households. Poor and intermediate adopters had smaller riceplots than better-off households but higher seed production efficiencies (poor-315.1 kg fingerlings/ha; intermediate-419.1 kg fingerlings/ha) than better-off households (294.6 kg fingerlings/ha). In addition to direct consumption of large fingerlings, RF households restocked them for further growth in their household ponds in doing so increasing yields by 60%. Fish consumption increased substantially in RF households based on their own production reducing their dependency on purchase from markets. The year round longitudinal survey revealed that activities for RBFSP were compatible with their existing rice-based agriculture activities for household members including men, women and children. The relatively limited income from fingerling production improved cash flow in the low income months. Consumption of large size fingerlings from ricefields provided nutrient dense food in the ‘hungry gap’ months when supplies of wild fish were poor, smoothing consumption. Apart from RF households, RBFSP extended its livelihoods impacts to a wide range of actors in and around the seed producing community. Poor fry traders were found to be key actors in the spread and support of RBFSP. On average fry traders supplied fingerlings to 35 foodfish producers within a mean distance of 5 Km from producing households in a community where RBFSP was well established. The end users (foodfish producers) included households with their own ponds, ponds with multiple ownership and larger waterbodies leased by small groups. Locally available RFBSP juveniles were attractive to each of these groups, supplementing hatchery derived seed. A large number of complex socio-cultural and technical factors were related to household level adoption of RBFSP. The major factors included use of cash generated to prevent distress sales of rice; lack of requirement to use pesticide in ricefields; meeting the household consumption demand; capacity to restock fingerlings in ponds; lack of any negative effects on rice production; increased non-stocked fish production in riceplots; simplicity of the technology; ease of fish harvest from riceplots; increased ability to gift fingerlings/foodfish to relatives and neighbours; more efficient use of both riceplot and irrigation pumps. The most important reasons for households not attempting or quickly rejecting RBFSP were labour conflicts with other activities. However, lost access to the riceplots through changes in tenure was the most common cause of late rejection by households who had practiced RBFSP for several years after withdrawal of CARE support. Location of fish seed producing plots close to the homesteads facilitated household women to contribute to seed production activities through feeding and looking after fish. Women were able to decide and control resources generated from fingerling sales as well as choosing to gift fingerlings to their relatives. Informal transfer of fingerlings in this way stimulated spread of RBFSP. Decentralised fish seed production was promoted through FFS very cost effectively. The introduction of an improved strain of Nile tilapia (GIFT) broodfish greatly enhanced the returns from decentralised seed production based on common carp alone. High levels of secondary adoption improved benefits from promoting RBFSP. The major benefit derived from the improved returns to food fish farmers using locally produced seed. Higher levels of net present value (NPV) and benefit cost ratio (BCR) were achieved based on promotion of mixed-sex tilapia in RBFSP than mono-sex tilapia produced in a large scale central hatchery. Cost-effectiveness in terms of multiplier development impacts on ramification of secondary adopters and, income of fry traders and foodfish producers, RBFSP also showed better performance than a mono-sex tilapia hatchery.

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

Made available in DSpace on 2017-07-10T18:13:26Z (GMT). No. of bitstreams: 1 Guilherme Wolff Bueno.pdf: 984593 bytes, checksum: b5da2ea5e5a88985033ca0621f4e67fb (MD5) Previous issue date: 2011-02-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The relationship between men and environment has always been marked by anthropocentric logic, in which distinguishes man from nature and is elevated to the title and source of all other values. Under this logic, man has caused many environmental impacts, bringing to society some irreversible damages. However, this view is being increasingly criticized and revised. The global tension facing the responsibility in producing in a sustainable way, given that water resources are limited, drives a new global context, which requires a different way of thinking and acting. Therefore, the activity represented by aquaculture producers and entrepreneurs, feed mills, regulatory agencies, educational and research institutions may establish codes of conduct and environmentally responsible management practices in order to minimize the environmental impacts of animal production. Therefore, the objective of this study consisted of two experiments to determine the environmental impact in the aquatic environment of phosphorus in diets for juvenile Nile tilapia (Oreochromis niloticus). In this context, the first experiment discusses the influence of different levels of phosphorus in the diet and the emission of effluents from the fish culture. We used 120 juvenile O. niloticus with mean weight of 85.11 ± 0.34 g to evaluate two levels (0.8 and 1.2%) of total phosphorus in the diet, to determine the apparent digestibility of phosphorus in the diets using chromic oxide (Cr2O3) incorporated in the rate of 0.1% in the diets. And to verify how the use of different ingredients in the diet will meet the requirements for tilapia and the total phosphorus in wastewater generation, total phosphorus digestibility, pellets stability in water, and minerals leaching in water from the diet were evaluated and quantified the waste generated to produce a ton of tilapia. Six isonitrogenous and isocaloric diets were formulated containing 28% crude protein and 3000 kcal DE / kg with levels of 0.8% of total phosphorus, using dicalcium phosphate, meat and bone meal, poultry offal meal, anchovy meal, tilapia waste and bone meal as ingredients. We conclude that the use of 0.8% of total phosphorus promotes a better control of water quality and can be used as a nutritional strategy for reducing effluent from aquaculture. As for the ingredients, the best efficiency for total phosphorus was 83.74% for dicalcium phosphate, 77.73% for anchovy meal, 75.27% for tilapia meal and 73.42% for poultry meal in diets for juvenile Nile tilapia. Therefore through a balanced animal nutrition is possible to reduce the metabolites excretion in the water, reaching an adequate fish production with less environmental impact. / A relação da humanidade com o meio ambiente sempre foi marcada pela lógica antropocêntrica, na qual o homem distingue-se da natureza e é elevado ao título de fonte de todos os demais valores. Sob tal lógica, os homens provocaram inúmeros impactos ambientais, trazendo para a sociedade atual danos que podem ser irreversíveis. Todavia, tal visão está sendo cada vez mais criticada e revista. A tensão mundial frente à responsabilidade de se produzir com sustentabilidade, uma vez que os recursos hídricos são limitados, impulsiona um novo contexto global, que exige uma maneira diferente de pensar e de agir. Nesta conjuntura, a atividade aquícola representada pelos produtores e empreendedores, fábricas de rações, agências regulatórias, e instituições de ensino e pesquisa podem definir códigos de conduta e práticas de manejo ambientalmente responsáveis de forma a minimizar os impactos ambientais da produção animal. Diante desta problemática, o objetivo deste trabalho consistiu na realização de dois experimentos com o intuito de auxiliar na determinação do impacto ambiental do fósforo total em rações para juvenis de tilápia do Nilo (Oreochromis niloticus) no ambiente aquático. Neste contexto, o primeiro experimento aborda a influência que a utilização de diferentes níveis de fósforo total na dieta possa promover devido à emissão de efluentes oriundos do cultivo de peixes. Utilizaram-se 120 juvenis de O. niloticus com 85,11 ± 0,34 g, com níveis de 0,8 e 1,2% de fósforo total na dieta para a determinação do coeficiente de digestibilidade aparente do fósforo em tilápias, aplicando-se como indicador o óxido crômico (Cr2O3) incorporado na proporção de 0,1% nas dietas. Posteriormente, para verificar a diferença que há no aproveitamento dos diferentes ingredientes utilizados na dieta para atender as exigências de fósforo total para tilápias e consequentemente na geração de efluentes, realizou-se um experimento, onde avaliaram-se a digestibilidade do fósforo total das rações, a estabilidade dos pélets de ração na água, a lixiviação dos minerais da ração durante sua exposição na água e a quantificação de efluentes gerados para produção de uma tonelada de tilápia. Para tanto, formularam-se seis rações isoprotéicas e isoenergéticas contendo 28% de proteína bruta e 3000 kcal de ED/kg com níveis de 0,8% de fósforo total, utilizando como ingredientes o fosfato bicálcico, farinha de carne e ossos, farinha de vísceras de aves, farinha de anchovas, farinha de resíduos de tilápia e farinha de ossos calcinada. Conclui-se que a utilização da dieta com disponibilidade de 0,8% de fósforo total promove o melhor controle da qualidade da água e pode ser utilizada como estratégia nutricional para diminuição de efluentes da aquicultura. Em relação aos ingredientes, a melhor eficiência na utilização do fósforo total foi de 83,74% para o fosfato bicálcico, 77,73% para a farinha de anchova, 75,27% para a farinha de tilápia e 73,42% para farinha de vísceras de aves em rações para juvenis de tilápias do Nilo. Portanto, por meio da nutrição animal é possível minimizar a excreção de metabolitos ao meio aquático proporcionando uma produção com menor impacto ambiental.