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Literatura académica sobre el tema "Extensive fish farming"

Autor: Grafiati

Publicado: 30 de noviembre de 2024

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Artículos de revistas sobre el tema "Extensive fish farming"

Amian, Atsé Franck, Eboua Narcisse Wandan, Melecony Célestin Blé, Adja Ferdinand Vanga y Pierre Joseph Assi Kaudhjis. "Etude Des Determinants Socioeconomiques Et Techniques De La Psciculture Extensive En Cote D’ivoire". European Scientific Journal, ESJ 13, n.º 6 (28 de febrero de 2017): 389. http://dx.doi.org/10.19044/esj.2017.v13n6p389.

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The contribution of fish farming is relatively low in the national consumption of fish products. Yet the country has a significant socio-natural potential, which well valued can reduce fish imports and enhance food security. This study, based on a survey conducted in the two main areas of extensive fish farming (Central West and Southwest), was to analyze the technical and socioeconomic determinants of family fish farming to support the dynamic development of this activity. The results showed that 98% of fish farmers are men of 51 to 60 years old. Most of them are illiterate practicing agriculture as their main activity. Farming infrastructure are usually composed of dams ponds (90%) of 0.25-1.5 ha, and ponds of 0.1 ha. Water was provided either by river (95%) or groundwater (5%). On average most farms are of mall size (3 ha) and were acquired by purchasing lands. Fish farmers mainly practiced mixed farming of Tilapia (Oreochromis niloticus) and Heterotis (Heterotis niloticus). In 60% of the cases, fish farming is associated with rice cultivation practiced in the shallows. Fish were mainly fed with rice bran. An important number of farmers (72%) practiced sexing of in order to improve their yields. Furthermore, 60% of them have a lower production to 6 tons per year, and fish were old between 1500 and 2000 CFA (1 FCFA=0,0014 euros) per kg leading to an average annual income of less than 5 million CFA francs.

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SHINDE, ADITYA. "Design and Manufacturing of Solar Operated Automatic Fish Feeder System". INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, n.º 05 (9 de mayo de 2024): 1–5. http://dx.doi.org/10.55041/ijsrem33180.

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One of the most significant aqua cultural endeavors to date is fish farming. Traditionally, the majority of fish feeding is done by hand, requiring the transportation of people to the feeding location. Fish feeding by hand requires more work, money, and time. Following an extensive survey of farmers across various regions regarding their approaches to fish farming, the Auto Switch Food Feeder, which utilizes new technologies to replace traditional farming methods, will automate farming practices. The design of the solar-powered fish feeder will be based on certain parameters, such as the capacity of the culture tank, stocking density, fish biomass, and feed diameter. Additionally, a user-friendly interface that is compact and convenient for farming will be designed. In the current project, user interface design and timing controls are applied to automate feeding methods, which will significantly save labor costs and efforts while improving the quality of fish feeding. Key Words: Fish Farming, Automatic feeding, automation etc.

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Малыгина, Валентина, Ксения Антошина y Татьяна Гончарова. "О развитии рыбного хозяйства Донецкой Народной Республики путем организации рыбоводства речных рыб". ИЗВЕСТИЯ ДАЛЬНЕВОСТОЧНОГО ФЕДЕРАЛЬНОГО УНИВЕРСИТЕТА. ЭКОНОМИКА И УПРАВЛЕНИЕ, n.º 3 (2020): 87–97. http://dx.doi.org/10.24866/2311-2271/2020-3/87-97.

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В статье раскрыта необходимость развития рыбного хозяйства Донецкой Народной Республики (далее – ДНР) путем организации рыбоводства речных рыб, пояснены причины трансформации потребительского рынка пищевых продуктов в сегменте рыбы и рыбных товаров, приведена характеристика технологий и способов разведения рыбы, проведены расчеты стоимости одного килограмма рыбы, выращенной экстенсивным и полуэкстенсивным способами. The paper discloses the necessity to develop the fisheries in the Donetsk People's Republic by organizing river fish farming, explains the reasons for the consumer food market transformation in the segment of fish and fish products, describes the technologies and methods of the fish farming, calculates the cost of one kilogram of fish raised by extensive and semiextensive methods. Fisheries, as a type of entrepreneurial activity, will not bring instant profit, and even under the best conditions it can be in two to five seasons (it all depends on the growth rate and value of the breed). To have the income every season, with extensive fish farming, fry will have to be launched into the pond every year until the first year’s youngsters become sexually mature and begin to reproduce themselves. To develop the fisheries, a proposal was made to create a laboratory for analyzing and confirming the quality of fish products in the Novoazovsky district, quotas for fishing, issues of amending the existing regulations and developing the new ones in the fisheries, as well as certain aspects of the fishermen interaction with the regulatory authorities and state enterprises.

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Tulli, Francesca, José M. Moreno-Rojas, Concetta Maria Messina, Angela Trocino, Gerolamo Xiccato, José M. Muñoz-Redondo, Andrea Santulli y Emilio Tibaldi. "The Use of Stable Isotope Ratio Analysis to Trace European Sea Bass (D. labrax) Originating from Different Farming Systems". Animals 10, n.º 11 (5 de noviembre de 2020): 2042. http://dx.doi.org/10.3390/ani10112042.

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This study aimed to determine whether isotopic ratio mass spectrometry (IRMS) can discriminate farmed European sea bass according to different farming systems and geographic origins. Dicentrarchus labrax of commercial size from three different rearing systems (concrete tank inland, sea cages, and extensive methods in valleys or salt works) were collected at the trading period (autumn–winter). For each farming type, different locations spread over Italy were monitored. Once the fish were harvested, the muscle and feed were sampled. For both muscle and feed, δ13C and δ15N were measured by continuous flow elemental analyzer isotope ratio mass spectrometry (CF-EA-IRMS) with the goal of discriminating samples based on the rearing system. Additional δ2H and δ18O measurements of fish samples were performed by continuous flow total combustion elemental analyzer isotope ratio mass spectrometry (CF-TC/EA-IRMS) to track the geographical origin. The measurements of δ13C and δ15N made it possible to discriminate cultured sea bass from different farming systems (extensive vs. intensive) reared at different geographical sites in Italy. Additional information was obtained from δ18O and δ2H, which enabled the geographical areas of origin of the sea bass farmed extensively and intensively (in cages) to be distinguished.

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Hungria, Anderson Paixão, Monique Damasceno Pinto, Antônia Rafaela Gonçalves Macedo, Osnan Lennon Lameira Silva, Regiara Croelhas Modesto, Lenilton Alex de Araujo Oliveira, Lian Valente Brandão y Fabricio Nilo Lima da Silva. "Understanding the Abandonment of Aquaculturists: A Case in the Amazon (North of Brazil)". Aquaculture Journal 4, n.º 3 (14 de agosto de 2024): 148–62. http://dx.doi.org/10.3390/aquacj4030011.

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Despite the huge potential of aquaculture in the Amazon, several producers have abandoned the activity due to a lack of assistance, technology, and innovation. Thus, the objective of this study was to identify factors that have contributed to the withdrawal of aquaculturists from the municipality of ‘Vigia de Nazaré’, state of Pará (Northern Region of Brazil). This case study took place in 2022 through a quanti-qualitative survey, applying structured questionnaires to former aquaculturists. A total of 30 fish farms were investigated, with 11 of them being abandoned. They are distributed across 10 rural communities that have developed fish farming, with ‘Vila de Itapuá’ (18.2%) being the most representative. When active, fish farming was practiced by men (100%) aged between 51 to 60 years (54.5%) with an incomplete primary education (100%), who carried out the activity for an average of 5 years (81.8%), quitting fish farming between the years 2019 and 2020 (72.7%). All former aquaculturists owned small properties, with excavated ponds in an extensive system and used family labor. The absence of technical assistance and the high cost of feed were pointed out as the main problems in the production chain. It is worth noting that the monoculture of Tambaqui (Colossoma macropomum) accounted for 63.6% of the species produced in rural communities. In conclusion, former aquaculturists express the desire to return to fish farming due to its socio-economic importance. For this, government actions supporting technical assistance and advanced studies in fish nutrition by educational, research, and extension institutions are necessary.

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Martins, Williane Maria de Oliveira, Márcia Cristina Nascimento Justo, Melissa Querido Cárdenas y Simone Chinicz Cohen. "Seasonality of parasitic helminths of Leporinus macrocephalus and their parasitism rates in farming systems in the Amazon". Revista Brasileira de Parasitologia Veterinária 26, n.º 4 (9 de noviembre de 2017): 419–26. http://dx.doi.org/10.1590/s1984-29612017062.

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Abstract The objective of the present study was to analyze the seasonality of parasitic helminths of Leporinus macrocephalus from fish farms in the municipality of Cruzeiro do Sul, Acre, Brazil, and their parasitism rates. Between June 2014 and March 2015, 200 specimens were sampled from two fish farms: one with a semi-intensive system and the other with an extensive system (100 fish from each farm: 50 during the dry season and 50 during the rainy season). Fifteen species of parasites were found, with seasonal variations of some according to the farming system. In the semi-intensive fish farm, there was greater prevalence of infection during the dry season. Also, Urocleidoides paradoxus, Procamallanus (Spirocamallanus) inopinatus, Goezia leporini and Rhabdochona (Rhabdochona) acuminata presented differences in their parasitism rates between the seasons. In the extensive fish farm, no variation in the prevalence of infection was observed between the seasons and two species Tereancistrum parvus and G. leporini demonstrated differences only regarding the mean intensity of infection. The data presented here may help fish farmers to understand the parasite dynamics of L. macrocephalus in farming systems during the dry and rainy seasons in the state of Acre.

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Kumara, H. K. R. S., K. S. S. Atapaththu, S. S. Herath, N. P. Vidanapathirana y M. M. K. I. Marasinghe. "Exploring Ecological Functions of Rice-Fish Integration in the Agricultural Landscape: A Review to Investigate Feasibility of Implementing Rice-Fish Integration in Sri Lanka". Journal of Agro-Technology and Rural Sciences 3, n.º 2 (7 de junio de 2024): 24–35. http://dx.doi.org/10.4038/atrsj.v3i2.53.

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Rice-fish integration is, a symbiotic farming system where fish are reared in rice fields. Although this farming method widespread in many Asian countries, it is relatively new to Sri Lanka, and consequently information on its ecological functions under Sri Lankan context is scarce. Therefore, detailed investigation on the ecological function of rice fish integration would provide necessary information to establish rice-fish integration in Sri Lanka. This study followed a qualitative case study approach, including literature review and extensive document analysis. The results highlighted the rice-fish integration approach presents an array of ecological functions, underscoring its potential as a sustainable agricultural practice. Ecologically, the presence of fish in the system contributes to increase nutrient availability for rice plants, and biologically control weed and pest. Further, rice-fish integration promotes soil fertility of rice fields which improves growth and nutrient uptake of rice plants. The rice plants, in turn, play a pivotal role to maintain biodiversity in rice fields through water purification, establishing optimal water temperature conditions, and providing an array of micro habitats for a diverse aquatic fauna and flora. On the other hand, rice fish integration promotes water use efficiency, higher economic return and animal protein requirement of local farming communities. Considering ecological, economical and health benefits, integration of tilapia fish with suitable rice varieties available in Sri Lanka is proposed. In conclusion, the rice-fish integration is an ecologically balanced farming system which has a potential to enhance the sustainability of rice field farming systems in Sri Lanka.

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GIRARD, Léo, Alexander WEZEL y Joël ROBIN. "Drying out fish ponds, for an entire growth season, as an agroecological practice: maintaining primary producers for fish production and biodiversity conservation". Open Research Europe 3 (18 de agosto de 2023): 125. http://dx.doi.org/10.12688/openreseurope.16363.1.

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Agroecology largely focusses on terrestrial agroecosystems, but it can also be applied to fish farming. Indeed, ponds are typically used for fish production in Europe, but are also important reservoirs of biodiversity. Numerous studies demonstrate that both fish production and biodiversity are strongly determined by human management. One key practice in extensive fish farming, although more rare in Europe, is to dry out ponds. They are left dry for a complete year after several years of fish production. However, the extent to which this practice affects the functioning of the ecosystem, its biodiversity and fish production remain unclear. We investigated data from 85 fish ponds in the Dombes region, France, sampled between 2007 and 2014. We related variation in key abiotic characteristics to the time since last dry out. The dataset included organic matter content in pond sediments and concentrations of inorganic nitrogen and phosphorus in the water column, and biotic components such as macrophytes cover and richness, phytoplankton concentration and richness, macroinvertebrates density, and fish yield. Our results show that drying out facilitates the mineralization of organic matter in sediments and results in higher concentrations of inorganic nitrogen in the water column. Macrophytes cover is highest during the first year after drying out, and gradually declines after at the expense of increasing phytoplankton concentration. The diversity of both is highest in the first year after drying out and declines rapidly, especially for macrophytes. Fish yield is at its maximum in the second year. Drying out fish ponds appears to be an important agroecological practice in extensive fish farming with an application every three to four years. By nutrient recycling, this practice has a positive impact on the balance between primary producers and indirectly on the whole food web during two years. It optimizes fish production and allows biodiversity conservation.

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GIRARD, Léo, Alexander WEZEL y Joël ROBIN. "Drying out fish ponds, for an entire growth season, as an agroecological practice: maintaining primary producers for fish production and biodiversity conservation". Open Research Europe 3 (15 de octubre de 2024): 125. http://dx.doi.org/10.12688/openreseurope.16363.2.

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Pilin D.V., Tumenov A.N., Tuleuov A.M., Oskina A.A., Bulekov N.U. y Dnekeshev A.K. "Use of data on zoobenthos reserves of fishless reservoirs to assess potential production of bentophage fish similar small reservoirs of north-west Kazakhstan". Novosti nauki Kazahstana, n.º 3 (30 de septiembre de 2022): 39–45. http://dx.doi.org/10.53939/15605655/2022_3_39.

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The potential fish productivity of four fishless reservoirs of Western Kazakhstan is estimated for subsequent use in fish farming calculations on similar fishery reservoirs of the region. Potential fish production was determined by the biomass of feed zoobenthos. In parallel the productivity of carp as main object of extensive aquaculture was evaluated in the lake-commercial fish farms. The obtained values of potential fish production in the reservoirs deprived of ichthyofauna equaled to 72 kg per ha for the reservoirs of West Kazakhstan and 37 kg per ha for the Aktobe region. The productivity of carp grown in extensive aquaculture in the West Kazakhstan region in the first year of cultivation amounted to 75 kg per ha.

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Tesis sobre el tema "Extensive fish farming"

Girard, Léo. "Étangs piscicoles et services écosystémiques : Relations entre pratiques de gestion, maintien de la biodiversité et stockage de carbone". Electronic Thesis or Diss., Paris, AgroParisTech, 2024. http://www.theses.fr/2024AGPT0008.

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L'Europe renferme de nombreux paysages d'étangs, pour beaucoup avec une origine pouvant remonter au Moyen-âge et une vocation historique de production piscicole. Ces milieux, malgré qu'ils soient anthropisés, sont connus pour leur capacité à présenter une biodiversité importante, avec des espèces rares, voir endémiques ou menacées. Avec l'abandon de la pisciculture, combiné à d'autres menaces comme le changement climatique, un nombre significatif de ces étangs ont disparus au cours des dernières décennies. Jusqu'à récemment, et ce malgré le rôle important qu'ils peuvent jouer, ces petits plans d'eau ont de plus été négligés en Recherche, mais également par les politiques publiques.Dans ce travail de thèse nous nous sommes intéressés aux effets de différentes pratiques de gestion piscicoles sur certains services écosystémiques rendus par les étangs piscicoles. Dans un premier temps, nous avons analysé la pratique de l'assec et ses impacts à la fois sur la biodiversité et sur la productivité en poissons. Dans un second temps, nous avons exploré les impacts de différentes gestions de la densité piscicole sur les caractéristiques des communautés de macrophytes. Et enfin, nous avons étudié les étangs piscicoles comme potentiels puits ou sources de carbone, et les effets des pratiques de gestion sur ces bilans carbone.Pour compléter les connaissances scientifiques sur ces thématiques, nous avons capitalisé sur des données historiques collectées en Dombes (Ain, France) depuis 2007, mais également sur des données collectées dans le cadre du projet européen PONDERFUL, entre 2021 et 2022, en Dombes et dans le Midden-Limburg (Belgique). Nous avons analysé à la fois des données sur la physico-chimie de l'eau et des sédiments, ainsi que des données de biodiversité (macrophytes, phytoplancton et macroinvertébrés), de stockage et d'émissions de carbone, ainsi que sur les pratiques de gestion piscicoles (distance au dernier assec, empoissonnage, fertilisation).Nos résultats démontrent que l'assec constitue une pratique agroécologique majeure pour la pisciculture extensive en étang. Cet assèchement volontaire favorise la recolonisation des macrophytes ainsi que leur diversité lors de la remise en eau. La deuxième année en eau est caractérisée par un “état instable” d'équilibre entre les deux producteurs primaires. Cet état apparait comme étant favorable à la fois à la biodiversité, à la production mais également au stockage du carbone. L'intensification de la production, à travers une augmentation des densités piscicoles, a néanmoins des effets négatifs sur la richesse spécifique des macrophytes. Elle impacte également la structure des communautés. Les étangs piscicoles possèdent des sous-ensembles d'espèces, nichés dans les communautés plus riches des étangs gérés sans poissons. Nous avons également pu montrer une très forte variabilité sur les bilans carbone réalisés sur 20 étangs piscicoles. En moyenne, les étangs monitorés apparaissent comme étant plutôt des puits de carbone, à hauteur d'environ 4 tonnes de CO2 équivalent stocké par hectare et sur 6 mois. La phase d'assec est quant à elle caractérisée par des émissions de gaz à effet de serre importantes.Tous ces éléments permettent de confirmer que les étangs piscicoles, associés à des pratiques extensives, peuvent fournir de nombreux services écosystémiques. La production piscicole n'est pas antinomique de la conservation de la biodiversité. La pérennité de ces milieux dans les paysages européens, et des services fournis, passe par le maintien de ces pratiques de gestion. Même si concilier les services d'approvisionnement et de support semble possible, à l'avenir, une hiérarchisation des services souhaités sera nécessaire, notamment au regard des effets inverses que peuvent avoir certaines pratiques de gestion
Europe is home to a large number of “pond landscapes”, many with origins dating back to the Middle Ages and a historic vocation for fish farming. Despite their man-made nature, these environments are known for their capacity to harbor significant biodiversity, with rare, even endemic or endangered species. With the abandonment of fish farming, combined with other threats such as climate change, a significant number of these ponds have disappeared in recent decades. Until recently, and despite the important role they can play, these small water bodies have been neglected in research, but also in public policies.In this PhD thesis work, we looked at the effects of different fish farming management practices on ecosystem services provided by fish ponds. First, we analyzed the practice of drying-out ponds and its impact on both biodiversity and fish yields. Secondly, we explored the impacts of different fish density management on macrophyte community characteristics. And finally, we studied fish ponds as potential carbon sinks or sources, and the effects of management practices on these carbon balances.To contribute to the scientific knowledge on these topics, we capitalized on historical data collected in the Dombes region (Ain, France) since 2007, but also on data collected as part of the European PONDERFUL project, between 2021 and 2022, in Dombes and Midden-Limburg (Belgium). We analyzed data on water and sediment physico-chemistry, as well as biodiversity (macrophytes, phytoplankton and macroinvertebrates), carbon storage and emissions, and fish farming management practices (time since the last dry year, fish stocking, fertilization).Our results show that drying-out is a major agroecological practice for extensive pond fish farming. This voluntary draining facilitates the recolonization of macrophytes and their diversity when the pond is re-watered. The second year in water is characterized by an "unstable state" of equilibrium between the two primary producers. This state appears to be favorable to biodiversity, production and carbon storage. Intensification of production, through increased fish densities, nevertheless has negative effects on macrophyte species richness. It also impacts community structure. Ponds used for fish farming have subsets of species that nest in the richer communities of ponds managed without fish. We were also able to show a very high degree of variability in the carbon balances of 20 fish ponds. On average, monitored ponds appear to be carbon sinks, with around 4 tonnes of CO2 equivalent stored per hectare over 6 months. The dry year, on the other hand, is characterized by high greenhouse gas emissions.All these elements confirm that fish ponds, combined with extensive practices, can provide numerous ecosystem services. Fish production is not incompatible with biodiversity conservation. The sustainability of these environments in European landscapes, and of the ecosystem services they provide, depends on the maintenance of these management practices. Even if it seems possible to reconcile provisioning and support services, in the future it will be necessary to establish a hierarchy of desired services, particularly in view of the inverse effects that certain management practices may have

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Libros sobre el tema "Extensive fish farming"

Mahida, Navghan. Differences Between Intensive and Extensive Fish Farming. Arcler Education Inc, 2023.

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Mahida, Navghan. Differences Between Intensive and Extensive Fish Farming. Arcler Education Inc, 2022.

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Sharma, Shruti, Akhilesh Gaur y Anil Bisht. Handbook on Fish Farming : (an Extension to Present Fish Farming Tools & Techniques). Independently Published, 2019.

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Capítulos de libros sobre el tema "Extensive fish farming"

Oswald, Marc. "Extensive Fish Farming, a Complementary Diversification of Plantation Economies". En Economics and Ecology of Diversification, 201–24. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-7294-5_9.

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Adeleke, M. L., D. Al-Kenawy, A. M. Nasr-Allah, M. Dickson y Desalegn Ayal. "Impacts of Environmental Change on Fish Production in Egypt and Nigeria: Technical Characteristics and Practice". En African Handbook of Climate Change Adaptation, 789–805. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_153.

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AbstractA survey approach was applied to examine the technical characteristics of fish farming practice in Egypt and Nigeria. Critical issues such as floods and other vices were considered in bringing out the inference and level of aquaculture in both countries. Multistage sampling technique was used to select the study area and the number of respondents. Both primary and secondary data were used in the analysis. Eighty fish farmers were randomly selected from each of the country, making a total of 160 respondents. The socioeconomic characteristics revealed that aquaculture is an antique venture in Africa with Egypt taking the lead, i.e., 99% of the respondents practice in large-scales production of more than 11 Fadden/acre per, and 100% males depend mainly on agricultural drainage water for their earthen ponds. Ninety-eight percent cultured tilapia (Oreochromis niloticus) which was believed to have originated from the Nile River. In terms of financial performance and partial economic analysis, tilapia production commands more sales in Egypt, while catfish (Clarias) production is seen as a promising venture in Nigeria. The fish farmers have various perceptions and reactions toward environmental changes factors such as cost of labor/manpower and inputs, poor water quality, and fish extension services, and climate change impedes aquaculture development in the countries. To achieve the scale of aquaculture expansion as observed in Asian and other developed part of the world, efforts should be geared toward continental and regional integration in order to encourage aquaculture practices in Nigeria and other parts of Africa. More so, government intervention and incentives should be paramount in Egypt to reduce the excessive exploitation of the private input suppliers.

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Matthews Mbokane, Esau, Lucia Matlale Mbokane, Seraku Samuel Motimele y Samkelisiwe Nosipho Hlophe-Ginindza. "Successes and Challenges of Catfish Farming in the Small-Scale Industry in Southern Africa". En Catfish - Advances, Technology, Experiments [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106380.

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This chapter summarizes the successes and challenges of catfish farming in the small-scale industry in Southern Africa. Given that capture fisheries have been declining steadily over the years in many countries, aquaculture is generally expected to grow to meet demand. However, catfish production in most Southern African countries is low. This is despite the region having the most suitable temperature for the culture of freshwater fish species. In Southern Africa, catfish farming is one of the most important components of inland aquaculture, and it is mainly dominated by the small-scale sector. Production in the small-scale sector is affected by several constraints, which affect the profitability of the sector. These challenges include, among others, quality of production systems, supply of quality fingerlings, feeds, management of diseases, education and training of farmers, marketing and development of products, access to finance, research capacity, extension services, and, to some extent, regulatory frameworks and policies. The chapter proposes interventions that are needed to improve the production of catfish in Southern Africa. For instance, there is a need for the small-scale sector to move from intensive to advanced culture systems, such as recirculating aquaculture systems and integrated aquaculture systems, such as aquaponics, in order to boost catfish production.

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Jeffrey*, S. W., M. R. Brown* y J. K. Volkmant†. "Haptophytes as feedstocks in mariculture". En The Haptophyte Algae, 287–302. Oxford University PressOxford, 1994. http://dx.doi.org/10.1093/oso/9780198577720.003.0015.

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Abstract Mass-cultured microalgae, including haptophytes, are used extensively in mariculture as live feeds for all growth stages of molluscs, for the early larval stages of crustaceans and fish, and for brine shrimp and rotifers that are animal intermediates in mariculture food chains. Temperate strains of Pavlova, and temperate and tropical strains of Isochrysis have been used successfully worldwide for oyster and mussel farming since the 1950s. Microalgae must supply a balanced mixture of key nutrients. As part of a study of the nutritional (biochemical) composition of about 40 species of both classical and new isolates of microalgae from six algal classes, we have identified seven strains of haptophytes from the genera Pavlova and Jsochrysis which show excellent nutritional profiles for larval animals. Grown under both standard laboratory and hatchery conditions they show good profiles of total protein, carbohydrate, and lipid (gross composition), they are rich in essential and non-essential amino acids, and they have significant concentrations of essential polyunsaturated fatty acids. Haptophytes are also rich in B, C, D, and K vitamins. The cells are easily assimilated by larval animals because of their small size (3-8 µ,m) and absence of a tough cell wall. Other attributes include fast growth rates, easy mass-culture, wide temperature and salinity tolerances, and absence of toxins. The nutritional attributes of haptophytes studied in our laboratories will be described in this paper.

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"efficiency. By measurements of total odour strength in a treatment plant the ED values pointed out the sludge press and dewatering process as the predominant odour sources of the plant. In the venting air from this position extremely high ED values were recorded. This air was led through a carbon filter for odour reduction. Olfactometric measurements at the filter revealed poor odour reducing efficiency. It was observed that odour compounds were not destroyed in the filter. They only restrained until the carbon became saturated, and thereafter evaporated into the outlet air contributing to the odour strength. The filter capacity was obviously too small for the heavy load. Attempts to reduce the odour strength before the filter did not succeed, until the air was led through a container filled with saturated lime slurry (pH = 12-14). The slurry was part of a precipitation process in the plant. Dispersion in the alkaline slurry extensively reduced the odour strength of the air, resulting in sufficient capacity of the carbon filter also when handling heavy loads of sewage sludge. Since then the carbon filter has worked well, within the limitation of such filters in general. Neither is it observed signs indicating reduced precipitation properties of the lime slurry. Measurements of total odour strength in combustion processes imply sampling challenges. Beside the chemical scrubber process, combustion of odorous air is the best odour reducing method. The disadvantage of this process is the high energy costs. Treatment at apropriate conditions, however, will destroy the odorous compounds extensively. Temperatures about 850 C and contact time up to 3 seconds are reported (2,3). Olfactometric measurements in combustion processes involve certain sampling problems caused by the temperature difference between inlet and outlet. The humidity of outlet air must also be taken into consideration. Problems may occur when hot outlet air is sampled at low temperatures. In most such cases sampling is impossible without special arrangements. Such conditions are present during odour measurements in fish meal plants with combustion as the odour reducing method. The largest problem turned out to be the temperature differences between outlet air (85-220 C) and outdoor temperatures (0-15 C), causing condensation. The dew point of the outlet air was calculated, and experiments were carried out with dilution of the outlet air to prevent condensation in the sampling bags. Condensation was prevented by diluting the outlet air 5-150 times with dry, purified N gas. Comparison of N -diluted and undiluted samples revealed large differences in ED value. In samples demanding a high degree of dilution to prevent condensation, the measured odour strength was up to 5 times higher than in the undiluted corresponding samples. Samples demanding less dilution showed less deviating results. 4. CONCLUSIONS In the attempt to minimize odour emission, olfactometric measurements of total odour strength give useful informations about the odour reducing efficiency of different processes as a function of parameters like dosage of chemicals in scrubbers, humidity and temperature in packed filters, flow rates, etc. Olfactometric measurements also point out the main odour sources of the plant. From a set of olfactometric data combined with other essential". En Odour Prevention and Control of Organic Sludge and Livestock Farming, 98. CRC Press, 1986. http://dx.doi.org/10.1201/9781482286311-34.

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Actas de conferencias sobre el tema "Extensive fish farming"

Cruz, Francis Cedric, Kamran Mahmudov, Andreas Marouchos y Amy Bilton. "A Feasibility Study on the Benefits of Feedback Aerator Control in Precision Aquaculture Applications for the Developing World". En ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-98087.

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Abstract Aquaculture is a growing source of food and income for many in the developing world. In developing countries, where more than 18 million people engage in aquaculture, yields have been low due to lacking infrastructure. Aeration has been shown to improve dissolved oxygen (DO) and increase yields, but its use has been low in many developing world environments due to high operating costs. Even when used, they are operated in an ad-hoc manner, resulting in higher than required costs. A potentially more effective implementation is the use of feedback control to maintain adequate DO and increase energy savings. To demonstrate the potential, a feasibility study was conducted comparing the energy consumption of a diffused aeration system, with and without the use of a feedback control system. The effect of the diffused aeration system was simulated for a 100 m3 pond in Bangladesh for extensive and intensive fish farming. The interaction between the aerators and the pond was simulated on ANSYS FLUENT and was used with a DO model to predict the oxygen dynamics of the pond. Results indicated that the addition of a feedback control system could result in 78.66%, and 52.48% in energy cost savings compared to continuous operation for extensive and intensive fish farming respectively. Further work in smart instrumentation has the potential to decrease the energy requirements of aeration technologies and improve production for farmers in the developing world.

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Pal, Saptarshi y Chengi Kuo. "Feasibility of Repurposing Offshore Decommissioned Gas Rigs into Fish Farms". En SPE Offshore Europe Conference & Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205446-ms.

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Abstract In the past 70 years the world has relied extensively for its energy needs based on hydrocarbons produced significantly offshore. In recent years many installations with fixed platforms and pipelines are reaching the end of their useful life and are required by law to be decommissioned and removed if an approved alternative use cannot be found. This process coincides with focus on decarbonization arising from global warming and climate change. The conventional way of decommissioning is to remove the structure and take it onshore for disposal. Such an activity costs around £28 million for smaller UKCS installations in the Southern North Sea. Possible alternative solutions include their use as a research-leisure complex and artificial reef. Such an approach would have less impact on the environment and it is therefore worthwhile to explore the feasibility of repurposing these decommissioned UKCS platforms. The paper begins by highlighting the background to UKCS offshore decommissioning and farming fish life-cycle. This is followed by a critical review of the three options of total and partial removals and leave-on-site. It is found that repurposing decommissioned platforms for aquaculture farm has not been given sufficient attention and thus offers scope for a project to explore the feasibility of such a solution. Existing offshore fish farming in various countries are examined before using a decision-making matrix to select the most suitable UKCS installation for conversion and this led to using a normally unattended gas platform for the case study. The focus for this paper is on design and operation of an unattended fish farm and its cost benefit analysis. The former covers fish cage selection, capacity calculation, fish handling procedures, fish feed characteristics, feed demand, designing feed logistics and storage system. The processing facilities are layout on two decks and power needs are generated using a hybrid system of diesel and Li-ion battery. The possibility of using renewable sources by connecting to wind energy grids was also considered. For the latter capital and operating expenditure, revenue generated and maintenance costs are estimated before performing net present value prediction of the profitability of the fish farm over 10 years with for example up to 8 cages and three discount rates. The main conclusions derived are: It is technically feasible to convert a decommissioned gas platform to a fish farm and the operation can be economic. However, liability transfer implications in a repurposed offshore decommissioned gas platforms to fish farms were not established to verify the project viability. The conversion of unattended offshore gas platforms in the UKCS to an automated offshore fish farm is a novel solution which has not been implemented in the North Sea before. The work will provide an economic and environmental friendly solution to decommissioning offshore platforms and provide with a possible profitable investment.

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Thomassen, Paul E. y Bernt J. Leira. "A Prototype Tool for Analysis and Design of Floating Fish Cages". En ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67383.

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Floating fish cages are the main means of production in the multi billion euro salmon farming industry. Despite its pivotal role in production safety, protection of values, as well as in protection of the environment, neither verified structural design procedures nor computer tools for structural analysis and design have received much attention. To a large extent they can be regarded as not being in accordance with the current state-of-the-art of structural analysis and design of slender marine structures. A momentum to move towards a more scientific based design approach has been created by the requirements of the recently introduced Norwegian certification criteria and the accompanying design code NS 9415. A prototype for analysis and design of floating fish cages has been developed and is described herein. The tool is based on an object-oriented framework for general FE analysis. The framework has among other things been developed with ease of extensibility for the software developer in mind. The prototype is thus intended for iterative extension of the functionality. In the first development iteration, described here, the FE framework has been extended, with hydrodynamic load models and a user interface for analysis of floating fish farms. The development of the prototype shows that by building on an object oriented FE framework, specialized and focused applications for aquaculture can be developed with limited effort. As an example analysis — and a possible benchmark — a simplistic model of a steel frame is chosen. Comparison of results obtained with different load formulations indicated that the buoyancy load was more important than the hydrodynamic load.

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Informes sobre el tema "Extensive fish farming"

Breewood, Helen y Tara Garnett. Meat, metrics and mindsets: Exploring debates on the role of livestock and alternatives in diets and farming. TABLE, marzo de 2023. http://dx.doi.org/10.56661/2caf9b92.

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Should we eat meat, eggs, dairy and other animal-sourced foods? If so, how should we produce them and how much should we eat? If not, what should we eat instead? These are just some of the more contentious debates about the future of food systems. This short briefing paper summarises some of the key debates about livestock and its alternatives and describes both the arguments and the evidence underpinning different points of view. We look both at foodstuffs (meat, fish, plants and new foods based on cells grown in bioreactors) and farming methods (both intensive and extensive) with regards to discussions about their environmental, health and social impacts. In so doing, we explore the assumptions and values that often lead stakeholders to differing conclusions about what a sustainable food system looks like.

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Funkenstein, Bruria y Cunming Duan. GH-IGF Axis in Sparus aurata: Possible Applications to Genetic Selection. United States Department of Agriculture, noviembre de 2000. http://dx.doi.org/10.32747/2000.7580665.bard.

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Many factors affect growth rate in fish: environmental, nutritional, genetics and endogenous (physiological) factors. Endogenous control of growth is very complex and many hormone systems are involved. Nevertheless, it is well accepted that growth hormone (GH) plays a major role in stimulating somatic growth. Although it is now clear that most, if not all, components of the GH-IGF axis exist in fish, we are still far from understanding how fish grow. In our project we used as the experimental system a marine fish, the gilthead sea bream (Sparus aurata), which inhabits lagoons along the Mediterranean and Atlantic coasts of Europe, and represents one of the most important fish species used in the mariculture industry in the Mediterranean region, including Israel. Production of Sparus is rapidly growing, however, in order for this production to stay competitive, the farming of this fish species has to intensify and become more efficient. One drawback, still, in Sparus extensive culture is that it grows relatively slow. In addition, it is now clear that growth and reproduction are physiological interrelated processes that affect each other. In particular sexual maturation (puberty) is known to be closely related to growth rate in fish as it is in mammals, indicating interactions between the somatotropic and gonadotropic axes. The goal of our project was to try to identify the rate-limiting components(s) in Sparus aurata GH-IGF system which might explain its slow growth by studying the ontogeny of growth-related genes: GH, GH receptor, IGF-I, IGF-II, IGF receptor, IGF-binding proteins (IGFBPs) and Pit-1 during early stages of development of Sparus aurata larvae from slow and fast growing lines. Our project was a continuation of a previous BARD project and could be divided into five major parts: i) obtaining additional tools to those obtained in the previous project that are necessary to carry out the developmental study; ii) the developmental expression of growth-related genes and their cellular localization; iii) tissue-specific expression and effect of GH on expression of growth-related genes; iv) possible relationship between GH gene structure, growth rate and genetic selection; v) the possible role of the IGF system in gonadal development. The major findings of our research can be summarized as follows: 1) The cDNAs (complete or partial) coding for Sparus IGFBP-2, GH receptor and Pit-1 were cloned. Sequence comparison reveals that the primary structure of IGFBP-2 protein is 43-49% identical to that of zebrafish and other vertebrates. Intensive efforts resulted in cloning a fragment of 138 nucleotides, coding for 46 amino acids in the proximal end of the intracellular domain of GH receptor. This is the first fish GH receptor cDNA that had been cloned to date. The cloned fragment will enable us to complete the GH - receptor cloning. 2) IGF-I, IGF-II, IGFBP-2, and IGF receptor transcripts were detected by RT-PCR method throughout development in unfertilized eggs, embryos, and larvae suggesting that these mRNAs are products of both the maternal and the embryonic genomes. Preliminary RT-PCR analysis suggest that GH receptor transcript is present in post-hatching larvae already on day 1. 3) IGF-1R transcripts were detected in all tissues tested by RT-PCR with highest levels in gill cartilage, skin, kidney, heart, pyloric caeca, and brain. Northern blot analysis detected IGF receptor only in gonads, brain and gill cartilage but not in muscle; GH increased slightly brain and gill cartilage IGF-1R mRNA levels. 4) IGFBP-2 transcript were detected only in liver and gonads, when analyzed by Northern blots; RT-PCR analysis revealed expression in all tissues studied, with the highest levels found in liver, skin, gonad and pyloric caeca. 5) Expression of IGF-I, IGF-II, IGF-1R and IGFBP-2 was analyzed during gonadal development. High levels of IGF-I and IGFBP-2 expression were found in bisexual young gonads, which decreased during gonadal development. Regardless of maturational stage, IGF-II levels were higher than those of IGF-L 6) The GH gene was cloned and its structure was characterized. It contains minisatellites of tandem repeats in the first and third introns that result in high level of genetic polymorphism. 7) Analysis of the presence of IGF-I and two types of IGF receptor by immunohistochemistry revealed tissue- and stage-specific expression during larval development. Immunohistochemistry also showed that IGF-I and its receptors are present in both testicular and ovarian cells. Although at this stage we are not able to pinpoint which is the rate-limiting step causing the slow growth of Sparus aurata, our project (together with the previous BARD) yielded a great number of experimental tools both DNA probes and antibodies that will enable further studies on the factors regulating growth in Sparus aurata. Our expression studies and cellular localization shed new light on the tissue and developmental expression of growth-related genes in fish.

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