3,454 research outputs found
Culture of fish in rice fields
No full textRice is presently grown in 113 countries. Rice farming also offers a suitable environment for the culture of fish and other aquatic organism. This publication synthesizes the available information on the role that aquaculture can play in rice-based farming systems towards food security and poverty alleviation. The review describes the history behind integrating aquaculture with different rice ecosystems, the various production systems in operation such as concurrent, rotational and alternate, the modifications needed to the fields in order to integrate fish with rice farming, and the agronomic and aquaculture management that is necessary. The benefits of integration to communities - economic and environmental - are also described with reviews of the experiences from values countries. The real impacts of rice-fish farming and its future potential in terms of improved income and nutrition are significant but generally underestimated and undervalued. Notable changes have taken place in pest management in rice farming, and in fish seed production and availability making this a particularly relevant moment for emphasizing the importance of rice-fish farming. There is considderable potential for rice-fish farming to expand further in many countries and to contribute substantially towards global food and nutritional security.Freshwater fish, Fish culture
Household socioeconomics, resource use and fish marketing in two thanas of Bangladesh
No full textThis is a report of a socioeconomic survey carried out on a sample of households from owners and operators of small waterbodies in two subdistricts in Gazipur, Bangladesh, to find out the benefits of aquaculture if introduced there. The findings indicate that improved aquaculture technology will benefit the owners and operators of the small water bodies, and that low-cost technologies for aquaculture must be promoted among poor and landless people in order for them to adopt aquaculture.Household surveys, Socioeconomics, Sociological aspects, Fish culture, Fishery economics, Fish consumption, Marketing, Bangladesh,
Detergency in Liquid CO2
No full textIn this dissertation we study Detergency in liquid Carbon Dioxide. Detergency is the cleaning performance of additives, surfactants in particular, in washing fluids. Liquid CO2 is under consideration, for environmental and toxicological reasons, to replace perchloro-ethylene as the solvent in textile dry cleaning technology. Inherent problems of such a transition were confronted with the methodology of chemical engineering design. The Basic Cycle of Design (BCD) approach was used as a pathway for designing a detergent. The BCD also establishes the structural framework of the thesis, which can, therefore, be read as records from a successful product engineering project, in which an effective detergent has been designed for a new dry cleaning solvent. The Dynamic Detergency Model (DDM), which succeeds to explain the role of surfactants in the washing operation, is used as a rational starting point for the design of a detergent in liquid CO2. According to this model, such a surfactant must be: sparingly soluble in the solvent, surface-active and able to form micelles in the solution. The different experiments carried out (solubility, interfacial-tension and dye solubilisation measurements), show that a number of molecules of the homologous polyoxyethylene/alkane series, generally described by the shorthand formula CiEj did indeed behave as surfactants and can be then considered detergents for liquid CO2. In the technical evaluation of the detergents, at laboratory as well as at semi-pilot scale, high washing performances were obtained. They are, indeed, as good for dry cleaning textiles as the present perchloro-ethylene (Perc) technology.Applied Science
Sustainable fish production in Lake Nasser: ecological basis and management policy
No full textThe aim of the Lake Nasser Project is to integrate social, economic, and ecological factors in the formulation of a management policy for sustainable fish production. The workshop was held to review the present state of knowledge, identify constraints, evaluate existing information and state of the art techniques, and determine future research objectives and strategy.Lake fisheries, Fishery management, Artificial lakes, Nasser Lake, Egypt, Arab. Rep.,
Biology and potential impacts of rudd (Scardinius erythrophthalmus L.) in New Zealand
No full textRudd (Scardinius erythrophthalmus) is a cyprinid fish native to Europe that was illegally introduced into New Zealand in 1967. Between the 1960s and 1980s rudd were illegally spread to a number of lakes, ponds, and rivers in New Zealand, principally from the Waikato north. They now also occur in the Wanganui, Manawatu, Nelson, and Canterbury regions. Rudd undergo
ontogenetic changes in diet as they grow. Young-of-the-year rudd (58–65 mm mean fork length (FL)) ate a mixture of planktonic cladocerans and chironomid pupae, and potentially competed for these foods with common smelt (Retropinna retropinna). Larger rudd (100–149 mm FL) were primarily benthivorous, and potentially competed with perch (Perca fluviatilis) of the same size, brown bullhead catfish (Ameiurus nebulosus), and probably common bullies (Gobiomorphus cotidianus). Rudd of still larger sizes were
increasingly herbivorous, until at >200 mm FL their diet was >80% plant material. As rudd prefer native species of aquatic macrophytes to the introduced species, they can probably modify native plant communities and aid the invasion of introduced aquatic weeds. They may also have contributed to
the switch of Hamilton Lake from a macrophyte-dominated state to a phytoplankton-dominated state. It is time for the threats posed by rudd to be recognised, and for an education campaign to be mounted. As past rudd introductions have been done outside the law, increasing the severity of penalties for further illegal transfers is unlikely to be effective, and the coarse angling community should instead be included in management decisions concerning rudd
'Her Irish Heritage' : Annie M.P Smithson and autobiography
No full textThis paper examines some aspects of the work of Annie M.P. Smithson, the author of 21 romance novels between 1917 and 1946. Her attitudes towards women, religion and politics are explored, and the importance of autobiography in her fiction discussed.Cet article analyse divers aspects de l'oeuvre d'Annie M.P. Smithson, l'auteur de vingt et un romans 'romanesques' publiés entre 1917 et 1946. Il étudie son attitude concernant les femmes, la religion, la politique, ainsi que le rôle de l'autobiographie dans sa fiction.Walsh Oonagh. 'Her Irish Heritage' : Annie M.P Smithson and autobiography. In: Études irlandaises, n°23-1, 1998. pp. 27-42
Predicting food consumption and production in fish populations : allometric scaling and size-structured models
No full textLife-history traits in fish populations are highly correlated. A subset of these correlations are called allometric scaling, they refer to biological processes which can be described using body size as independent variable. Particularly, allometric scaling related with food consumption (Q) and biomass production (P) has gained the attention of ecologists for several decades. This thesis proposes a quantitative framework for food consumption, which allows both the identification of the mechanisms underlying the allometric scaling for Q and the development of a predictive model for consumption to biomass ratio (Q/B) in fish populations. This thesis is based on the fact that food consumption can be inferred from first principles underlying the von Bertalanffy growth model. In addition, it has been noticed in the literature that biomass production and food consumption show similar allometric scaling dependence, therefore, both can be derived from these first principles. Thus, a similar quantitative framework was used to produce models for P/B in fish populations. Once functional forms for production and food consumption were identified, a third model was developed for the ratio between production and consumption (P/Q). This ratio is usually named ecological efficiency because it determines how efficiently a population can transform ingested food into biomass. Several authors have noticed that P/Q remains invariant (independent of body size) across species. From a theoretical point of view, the results presented here allow the first quantitative explanation for the existence of the allometric scaling for Q/B and the invariance of P/Q across fish species. These results, together with the explanation for allometry in P/B reported in the literature, suggest that the regular across-species pattern for the trio {P/B,Q/B,P/Q} can be explained by basic principles that underpin life-history in fish populations. This quantitative framework for the trio {P/B,Q/B,P/Q} is based on an explicit dependence with body size, which simplifies the estimation of these quantities. Model complexity depends, in part, on which data are available. Models were applied to real data from commercially important species fished in Chile. Statistical properties of the new models were evaluated by an intensive resampling approach. The simplest possible model for the trio {P/B,Q/B,P/Q} rests on the assumption of a stable age distribution. These quantities have a key importance in ecosystem modelling because they determine population energetics in terms of food intake by predation and the transformation of this energy into population biomass of predators. Application of the new models produces results which were comparable to those given by standard methods. This thesis is a result of multidisciplinary research which attempts to make a contribution to the understanding of the mechanisms underlying the allometric scaling of food consumption and production in fish populations. It proposes models for the trio {P/B,Q/B,P/Q} and thus, has the potential to be widely applicable in fisheries science
Il ruolo della linguistica in un'iniziativa di internazionalizzazione
No full textThe author deals with the role of linguistic sciences and language teaching in the internationalization project of an e-learning Specialization Course
Seasonal variation in horizontal and vertical structure of larval fish assemblages off south-western Australia, with implications for larval transport
No full textThe coastal ocean off south-western Australia is characterised by the southward-flowing Leeuwin Current, which suppresses the upwelling typically associated with other eastern boundary currents in the southern hemisphere. This results in a unique environment for the transport and survival of planktonic fish larvae. The horizontal and vertical structure of larval fish assemblages off south-western Australia was investigated during winter (August 2003) and summer (January 2004), and related to these unusual regional oceanographic and biological processes. Larval fish were sampled along a four station transect running from the inner continental shelf to offshore waters, using depth-integrated bongo net tows and depth-stratified EZ net tows. The distribution of taxa across the shelf and offshore was strongly influenced by the current regime at the time of sampling. Larval fish assemblage structure reflected the distinctive oceanographic conditions found during each season, and vertical depth distributions of larvae affected their horizontal location. Continental shelf samples were dominated by larvae of pelagic fishes, such as clupeiform species (e.g. Sardinops sagax), whereas offshore assemblages were characterised by larvae of oceanic families, such as Myctophidae and Phosichthyidae. The winter cruise (August 2003) was completed during a time of strong, southerly Leeuwin Current flow, whereas the northward-flowing Capes Current, in combination with surface offshore Ekman transport, predominated during summer. The vertical depth preferences of larvae were particularly influential in affecting their horizontal position; especially so for surface-dwelling larval fishes found during summer. This study represents the first documentation of the vertical structure of ichthyoplankton assemblages in the oligotrophic waters off south-western Australia
Socioeconomics of rice-aquaculture and IPM in the Philippines: synergies, potential and problems
No full textRice farming covers nearly one-third of the arable land of Asia. The study shows results that are useful for policymakers wishing to promote new diversification opportunities in the crop sector. It describes some of the complexities in understand farming households and farm labor use and how people make decisions on what crops to grow, how to allocate family labor and how best to feed the family. The study goes beyond fish farming in rice fields to include the role of naturally occurring aquatic organisms in rice fields such as frogs, snails and wild fish.Rice-fish aquaculture, Integrated farming, Pest control, Small scale aquaculture, Socioeconomic aspects, Philippines,
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