973 resultados para Cage fish farm


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The length-weight relationship (LWR) parameters of 23 small pelagic fish species (belonging to 13 families) from the south-southeast Brazilian Exclusive Economic Zone in 1996 and 1997 are presented. The b values varied between 2.72 and 3.53. The samples for this study were collected during hydroacoustic surveys covering an area of 700 000 square km.

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This article is based on the study, Strategies and Options for Increasing and Sustaining Benefits from Fisheries and Aquaculture Production to Benefit Poor Households in Asia carried out under ADB-RETA 5945, and implemented by the WorldFish Center in partnership with nine participating Asian countries.

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Fish production on Malawian smallholdings is generally limited by the quantity and quality of inputs to the pond (Brummett and Noble 1995). The timing of labor availability and other farm activities limit the amount farmers put into their ponds resulting in lower growth rates and yields. There is potential for improving production and yields through modifications of production schedules to accommodate other farming activities. Limited material and labor inputs among farming system enterprises can be better allocated by considering seasonal availability of inputs and adapting the pond and fish farming technology to the farming system. This case from Malawi demonstrates that aquaculture technology that neglects the annual cycle of events and constraints on the farm will not be easily integrated into the farming system. Focusing on technology that maximizes fish production rather than facilitation of adoption and integration has been a feature of the majority of African smallholder agriculture/aquaculture projects. Farming Systems Research (FSR) must identify niches and opportunities for system improvement for it to be worth supporting as a development intervention.

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The article highlights the aquaculture of marble or sand goby (Oxyeleotris marmoratus) in Malaysia. Topics discussed are: breeding, hatchery and nursery techiques, nutrition, growout techniques, and diseases.

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A brief review of the status of the world fisheries is presented with emphasis on the differences between catches (= landings + bycatch), biological production of fish, and predation (= production - catches). The ECOPATH II approach implemented as a new, Windows-based software is then shown to allow construction of a stratified world model accoutinng for global catches, production of and predation on fishes, and thus improved estimates of global potentials. A newly initiated, cooperative project is described through which the foundation for such a global model could be constructed, based on a stratified database with more than 100 trophic models. Collaborators are invited to join in this, and will be assisted in constructing models covering their areas of interest.

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A simple approach is introduced to estimate the natural mortality rate (M) of fish stocks. The approach is based on the age at maximum cohort biomass, or critical length (L*) concept. The ratio of the critical length to the asymptotic length ( = L*/L8) is relatively constant in 141 fish stocks at 0.62 (CV = 21.4 per cent) and the relationship M = 3K(1- )/ is derived and could be used to estimate M, where K is the growth coefficient of the von Bertalanffy growth function. Average values of are given for the various Families of fish in order to estimate M based on closely related species.

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Ways of evaluating the effects of environmental degradation from coral mining to reef fish communties in Maldives are presented.

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Introductions of exotic finfish between 1948 and 1953 are reported in this paper, with a brief reference to earlier and later introductions. Exotic fish were introduced principally to develop the potential for aquaculture in fresh and brackish waters in order to increase the availability of fish for rural communities through the biological control of aquatic vegetation. The algal feeding tilapia (Sarotherodon mossambicus) has created a new food industry in inland and brackishwaters. It has supplemented marine fishery production in a community where animal protein intake consists mainly of fish. It is also being cultured in flooded rice fields and used in the control of malaria. This excellent table fish has not had any adverse environmental impact.

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A study was conducted in 54 wetlands of 13 districts of Assam, India to evaluate the causes of fish depletion. Twenty-two variables were considered for the study. Seven factors were extracted through factor analysis (Principal Component Analysis) based on Eigen Value Criteria of more than one. These seven factors together accounted for 69.3% of the total variance. Based on the characteristics of the variables, all the factors were given descriptive names. These variables can be used to measure the extent of management deficiency of the causes of fish depletion in the wetlands. The factors are management deficiency, organic load interference, catchment condition, extrinsic influence, fishermen’s ignorance, external environment and aquaculture program. Management deficiency accounted for a substantial portion of the total variance.

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The Sub-Saharan region of Africa accounted for only 5.5% of the world's demand for fish from 1989 to 1991, inspite of comprising 9% of the global population. This study was carried out to determine the future demand for fish in the Sub-Saharan region. Fish accounts for approximately 10% of animal protein consumed. It is prominent in the diet of the poor since cured and smoked fish is a cheaper source of protein than meat or eggs. The average per capita consumption in 1992 was about 8 kg compared to 30 kg globally. Fish is prominent in the diets of people near coastal areas and large inland water bodies and a total of 40% of fish consumed is freshwater fish. Consumption is rising in the coastal areas but falling inland, probably due to drought and overexploitation resulting in an inadequate supply. Aquaculture has not been widely adopted and does not contribute substantially to the region's supply. To determine future demand and trends, a regression analysis was carried out at the country level with FAO data on fish consumption from 1960 to 1992, using several proxies for disposable income, cost of fishery products, changes in tastes and national differences in the tradition of fish consumption. An aggregate increase in fish consumption of nearly 2.7% annually over the next few years was predicted with a strong correlation between increases in income, prices and population. Real income was a significant and positive determinant of fish consumption, even though consumption increaed more slowly than income. Given the high projected rate of population increase, the growth rate in overall fish consumption actually implies a reduction in per capita fish consumption of 0.31% annually. If technological progress can improve production and supply, aquaculture could have a significant impact on fish consumption in the region.

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Malawi is a small but densely populated country in Southern Africa. Fish is an important part of the nutrition of Malawians, providing essential protein and micronutrients. However, per capita fish consumption has halved over the ten-year period between 1988 to 1998 due to over-fishing in the lakes and doubling of the population since the 1970s, accompanied by an increase in the price of fish. This has worsened access to food insecurity, especially in rural areas, in a country where an estimated 66 per cent of the population consume less than the minimum daily calorie requirement. This paper presents an ex-post impact assessment of the development and dissemination of smallscale integrated aquaculture-agriculture technologies by The WorldFish Center and its national and international partners over more than 15 years in Malawi. The impact study measures the effects of these outputs on the degree of integrated aquaculture-agriculture (IAA) technology adoption and diffusion, the effects on farm income and health of household members, and the welfare effects of increased fish supply on the Malawian economy.

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Environmental changes due to 2 decades of drought have modified the ecosystem of the Basse Casamance, Senegal thus forcing farmers to change their practices. They have built fish ponds and diversified into crops such as peanut, millet, sorghum, cassava and vegetables. The ponds have 2 purposes - to protect ricefields against inflow of brackishwater and to raise fish. The fish complements rice, which is the main diet, adding animal protein and serving as a source of income. Although this integrated farming system is little developed at present, it has good potential to rationalize use of the resources available to farmers and to promote interactions between farm enterprises.

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Many interconnected problems involved for the conservation of freshwater fish genetic resources of India are enumerated. Some possible solutions to the problems are also discussed.

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Details are given of a framework for developing breeding programmes using experience from the Genetic Improvement of Farmed Tilapias project which focussed on Nile tilapias (Oreochromis niloticus ). The following aspects are outlined: Analysis of targeted production and marketing systems; Breeding goals; Systematic documentation and evaluation of available genetic resources and choice and genetic base; Number of strains; Breeding strategy; Selection criteria and evaluation; Production and dissemination of improved strains; and, social, economic and environmental impacts.