6 resultados para Transportation Supply-Demand Modeling.

em Aquatic Commons


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It has been predicted that the global demand for fish for human consumption will increase by more than 50% over the next 15 years. The FAO has projected that the increase in supply will originate primarily from marine fisheries, aquaculture and to a lesser extent from inland fisheries, but with a commensurate price increase. However, there are constraints to increased production in both marine and inland fisheries, such as overfishing, overexploitation limited potential increase and environmental degradation due to industrialization. The author sees aquaculture as having the greatest potential for future expansion. Aquaculture practices vary depending on culture, environment, society amd sources of fish. Inputs are generally low-cost, ecologically efficient and the majority of aquaculture ventures are small-scale and family operated. In the future, advances in technology, genetic improvement of cultured species, improvement in nutrition, disease management, reproduction control and environmental management are expected along with opportunities for complimentary activities with agriculture, industrial and wastewater linkages. The main constraints to aquaculture are from reduced access to suitable land and good quality water due to pollution and habitat degradation. Aquaculture itself carries minimal potential for aquatic pollution. State participation in fisheries production has not proven to be the best way to promote the fisheries sector. The role of governments is increasingly seen as creating an environment for economic sectors to make an optimum contribution, through support in areas such as infrastructure, research, training and extension and a legal framework. The author feels that a holistic approach integrating the natural and social sciences is called for when fisheries policy is being examined.

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This contribution is a summary of the results of the study conducted by the University of the Philippines in the Visayas team from November 1990 to June 1991. The purpose of this research is to estimate demand and output supply elasticities in gillnet and seine fishing in Guimaras Strait (Philippines) and adjacent waters.

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Nowadays, Caspian Sea is in focus of more attentions than past because of its individualistic as the biggest lake in the world and the existing of very large oil and gas resources within it. Very large scale of oil pollution caused by development of oil exploration and excavation activities not only make problem for coastal facilities but also make severe damage on environment. In the first stage of this research, the location and quality of oil resources in offshore and onshore have been determined and then affected depletion factors on oil spill such as evaporation, emulsification, dissolution, sedimentation and so on have been studied. In second stage, sea hydrodynamics model is offered and tested by determination of governing hydrodynamic equations on sea currents and on pollution transportation in sea surface and by finding out main parameters in these equations such as Coriolis, bottom friction, wind and etc. this model has been calculated by using cell vertex finite volume method in an unstructured mesh domain. According to checked model; sea currents of Caspian Sea in different seasons of the year have been determined and in final stage different scenarios of oil spill movement in Caspian sea on various conditions have been investigated by modeling of three dimensional oil spill movement on surface (affected by sea currents) and on depth (affected by buoyancy, drag and gravity forces) by applying main above mentioned depletion factors.

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It is generally recognized from the food balance sheet prepared by experts that Nigeria is a protein deficient country. Not only is the daily intake of protein low but the contribution from animal sources is extremely low. Fish has been found to be the cheapest source of protein in Nigeria hence the consumption of fish will supply the needed protein at a relatively low cost. The study, conducted in Calabar in 1981, was analysed using stepwise ordinary least square multiple regression technique as well as Pearson correlation analysis. The regression result was used to generate some demand curves for different levels of per capital income, as well as own price elasticity of demand. The results show that both own price elasticity of demand for fresh and frozen fish decreased as the level of per capital income increased while income elasticity of demand increased as per capital income increased. The calculated per capital consumption was found to be 5.18 kilograms and 4.31 kg per annum for fresh fish and frozen fish respectively. This is considered rather small since Calabar is a sea port where fish should be more readily available. The values of own price and income elasticities indicate that more fish will be consumed at every increase in income if both production and marketing are improved

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In the past, agricultural researchers tended to ignore the fisheries factor in global food and nutritional security. However, the role of fish is becoming critical as a result of changes in fisheries regimes, income distribution, demand and increasing international trade. Fish has become the fastest growing food commodity in international trade and this is raising concern for the supply of fish for poorer people. As a result, the impact of international trade regimes on fish supply and demand, and the consequences on the availability of fish for developing countries need to be studied. Policies aimed at increasing export earnings are in conflict with those aimed at increasing food security in third world countries. Fisheries policy research will need to focus on three primary areas which have an impact on the marginal and poorer communities of developing countries: increased international demand for low-value fish on the supply of poorer countries; improved aquaculture technologies and productivity on poorer and marginal farmers; and land and water allocation policy on productivity, food security and sustainability across farm, fishery and related sectors. The key to local food security is in the integration of agriculture, aquaculture and natural resources but an important focus on fisheries policy research will be to look at the linkages between societal, economic and natural systems in order to develop adequate and flexible solutions to achieve sustainable use of aquatic resources systems.

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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.