A global overview of aquaculture production

Aquaculture in Africa has shown gradual growth, though progress remains slow due to differences in water availability, economic conditions, and access to fisheries across countries. Therefore, this study examines the challenges and prospects of the fish farming sector in Africa. Evaluating aquaculture performance should consider factors beyond production levels or GDP contribution, such as its role in food supply, population size, and natural resource availability. Egypt leads in aquaculture contribution to national fish supply, followed by Lesotho, which focuses on exports. Ethiopia, Guinea-Bissau, and Sudan have significant per capita fish supply gaps. Egypt also dominates in total production, with 2018 output surpassing all other African countries combined. Countries like Rwanda, Burundi, Lesotho, and Benin have shown strong production growth over the past decade, while Lesotho, South Africa, and Mauritius excel in high-value aquaculture production. The combination of reaching maximum yields in marine and inland fisheries, expanding markets, urbanization, and opportunities for private-sector growth presents immense potential for aquaculture development in Africa.

Global situation in Sub-Saharan countriesEconomic development in the Sub-Saharan countries is strongly linked to the agricultural sector, which constitutes the major part of gross national product (GNP) in most of these countries. However, agricultural productivity and production in the area are very low due to erratic rainfall and especially the low level of soil fertility (Penning de Vries & Djitèye, 199; van Keulen & Breman, 1990). Considered world-wide, it is one of the regions with the most unfavourable combination of low agricultural productivity and high population growth. The potential for economic development is limited, because of environmental, agro-technical, socio-economic and institutional constraints.Natural resource degradation is most directly linked to (Oldeman et al., 1991)practicing non-sustainable land use systems, particularly agricultural production techniques without application of mineral or organic fertilisers (24% of the crop land);over-exploitation of pasture (49% of the area);over-exploitation of woody resources (27% of the woody land).The most important single cause of degradation is the depletion of soil nutrients, including organic matter. Land degradation has serious consequences for agricultural productivity and production, and the availability of arable land. It has been estimated that the availability of arable land will decrease from the current 0.28 ha per capita to 0.17 ha in 2025 (WRI, 1990) and 0.15 ha in 2050 (FAO 1991)The situation in MaliThe economic situation in Mali is characterized by a low GNP per capita (around $270 per annum). The primary sector is the most important one, contributing 46% to GNP, mainly from arable farming and livestock activities (DNSI, 1992). More than 80 % of the work force is employed in the agricultural sector, which generates around 75% of the export revenues.Low soil fertility and degradation of natural resources are the most important constraints for agricultural development in Mali. For example, in Southern Mali, the value of the nutrients (at current fertilizer prices, based on replacement value) lost in traditional cropping systems has been estimated (van der Pol, 1992) at about half the value of the gross margin. Hence, a large part of farmers' income originates from soil depletion.The study area is the 'Cercle de Koutiala' in Southern Mali, with a total area of 9075 km 2and 286 244 inhabitants, i.e. a population density of about 31 per km 2(BCR, 1991). The Cercle de Koutiala is located at the border of the Soudano-Sahelian zone with monomodal rainfall at an average of 980 mm/year (Sivakumar et al. , 1984). Six main types of soils have been distinguished, with shallow gravelly soils, not suitable for arable farming, occupying the largest area (62%).Study objectives and methodologyThe specific objectives of the study are:definition of agricultural production techniques at different levels of sustainability;formulation and analysis of a scenario for sustainable agricultural development in the Cercle de Koutiala;exploration of the potentials and constraints for future land use in the Cercle de Koutiala, based on optimum natural resource management;analysis of the actual situation, including non-sustainable production techniques at farm household level;comparison between development options (in terms of production and land use) for situations with and without the possibilities for practicing non-sustainable production techniques;identification of policy measures to stimulate adoption of sustainable agricultural production techniques at farm household level.The research methodology is based on a systems-analysis approach, using linear programming at regional (aggregate) and farm (micro) level. Model structure and procedures are presented in Chapter 3. The different steps followed in the analysis of the results are:a scenario based on sustainable intensive agricultural production techniques is analysed with a regional model in Chapter 4 to explore the agricultural development perspective for the Cercle de Koutiala;results of the Farm Household Model, based on non-sustainable agricultural production techniques, are analysed in Chapter 5, with emphasis on the structure of production, (land use), the level of production and the degree of sustainability of the land use systems practiced by different household types;results at farm level have been aggregated to the regional level on the basis of the total number of different types of farm households in the region for comparison with the development perspectives under sustainable conditions;policy measures aiming at stimulating the adoption of sustainable technical options are defined, and their impact on farm household behaviour is analysed in Chapter 6;the influence of some policy measures on aggregate production of cereals at the regional level is analysed as well as its effect on market and price equilibrium.Sustainable production systemsThe basic question in the present study is: how to realise the transition from the current non-sustainable practices (associated with ' soil mining ' ) to sustainable intensive cropping systems? To answer that question, a sustainable agricultural development scenario has been defined, based on sustainable agricultural production techniques. For definition of those production techniques, sustainability has been operationalized as 'equilibrium of nutrient balances (including soil organic matter)' to avoid soil nutrient depletion. The resulting land use systems are characterized by strong integration of arable farming, animal husbandry and forestry. Sensitivity analyses have been carried out to analyse the effects of variation in 'level of sustainability' on the level of productivity of cropping systems. The scenario based on "absolutely (no soil nutrient depletion allowed)" sustainable intensive production techniques (SP1) results in the highest level of agricultural production and net revenue, despite higher expenditures on inputs, especially for chemical fertilizer. With increasing levels of soil nutrient depletion (application of 25, 50 and 75 % of the chemical fertilizer needed for equilibrium), productivity and net revenue decrease, the cultivated area increases (extensification), and net revenue per unit area and per capita decrease.Non-sustainable production systemsThe farm household model was applied to analyse the effects of the inclusion of non-sustainable production techniques on regional development. The results indicate large differences among farm household types in terms of agricultural productivity and farm management strategy. Farm household types were defined on the basis of access to resources and the degree of mechanisation (animal traction). When maximising net revenue and utility, the level of production and net revenue are appreciably higher for households of type A (well-endowed) than for those of types B and C (less endowed). Comparison of the results of the absolutely sustainable scenario (SP1) with those of scenario SB1 (actual situation) shows large differences in allocation of natural resources (land use), production and level of sustainability. Adoption of intensive, sustainable production techniques requires some major actions at farm household level:efficient land resource management, i.e. land use adapted to land qualities and suitability;integration of silviculture to satisfy wood requirements;intensification of livestock systems through introduction of high-quality supplementary feed. This leads to the conclusion that complementary policy measures are indispensable to stimulate adoption of sustainable and intensive technical production techniques.Policy measuresPolicy measures have been identified and their impact on farm household behaviour has been analysed using a farm household model. The policy measures considered include: price policy, market development policy, credit policy, natural resources management policy, and agricultural intensification policy. The policy measures could be classified in four main types on the basis of their effects on net revenue and sustainability level:policy measures having a strong positive effect on both net revenue and sustainability level;policy measures having a moderately positive effect on net revenue and sustainability level;policy measures having a moderately positive effect on net revenue and a negative effect on sustainability level;policy measures having a negative effect on both net revenue and sustainability level.Results indicate that several policy measures can have a strong effect on farm household behaviour. However, farm households vary strongly in their reactions to policy measures. Farm households of type A, for example, show an adoption rate of sustainable intensive production techniques of about 40% (expressed as the proportion of the area cultivated with these techniques) compared to 20% and 11% for types B and C, respectively. However, even when implementing the most effective policy measures, farm households generally combine non-sustainable and sustainable production techniques. The rate of adoption of sustainable intensive techniques strongly depends on their profitability. Hence, all policy measures that contribute to improved profitability of the alternative production techniques, by reducing their cost/benefit ratio, will stimulate increased rates of adoption at the farm household level. At the regional level, the most effective policy measures have a strong impact on development objectives through increasing the level of production and net revenue per ha and per capita. These policy measures also have a strong positive impact on the rate of adoption of sustainable and intensive production techniques at the farm household level. Some policy measures also induce changes in total production and hence in the demand/supply balance of cereals at the regional level. This may lead to price changes causing a new market equilibrium.The analyses of the effects of policy measures at farm household and regional level illustrate the potential role of such models in policy support in the macro-economic policy formulation process.From non-sustainability to strong sustainability: what are the possibilities for on-farm practices?The results from the regional model indicate that when sustainable intensive cropping systems are introduced, using high input levels, particularly of chemical fertilizers, high levels of production can be attained. However, such sustainable intensive systems cannot be adopted in the short term because of technical, socio-economic and institutional constraints. These constraints are mainly linked to availability of mineral fertilizers and profitability of their use.Therefore, what is required to realize the transition from the current non-sustainable practices to strong or absolute sustainability? Sustainable agricultural development requires at least a change in farm household behaviour by adopting sustainable and intensive production techniques.In the short and medium term, farm households can adapt by introducing improved, intensified forage production techniques (leguminous species), which will have a positive impact on soil fertility and livestock feed supply. For the long term, the results of the analysis of effects of policy measures have indicated that the rate of adoption of sustainable technologies can be increased through appropriate policy measures.Thus, a set of policy measures is necessary to stimulate introduction of sustainable agriculture practices at the farm level such as: increasing profitability of the use of mineral fertilizers, land improvement, improved land tenure regulations, decentralization of the responsibilities for implementation of development measures, coordination of development activities at regional level, stimulation of investments in rural areas, and of scientific and technical research oriented towards sustainable agricultural development.The Cercle de Koutiala is one of the regions in Mali with high agricultural potential, but agricultural production growth should not be realised on the basis of soil nutrient depletion, since that will trigger land degradation and environmental problems in the long term. Macro-economic policy measures are necessary to provide incentives to farm households to adopt sustainable and intensive production techniques. Only in that way will it be possible for the Cercle de Koutiala to maintain its important place in Mali's sustainable agricultural development process.

Food vs Biofuel

Comparison of projected water availability and demand reveals future hotspots of water stress in the Red River basin, USA

The U.S.‐China trade conflict has already considerably reshaped China's food imports, and should the conflict continue, it might have substantial impacts on global food supply dynamics as well as China's food supply sources. We address these implications by analyzing recent trends in China's food imports and associated use of land and water resources. We show that China's limited land and water availability will make it challenging to replace soybean imports from the United States with its own production, but switching to new trading partners by investment and cooperation could secure China's food supply while avoiding much negative environmental impacts on exporting countries.

Greenhouse Gases and Human Well-Being: China in a Global Perspective

During the last half century, or somewhat more, the United States has been one of the major fish producing countries of the world. Between 1930 and the late 1940s it was second only to Japan. Since that time it has declined in total production compared to other countries, was down to sixth in rank for a short while, and in 1982 it ranked fourth, exceeded by Japan, the USSR, and mainland China. This is not as bad as it sounds, however, because the United States is somewhat more particular than these other countries in the kinds of fish and shellfish it eats, and we have turned to imports to supply additional quantities of those kinds of fish that we cannot produce at home. In 1982, for example, we imported 5,644 million pounds of all kinds of fishery products, for a total supply of 12,011 million pounds. The total production in the world in 1981 was 74.8 million metric tons or about 167,552 million pounds, so the United States uses about 7 percent of total world production. If we consider the foreign catch in the United States Fishery Conservation Zone (within 3 and 200 miles of the United States coast), it comes to about 1,654,690 metric tons or about 3,707 million pounds. So the total catch by United States and foreign fishermen around our coast out to 200 miles is about 15,733 million pounds, or about 9.4 percent. Thus, the potential United States catch off our coasts and in some foreign waters is probably in the neighborhood of 16,000 million pounds or about 10 percent of total world production.

A model for persistency of egg production

An accurate assessment of food security and its challenges is essential for formulating effective measures and promoting sustainable socioeconomic development. This study develops an evaluation system for China's food security, focusing on four dimensions: food supply, food access, food production stability, and food continuity. The entropy weight extended matter element model is used for quantitative processing, which ensures that the integrity of the information can be guaranteed to a greater extent while reducing the influence of subjective factors, and then, the study evaluates the food security of different functional areas in China, and finally, it diagnoses the main obstacles to food security by using the obstacle degree model. (1) From 2000 to 2020, China's food security level fluctuated, initially declining, and then increasing. The food security level in major production and marketing areas is generally higher, while the primary marketing areas exhibit the lowest security levels. (2) The level of grain yields and the total power of machinery per unit area are the key factors affecting food security; the impact of inputs of agricultural materials (fertilizers and pesticides) on food security has decreased and is constantly stabilizing. In the main marketing area, the per capita food share is significantly lower than in the other functional areas, which has the greatest impact on food security. (3) Analysis of the obstacle factors reveals that the food supply and access security subsystems are crucial for ensuring national, production, and marketing security. From 2000 to 2020, the average obstacle degrees of food supply and food access security at the national level were 46.56% and 21.17%, respectively; for the production and marketing areas, they were 58.47% and 21.45%; and for primary marketing areas, they were 37.69% and 26.59%. In major grain-producing areas, the main obstacles lay within the food supply security and food production stability subsystems, with average obstacle degrees of 53.77% and 15.67%, respectively, from 2000 to 2020. The above results provide a scientific basis for comprehensively improving the level of food security in China, optimizing the structure of food production in each functional area, and formulating regionalized policies for stabilizing and maintaining food production and supply.

This articlefocuses on the relative levels of farm sector productivity forthe United States and nine European countries for the period1973 to 1993. At the beginning of the period, Belgium had thehighest level of productivity relative to the United States at1.689. Ireland had the lowest relative productivity at 0.759.By 1993, the range of levels of productivity had narrowed significantly,from 0.709 for Ireland to 1.392 forthe Netherlands. Further evidence of convergence can be seenin the coefficient of variation, which fell steadily from 0.261in 1973 to 0.227 in 1993. Results based on regressionanalysis show a highly significant inverse relation between therate of productivity convergence and the initial level of productivity,consistent with the ``catch-up'' hypothesis. The results generallysupport the existence of a positive interaction between capitalaccumulation and productivity growth, suggesting embodiment.

The article covers the development of the national publishing industry. The peculiarities of publishing products as a commodity are highlighted, the scheme of interrelations of participants of the publishing process is given, which can be divided into three processes, externally separated from each other: intangible production; material production; turnover of goods / services. The main reasons for the inefficient development of the publishing industry are identified, such as low competitiveness of products, outdated material and technical base, which, in turn, requires appropriate measures of state institutional support. Changes in the volume of printing production are characterized and the production of books is analyzed, where there is a reduction in print runs, displacement of Ukrainian producers, stagnation of basic printing resources, further dependence of the Ukrainian publishing industry, lagging behind in the development of modern information technologies. society to obtain complete information. In just 6 months of 2020, the book market fell in titles and circulations and lost professionals and players, and the release of books and booklets compared to the same period in 2019 amounted to 13.9% in circulation and 35.7% in titles, ie a drop in titles in Ukrainian 62.7%, in Russian 72.5%, but in circulation – almost the same 86.2% and 86.3%, respectively. The strengths of the publishing industry are highlighted and the main factors hindering the development of the industry are explored and recommendations and options for supporting the industry are given. It is concluded that for the development of the publishing industry, public institutions must actively participate in improving the quality of life in society, it is necessary to create an array of information about entities that are related to the industry, their evaluation and ranking of business performance. It is necessary to stimulate the rise of competitiveness in the publishing industry, invest money in equipment and modern technologies, training and retraining of labor resources, ensure the development of digitalization of economic processes, implement a set of measures to stimulate investment and innovation.

As the World Food and Nutrition Study (WFNS) points out, the United States must increase its support of certain high priority research areas now if the people of the world are to be free from hunger in the year 2000. With adequate support and selection of priorities, it is almost a certainty that the people can be fed. In the areas of crop and animal production, insect control, and aquatic food sources alone, the study teams appointed by the National Academy of Sciences have identified seven high priority areas, which if pursued vigorously could easily double or triple the world's food supply within the next twenty-five years. These areas are integrated pest management, nitrogen fixation by soil microorganisms, increasing photosynthetic rates, genetic manipulation, breeding resistance of plants to such stresses as drought and acidic soils, increasing livestock carrying capacity of grazing lands, controlling diseases such as sleeping sickness or East Coast Fever in livestock, and reducing the waste in fish processing. They offer major new pathways for the increase in food supplies. If research proved successful in the areas listed above, and if research findings were translated into farming practices in the developing countries, the food supply could essentially be doubled again by the year 2000 as it was in the developing countries between 1950 and 1975. This earlier doubling, the only gain of its magnitude in history, resulted primarily from increased use of fertilizers and pesticides and from traditional plant breeding. It may be instructive as an example to describe in more detail the research proposed for one of these major areas, that of plant stress. Until now most efforts to overcome the effects

In this paper, we make a comparison of industry output, inputs and productivity growth and levels between seven advanced economies (Australia, Canada, France, Germany, the Netherlands, United Kingdom and United States). Our industry-level growth accounts make use of input data on labour quantity (hours) and composition (schooling levels), and distinguish between six different types of capital assets (including three information and communication technology (ICT) assets). The comparisons of levels rely on industry-specific purchasing power parities (PPPs) for output and inputs, within a consistent input-output framework for the year 1997. Our results show that differences in productivity growth and levels can be mainly traced to market services, not to goods-producing industries. Part of the strong productivity growth in market services in Anglo-Saxon countries, such as in Australia and Canada, may be related to relatively low productivity levels compared with the United States. In contrast, services productivity levels in continental European countries were on par with the United States in 1997, but growth in Europe was much weaker since then. In terms of factor input use, the United States is very different from all other countries, mostly because of the more intensive use of ICT capital in the United States.

Most of man's food supply comes from the soil, either directly through food crops or indirectly as animal products. The total amount of food produced depends on the fertility of the soil. Many peoples of the world are undernourished because the productivity of the land available is not sufficient to supply the total amount of food needed. A low level of productivity, either absolutely or in terms of the population to be fed, means a lower standard of living. Poverty is often accompanied with malnutrition and disease. In these respects soil conservation and improvement are of great general importance for the promotion of health. A more direct relationship between soils and health is assumed in the thesis that the nutritional quality of the food supply and particularly of specific foods, apart from the total amount produced, is governed by the fertility level of the soil and is thus influenced by

I address two long-standing scientific problems in this thesis: the mechanism(s) of long-runout in large landslides; and the activity of water on the surface of Mars late in its history. Long-runout landslides form significant geologic risks. My research has aimed at understanding the factors that control the initiation and runout of large landslides wherever they occur. A second objective of this research has been to use martian landslides to gauge the activity of liquid water on Mars' surface over the past quarter of its history. To achieve these objectives, I made field observations of six moist and dry landslides in the western United States, I studied all the high-resolution Viking Orbiter images for large landslides on Mars and I collated all the available literature data on large landslides, to develop the clearest view possible of the nature of the large landslide process. I then used this information to evaluate all the previously published models of long runout, and to develop my own theory when I found that none of the existing theories provided an adequate explanation of the observations. I conclude that large landslides primarily slide and spread into place over fluidized natural basal lubricants. This concept follows upon the air-layer lubrication theory of Shreve, but does not call upon a gas lubricant, a possibility ruled out by the presence of Blackhawk-like long-runout landslides on Mars. Rather, the lubricants appear to be fine-grained materials from the substrate or from the landslide debris itself that deform plastically at the high shear stresses and strain rates present beneath large rapid landslides. Large dry landslides grade into moist debris flows as water becomes incorporated into their fine-grained component. Moist and dry landslides differ markedly in sedimentology and morphology, but not in a variety of quantitative relations. Seven landslide events on Mars appear to have involved water during runout, based on comparisons with water-bearing landslides of similar morphology and volume on Earth. These deposits occur primarily in Valles Marineris and indicate that liquid water has been sporadically available on Mars at various times over the last ~1 billion years of its history.