982 resultados para Missions -- Africa, East.


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Continuous research on the freshwater fisheries industry in East Africa, in common with most other African countries, did not commence until the end of the Second World War in 1945. Before the war some work on the fishes and hydrobiology of the lakes of East Africa had been undertaken by a series of scientific expeditions, which were sent out from Europe, between the years 1896 and 1939. These expeditions usually lasted for only a few months, and the collected data were published by young graduates and undergraduates, including such people as Mr. L. C. Beadle, (lately Professor Beadle of Makerere), Mr. V. E. Fuchs (now Sir Vivian Fuchs) and Mr. E. B. Worthington of Gonville and Caius College,Cambridge. Later. Dr. Worthington became Scientific Secretary to the Scientific Council for Africa, Scientific Secretary to the East African High Commission, and played a very large part in the furtherance of fisheries research and management in East Africa.

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In June, 1961, discussions were held in London to consider the future of the East Africa High Commission Services. It was agreed that the functions of the East Africa High Commission, with the exception of Defence, should be transfered to the East African Common Services Organization, which was subsequently established on 9th December, 1961, on the achievement of independence by Tanganyika. The Common Services Organization is controlled by an Authority, consisting of the principal elected Minister in each of the East African territories, which is responsible for the overall policy and direction of the Organization. The Authority is assisted by four Ministerial Committees, of which one is responsible for the Social and Research Services of the Organization

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This report covers the period 1st July, 1955, to 30th June, 1956. As printing has been delayed for various reasons, reference should be made to certain important proposals put forward since the 30th June. Just after the close of the year a meeting of the Lake Victoria Fisheries Board was held at Entebbe on 26th July. At this meeting disagreement arose between the representatives of the three East African Governments on the subject of whether or not existing restrictions on fishing in Lake Victoria should be retained. This organization holds strongly to the view that the existing restrictions on fishing should be retained, Kenya holds similar views, but Uganda and Tanganyika were in favour of a proposal to lift these restrictions. This question was discussed a month earlier by the Director with the Colonial Office Fisheries Advisory Committee and they also advised the Lake Victoria Fisheries Board against lifting the restrictions.

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A brief review of work carried out since the laboratory was established ten years ago will put present studies into perspective and show to what extent the aims of this organisation are being fulfilled. These aims can be simply defined under two heads: the maintenance of a watch on the commercial fisheries and original research designed to provide the necessary if these fisheries are to be exploited rationally and managed efficiently. While reference to past results, which cover a wide range of subjects, can best be made in the appropriate sections of this report, a short general statement on the Lake Victoria Fisheries may be useful. From the earliest records contained in Michael Graham's Report it was clear that even before 1929 considerable inroads had been made the stocks of fish in Lake Victoria. Some control measures were subsequently introduced which must have had a moderating effect, but so the Game Department reports continued to express concern regarding the state of the fisheries. During the last war some reduction in fishing effort occurred due to ,a shortage of nets, this afforded some respite to the fisheries, but after this period the fishing effort again increased steadily. At the present time the fishing effort is higher than it has ever been.

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This Report covers the period 1st January, 1954, to 30th June, 1955. Scientific work of the organization carried out during the reporting period included the following: Hydrology, Mollusca, Arthropoda , Tilapia, Haplochromis , The Fishes of Uganda , species of fish occurring in Lake Victoria, Analysis of commercial catches, Experimental fishing, The Relative fecundity of Tilapia species, The breeding behaviour of Tilapia, The rings on Tilapia Scales, The Growth of very young fish, The reproductive cycle of non-cichild fishes, The food of fish, some notes on the food of crocodiles, Varanus Lizards and Otters and List of Publications

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The annual report presents progress on research activities carried by the organization during the reporting period. The general policy was to integrate the work of every individual on the staff so that all consider themselves members of a scientific team, and so that new problems as they arise could be investigated from more than one aspect. Already some of important findings had arisen as a result of joint studies made by two or more members of the staff working together. As far as possible the work being undertaken was designed to cover the sequence of events which lead from the chemical and physical condition of the water to the ultimate growth of the various populations of fish.

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The examination of a considerable amount of data has led to the conclusion that Lake Victoria should be considered as many lakes within a lake. This is not a vague and seemingly obvious remark based on the superficial observation that it is a very large lake containing numerous islands and with a highly indented coastline, and therefore providing variable local conditions. Such local conditions would exist in any lake whose basin departed from a simple geometric form. But evidence has now been collected to show that really significant differences occur between different regions within the lake. These differences are apparent from a variety of data, including the nature of the bottom deposits, the chemical and hydrological condition of the water, the amount and kind of plankton and the distribution and abundance of the fauna. Our findings are as yet somewhat sketchy, and it will be a long time before it will be possible to draw an adequate picture of the various regions of the lake; it is however, of great value to have reached a position enabling us to form this general concept. The most striking and definite evidence is derived, as might be expected, from hydrological data. Details of this work are contained in the hydrological section of this report. Any data recorded below should be considered as applying only to the particular areas mentioned. In other words it would, to draw an obvious example be wrong to suppose that because fish grow at a particular rate in one part of the lake they will grow at the same rate or to the same size in other regions of the lake.

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Several important advances have been made in our knowledge both regarding the factors which determine fertility in tropical lakes and the fish that live in them. As a result of our investigations a new theory has been put forward regarding the part played by animals in the bionomics of a lake; this theory, stated somewhat baldly, is that within certain limits the greater the number of animals in a shallow tropical lake, the greater becomes its potential fertility, and therefore the greater the number of animals it can support. The theory arises as a logical conclusion, once we accept the fact that the rate of production in such a lake is determined by the rate at which organic matter is decomposed. Bottom deposits which consist mainly of vegetable matter decompose slowly, whereas deposits which contain a high proportion of matter of animal origin decompose more rapidly. Thus the more animals in a lake, particularly animals which feed on plant material, the faster the biological cycle can proceed and the greater the density of animals it can support. This new concept will have a very profound influence on our ideas concerning the consequences of overfishing tropical waters. It also shows that efforts must be made to encourage and protect all herbivorous and detritus feeding animals, whether they be copepods, fish, or hippopotami, and whether they are of immediate economic importance or not.

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Although the reservoir area in south-east Asia is considerable, the fish production is low in the majority of reservoirs. Although high fish production has been recorded in a number of reservoirs in Sri Lanka and Indonesia, high fish production in reservoirs has with few exceptions resulted from the introduction of typical lake species from Africa. Addition of further lake fish species especially into deeper reservoirs will probably increase present fish yields. Diversification of the lake fish fauna can be achieved by introduction of species indigenous to the region like Etroplus suratensis. In this introduction of fish species, three points may be noted with specific reference to Tilapia spp.: (a) Lakes without indigenous cyprinids show marked fluctuation in fish catch with the introduction of Tilapia, and this could be stabilised by the introduction of predators and more diverse species. (b) Lakes with a moderate diversity of fish fauna show a high stabilised production with the introduction of Tilapia, presumably because of the effect of predator pressure on excessive Tilapia breeding. (c) Lowland lakes with a rich diversity of indigenous fish species colonising lakes may not require the introduction of Tilapia. Introduction of invertebrates into reservoirs in south east-Asia has not been done deliberately so far. However, the experience in other parts of the world, notably the Soviet Union, indicates that such introductions are likely to prove beneficial and to increase fish production. The potential for a considerable increase in fish production from reservoirs exists in south-east Asia. Proper management is likely to cost less than what is required for fish culture. Rural areas are likely to benefit most from increased fish production in reservoirs, and this might be a way to provide cheap protein where it is most urgently needed.

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The regional distribution of an ancient Y-chromosome haplogroup C-M130 (Hg C) in Asia provides an ideal tool of dissecting prehistoric migration events. We identified 465 Hg C individuals out of 4284 males from 140 East and Southeast Asian populations. We genotyped these Hg C individuals using 12 Y-chromosome biallelic markers and 8 commonly used Y-short tandem repeats (Y-STRs), and performed phylogeographic analysis in combination with the published data. The results show that most of the Hg C subhaplogroups have distinct geographical distribution and have undergone long-time isolation, although Hg C individuals are distributed widely across Eurasia. Furthermore, a general south-to-north and east-to-west cline of Y-STR diversity is observed with the highest diversity in Southeast Asia. The phylogeographic distribution pattern of Hg C supports a single coastal 'Out-of-Africa' route by way of the Indian subcontinent, which eventually led to the early settlement of modern humans in mainland Southeast Asia. The northward expansion of Hg C in East Asia started similar to 40 thousand of years ago (KYA) along the coastline of mainland China and reached Siberia similar to 15 KYA and finally made its way to the Americas. Journal of Human Genetics (2010) 55, 428-435; doi:10.1038/jhg.2010.40; published online 7 May 2010

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The beginning of the 20th century saw the discovery of Africa's vast natural resources. Not only did explorers "discover" lakes, rivers, forests and mountains but scientists and naturalists also "discovered what at that time were called new species of plants, fish and other animals. Thus scientific names were tagged to various species using the famed binomial nomenclature and immortalising the names of some of the people who first described those species. Africa of course abounds with thousands of different floral and faunal varieties and the early colonial scientists found the African environment lucrative fron the point of discovery of new species. This paper therefore attempts to descrihe the role science could only in the development and exploitation of one of Africa's renewable resources namely fisheries. This paper has attempted to expose the value of fish in human nutrition, provision of employment and uplifting of social and economic standards. The fishery resources of Africa are extensive and in the main not fully exploited. These resources like other natural resources are exhaustible although renewable. Efforts to exploit these resources must be encouraged but scientific planning and management of the resource is called for.

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The annual report present activities carried out by the different organizations that make up the East African Agricultural & Fisheries Research Council which covers reports from the following Organisations: I. Report of the East African Agriculture and Forestry Research Organization 2. Report of the East African Fishery Research Organization 3. Report of the East African Marine Fisheries Research Organization 4. Report of the East African Trypanosomiasis Research Organization 5. Report of the East African Veterinary Research Organization The activities reported are for the period 1958

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The annual report present activities carried out by the different organizations that make up the East African Agricultural & Fisheries Research Council which included: 1. Report of the East African Agriculture & Forestry Research Organization 2. Report of the East African Veterinary Research Organization 3. Report of the East African Fishery Research Organization 4. Report of the East African Marine Fisheries Research Organization The activities reported are for the period 1954-55.

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The annual report present activities carried out by the different organizations that make up the East African Agricultural & Fisheries Research Council which included: 1. Report of the East African Agriculture & Forestry Research Organization 2. Report of the East African Veterinary Research Organization 3. Report of the East African Fishery Research Organization 4. Report of the East African Marine Fisheries Research Organization and 5. Report of the East African Trypanosomiasis Research Organisation. The activities reported are for the period 1955-56.

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The annual report present activities carried out by the different organizations that make up the East African Agricultural & Fisheries Research Council which covers reports from the following Organisations: I. Report of the East African Agriculture and Forestry Research Organization 2. Report of the East African Fishery Research Organization 3. Report of the East African Marine Fisheries Research Organization 4. Report of the East African Trypanosomiasis Research Organization and 5. Report of the East African Veterinary Research Organization The activities reported are for the period 1956-57