986 resultados para Parnaíba Basin


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The Nabugabo lakes are an important source of affordable protein food in the form of fish, income, water for domestic and commercial purposes (aquaculture farm and Hotels), handcraft materials (mats, hats, roof thatch) and fishing floats and rafts. Nabugabo lakes provide employment, income and export earnings to Uganda that flow from the act of harvesting the fish. In Uganda the fisheries sector directly employs 350,000 people and indirectly 1.2 million people. In 2005, it is estimated that about 370,000 mt fish export (97-98% Nile perch) earned Uganda US $ 143 Million up from US $ 103 million in 2004 .and up from US $ 45 million in 1996. , making it almost become the first non' traditional export commodity. The Nabugabo lakes are also import for cultural values and fish species from these lakes are important in evolutionary studies. The fishery sector is therefore very important in Uganda's socio-economic life. Despite the above values to the communities and global biodiversity roles, the amount of fish caught and the number fishing fleets operating on the Nabugabo lakes to guide management of the lake are lacking. The fishery that exists in these lakes is largely for subsistence and commercial purposes specific for Lake Nabugabo based on introduced species (Nile perch and Nile Tilapia). The fish is caught using mainly gill nets and long line hooks.

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Phytoplankton (52 species; Bacillariophyceae>Chlorophyceae>Cyanophyceae> Euglenophyceae=Dinophyceae) of Samuajan beel, a tropical floodplain lake, registered identical mean annual richness (30+4 species) in littoral and limnetic regions and depicted 33.3-77.2% and 31.4-81.1% community similarities respectively. Their abundance ranged between 137+54 n/l in littoral (Bacillariophyceae>Chlorophyceae) and 122 ± 45 n/l (Chlorophyceae>Bacillariophyceae) in limnetic communities, comprised about 46% of net plankton and indicated winter peaks. This study depicted moderate species diversity, high evenness and low dominance of phytoplankton; species diversity showed significant direct correlation with richness and evenness and an inverse relationship with dominance. Phytoplankton showed significant positive relationship with transparency and silicate and negative with water temperature, rainfall, chloride and nitrate. Multiple regression revealed that ten abiotic factors accounted for >80-98% of density variations of phytoplankton and the dominant groups. ANOVA depicted trends of significance in abundance of the biotic communities analysed.

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A comprehensive study on the fisheries aspect was done in the Sylhet basin, Bangladesh during 1994 through 1998. Maximum fishing effort was engaged in the period of April to September while the bulk catch came during the September-January, when less effort was exerted. Barbs comprised 19%, catfishes 18% and major carps 16% of the total catch. Chatla beel, a three years pile, showed the highest fish production. Nine types of nets, four types of hooks and five types of traps were found in operation in the basin. The highest daily mean catch was recorded in glzer jal (26.5 kg/day) and the lowest in the clzandi jal (2.5 kg/day). Behundi jal was the most efficient (0.89 kg/man/h) while chandi jal was the worst (0.12 kg/man/h) gear. Gill net (/ash jal) seems to be the best selective gear. Actual catch/effort always remained less than the projected catch/effort. Maximum economic point of effort lies around 7.0 mandays/km2 and the fishery is gradually moving towards over-fishing. Income of professional fishermen was comparatively high than that of non-professional subsistence groups.

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The study was conducted to investigate the communities perception and compliance to community-based fisheries management (CBFM) in Turag-Bangshi floodplains under Kaliakoir, Gazipur District. Measures such as ban on use of the harmful fishing gears, seasonal fishing closure, halt of fry fishing, halt of dewatering of beels and the impact of establishment of sanctuaries on fish production and species diversity were introduced by MACH project. Almost all members of the communities in Turag-Bangshi MACH (Management of Aquatic Ecosystem through Community Husbandry) site welcomed the introduction and complied with the implementation of all management measures which helped stopped use of harmful fishing gears, ensured survival and breeding of brood fish in the rainy season, protected and allowed fry to grow big, restored lost and degraded fisheries and organized communities for sustainable development of the fisheries. A total of 51 species of fishes were found in Makosh beel (natural depression). Among these, small indigenous species (SIS) under Cyprinidae family (Puntius sophore) was the most dominant. Many species available in the past recorded disappeared from the Makosh beel due to loss of habitat and industrial pollution that damaged spawning and nursery grounds of fish. Introduction of some selective native endangered species (Nandus nandus, Notopterus notopterus, Ompok pabda and Labeo calbasu) by MACH in the Turag-Bangshi water bodies increased diversity of species from 82 to 95. Over a period of five years during MACH intervention, the average production remained nearly 200% higher than the baseline production of 57 kg/ha to present 207 kg/ha due to maintaining sanctuaries and the closed fishing seasons. Per capita daily fish consumption of the surrounding communities also increased by 78% (from 27 to 48 g/person/day) which is much higher than the national average fish consumption in Bangladesh. The implementation of community-based MACH project management measures substantially improved fish habitat, production, consumption and socio-economic conditions of the surrounding communities. The model can be used to improve the floodplains of Bangladesh.

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A comprehensive Frame survey was carried out in lakes Kwania, Kyoga and the Kyoga basin minor lakes which include Lake Sisina in 2002 (Figure 1). The Frame survey was coordinated by the Department of Fisheries Resources (DFR) assisted by the National Fisheries Resources Research Institute (NAFIRRI) with technical support. The riparian districts through the sub-county fisheries offices and the BMUs provided the enumerators and supervisors. The frame survey captured all the important characteristics of the fisheries and facilities supporting the fisheries and thus provides a strong baseline for future reference of management interventions in the basin.

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2003年4月,于怒江二级支流镇康县境内的大叉河中采获一批墨头鱼属(Garra)鱼类标本,经鉴定为一新种,命名为怒江墨头鱼(G.nujiangensis Chen and Yang,sp.nov.).该新种主要鉴别特征:围尾柄鳞12~14:侧线鳞48~50:在小个体中有一对微小的吻须;背鳍分支鳍条8~9;侧线上鳞5~6,侧线下鳞3~4;体高小于头长;臀鳍起点处的小于眼后至吻端的距离;腹鳍前长为体长的50.0%~53.7%;肛门前长为体长的58.9%~63.9%:体宽为体长的16.7%~19.6%:体高为体长的19.2%~22.6%.本研究证实,在缺须的墨头鱼属的一些物种中,如高体墨头鱼(G.alticorpora)和怒江墨头鱼(G.nujiangensis),其幼体中往往具有一对很小的吻须.

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鱼类主要分布于青藏高原周边, 是一群适合于急流生活的 科鱼类。在独龙江流域7 个点共采 集271 号  鱼类标本(隶属 属、 属和异齿 属) , 结合各采集点数据绘制大鳍异齿 、藏 和扁头 的分布 直方图, 结果显示, 藏 ( E. labiatum) 在流速较快的独龙江下游各采集点的种群数量较上游高, 更适应急流生 境。同时研究了这3 种  鱼类的体长与体重的关系, 参数b (W = aLb) 的范围在218201 和310131 之间, 均为异 速生长; 藏 的生长类型最接近等速生长。

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We examined socio-economic variables that contribute to malnutrition in selected communities in the Lake Victoria basin during 2001. The study was carried out in nine districts and hinterland communities up to 25 km awayfrom the beach were used as the reference population. The main variables examined were: feeding habits, income and intra-household food distribution and living standards. Others included disease and health, sanitation and hygiene, childcare and mothers' age and workload, weaning practices, agricultural production and food availability, care during pregnancy and food taboos.

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Water hyacinth is a free-floating waterweed native to the Amazon River Basin in South America. In its native range, water hyacinth is not an environmental problem, although the weed is one of the most invasive alien plants in freshwater environments. Water hyacinth has the potential to become invasive through fast vegetative reproduction and rapid growth to accumulate huge biomass and extensive cover in freshwater environments. Over the last 150 years water hyacinth has invaded most countries in the tropics and sub-tropics, introduced by man, mainly for ornamental purposes. Such introductions led to the infestation of most freshwater-ways in the southern United States of America, parts of Australia, the pacific islands, and most countries in Asia and Africa. The extensive tightly packed mats of water hyacinth are often associated with devastating socio-economic and environmental impacts. Invasion by the weed has, therefore, often generated urgent costly problems associated with the weed biomass and its management. A classic example of such problems was triggered by the invasion and proliferation of water hyacinth in the Lake Victoria Basin during the 1980s (Freilink 1989, Taylor 1993, Twongo et al., 1995). The weed infestation marked the beginning of a decade of intensive and systematic campaign by the three riparian states (Kenya, Tanzania and Uganda) to bring weed proliferation under control. The discussions in this Chapter span over ten years of dealing with the challenges paused by the imperative to manage infestations of water hyacinth in the Lake Victoria Basin. The challenges included the need to understand the dynamics of water hyacinth infestation; its distribution, proliferation and impact modalities; and the development and implementation of appropriate weed control strategies and options. Most specific examples were taken from the Ugandan experience (NARO, 2002).

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Of all the great lakes, Lake Victoria has the highest population concentration on its fringes. This has resulted into serious human impacts on the ecosystem through intense agricultural activities (cultivation, livestock and over fishing), sporadic settlements, urbanization and industrial establishments. The consequences have been loss of animals and plant life, deforestation and general land degradation, pollution, loss of water quality and clean air. Aquatic life has become endangered and less guaranteeing to continued fish production. Awareness workshops and general talks have been done to a few selected communities by the lakes landing sites and in the catchment area to mitigate the deteriorating environmental conditions. Naturally the situation calls for reversal to the increasing stress of the ecosystem. As a result, every water body surveyed put forward some mitigation suggestions

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Aquatic macro-invertebrates encompass all those organisms that be seen with unaided eyes. Most macro-invertebrates are categorised as semi-aquatic in that they are aquatic in early stages, but live as terrestrial organisms as adults, while others like gastropods, bivalves, Oligochaetae, Hirudinae and ostracods are exclusively aquatic. Some of them such as mayflies lay eggs in water and subsequent stages also live in water until adulthood when they emerge to live a terrestrial life. In others, eggs are laid near the water, while some like members of Tendipedidae (midges) lay their eggs on the leaves of aquatic macrophytes and after hatching their larvae creep into water

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Genetic biodiversity is the vaflatlOn among individuals within and between units of interbreeding individuals (populations) of a species. It includes inheritable and transmittable differences that occur between individuals andlor popuhitions of a given species through reproductive interaction. There exists enormous variability among individuals andlor populations of a species for most living organisms, and most of this variation is inheritable. differences among individuals arise through mutation and via recombination of genes during meiosis. These ifferences are then transmitted to successive generations through sexual reproduction and maintained in the populations through processes such as natural selection and genetic drift. Unfortunately much of this variation is normally threatened and often in danger of extinction because most focus in conservation of natural resources is put at saving species or habitats than varieties or strains of a species

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The Victoria and Kyoga lake basins had a high fish species diversity with many fish species that were found only in these lakes. Two Tilapiines species Oreochromis esculentus and Oreochromis variabilis were the most important commercial species in these lakes and were found nowhere else on earth except in the Victoria and Kyoga lake basins (Graham 1929, Worthington 1929). Lakes Kyoga and Nabugabo also had endemic haplochromine species (Worthington 1929, Trewavas 1933, Greenwood 1965, 1966). As stocks of introduced species increased, stocks of most of the native species declined rapidly or disappeared altogether. The study was carried out on Lakes Victoria and Kyoga, River Nile, some selected satellite lakes from the two basins namely Lakes Mburo, Kachera, Wamala, Kayanja, Kayugi, Nabugabo, Victoria, Victoria nile and River Sio(Victoria lake basin). Lakes Kyoga (Iyingo), Nawampasa, Nakuwa, Gigati, Nyaguo, Agu, Kawi and Lemwa (Kyoga lake basin). Species composillon and relative abundance of fishes were estimated by detennining the overall average total number of each species encountered. A trophic consists of species using the same food category. Shannon-Weaver Index of diversity H (Pielou, 1969) and number of trophic groups, were used to estimate the Trophic diversity of various fish species in the lakes. Food analysis has been done on some fishes in some of the sampled lakes and is still going on, on remaining fishes and in some lakes. Generally fish ingested detritus, Spirulina, Melosira, filamentous algae, Planktolyngbya, Microcysists, Anabaena, Merismopedia, Spirogyra, higher plant material, rotifers, Ostracodes, Chironomid larvae and pupae, Choaborus larvae, Odonata, Povilla, Insect remains, Caridina, fish eggs and fish. Eight trophic groups were identified from thes food items ingestes. These included detritivores, algae eaters, higher plant eaters, zooplanktivores, insectivores, molluscivores, prawn eaters, paedophages and piscivores. Trophic diversity by number of trophic groups was highest in Lake Kyoga (6) followed by lakes Kayugi, Nabugabo, River Nile and Mburo (3) and the lowest number was recorded in kachera (2).

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The rapid proliferation and extensive spread of water hyacinth Eichhornia crassipes (Mart) Solms in the highland lakes of the Nile Basin within less than 15 years of introduction into the basin in the 1980s pauses potential environmental and social economic menace if the noxious weed is not controlled soon. The water weed has spread all round Lake Victoria and, in Uganda where infes tation is mos t severe, water hyacinth estimated at 1,330,000 ton smothers over 2,000 ha of the lakeshore (August,1994). Lake Kyoga which already constantly supplies River Nile with the weed is infested with over 570 ha, while over 80% of the river course in Uganda is fringed on either side with an average width of about 5m of water hyacinth. As the impact of infestation with water hyacinth on water quality and availability, transportation by water, fishing activities, fisheries ecology, hydro-power generation etc becomes clear in Uganda, serious discussion is under way on how to control and manage the noxious weed. This paper pauses some of the questions being asked regarding the possible application of mechanical and chemical means to control the water weed.Uganda has already initiated the use of biological control of water hyacinth on Lake Kyoga with a strategy to use two weevils namely Neochetinabruchi and Neochetina eichhorniae. The strategy to build capacity and infrastructure for mass multiplication and deployment of biological control of the weevils in the field developed in Uganda by the Fisheries Research Insti tu te (FIRI) and the Namulonge Agricultural and Animal production Research Insti tute (NAARI) is proposed in outline for evaluation. Plans to deploy this strategy on lake Kyoga are under way

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Increased management attention to the fisheries tn Uganda is fuelled by five major factors:socio-economic demands, human population increase,stock depletion, biodiversity loss and,environmental degradation.Fish exports from Uganda to overseas and regional markets have rapidly increased since the mid 1990s and it is estimated that total exports are worth at least US$ 200m three quarters of the value due mostly to Nile perch exports to overseas markets.Exports to regional markets are dominated by variously processed tilapia "mukene" (Rastrineobo/a argentea),Nile perch "angara"(A/estes baremose) and cat fishes.Virtually all major water bodies contribute to this trade. A combinatilm of exports and an increased human population has seen the per capita fish consumption in Uganda drop from 15kg in the early 1990s to almost 10kg by 2005.this figure is below the WHO recommended fish protein intake of 17kg. the apparent fish gap in a liberalised economic framework has stimulated interest in commercial fish farming