962 resultados para Acacia senegal
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Accurate and precise estimates of age and growth rates are essential parameters in understanding the population dynamics of fishes. Some of the more sophisticated stock assessment models, such as virtual population analysis, require age and growth information to partition catch data by age. Stock assessment efforts by regulatory agencies are usually directed at specific fisheries which are being heavily exploited and are suspected of being overfished. Interest in stock assessment of some of the oceanic pelagic fishes (tunas, billfishes, and sharks) has developed only over the last decade, during which exploitation has increased steadily in response to increases in worldwide demand for these resources. Traditionally, estimating the age of fishes has been done by enumerating growth bands on skeletal hardparts, through length frequency analysis, tag and recapture studies, and raising fish in enclosures. However, problems related to determining the age of some of the oceanic pelagic fishes are unique compared with other species. For example, sampling is difficult for these large, highly mobile fishes because of their size, extensive distributions throughout the world's oceans, and for some, such as the marlins, infrequent catches. In addition, movements of oceanic pelagic fishes often transect temperate as well as tropical oceans, making interpretation of growth bands on skeletal hardparts more difficult than with more sedentary temperate species. Many oceanic pelagics are also long-lived, attaining ages in excess of 30 yr, and more often than not, their life cycles do not lend themselves easily to artificial propagation and culture. These factors contribute to the difficulty of determining ages and are generally characteristic of this group-the tunas, billfishes, and sharks. Accordingly, the rapidly growing international concern in managing oceanic pelagic fishes, as well as unique difficulties in ageing these species, prompted us to hold this workshop. Our two major objectives for this workshop are to: I) Encourage the interchange of ideas on this subject, and 2) establish the "state of the art." A total of 65 scientists from 10 states in the continental United States and Hawaii, three provinces in Canada, France, Republic of Senegal, Spain, Mexico, Ivory Coast, and New South Wales (Australia) attended the workshop held at the Southeast Fisheries Center, Miami, Fla., 15-18 February 1982. Our first objective, encouraging the interchange of ideas, is well illustrated in the summaries of the Round Table Discussions and in the Glossary, which defines terms used in this volume. The majority of the workshop participants agreed that the lack of validation of age estimates and the means to accomplish the same are serious problems preventing advancements in assessing the age and growth of fishes, particularly oceanic pelagics. The alternatives relating to the validation problem were exhaustively reviewed during the Round Table Discussions and are a major highlight of this workshop. How well we accomplished our second objective, to establish the "state of the art" on age determination of oceanic pelagic fishes, will probably best be judged on the basis of these proceedings and whether future research efforts are directed at the problem areas we have identified. In order to produce high-quality papers, workshop participants served as referees for the manuscripts published in this volume. Several papers given orally at the workshop, and included in these proceedings, were summarized from full-length manuscripts, which have been submitted to or published in other scientific outlets-these papers are designated as SUMMARY PAPERS. In addition, the SUMMARY PAPER designation was also assigned to workshop papers that represented very preliminary or initial stages of research, cursory progress reports, papers that were data shy, or provide only brief reviews on general topics. Bilingual abstracts were included for all papers that required translation. We gratefully acknowledge the support of everyone involved in this workshop. Funding was provided by the Southeast Fisheries Center, and Jack C. Javech did the scientific illustrations appearing on the cover, between major sections, and in the Glossary. (PDF file contains 228 pages.)
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Mediterranean fish species and fish species from other southern countries are retailed increasingly on the German market. The fish is stored in ice eviscerated or as whole fish and imported by truck or by airplane. In the present investigation, the freshness, the sensory quality and the microbiological status was determined of gilthead sea breams (Sparus aurata) from farms in Italy and France and from sea breams (Sparus ehrenbergi) of wild captures from Senegal. It is shown, that farmed gilthead sea breams were of high sensory quality and in good microbiological conditions.
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An examination is made of investment prospects in the Nigerian marine fisheries, considering the following sectors: inshore demersal fishery; inshore pelagic fishery; and the offshore pelagic fishery. The marine fisheries resources of countries with which Nigeria has bilateral fishing rights agreements are discussed, considering Equatorial Guinea, Guinea Conakry, Guinea Bissau, Senegal and Mauritania. Fishing gear and methods for the marine fishery sectors are outlined. Market potentials for fish products and profitability are also examined
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A Literatura e a História sempre foram determinantes na evolução e afirmação de todos os povos que sofreram dominação estrangeira; o que, tantas vezes, levou os povos subjugados à perda de todas ou de uma boa parte de suas características específicas. Uma situação que ocasionou o questionamento das histórias destes povos - elaboradas pelos dominadores da cultura hegemônica à época e que, no nosso trabalho, são identificados como colonizadores. Este trabalho se propõe a visitar e salientar, através de duas obras bem características - a brasileira, Viva o Povo Brasileiro, de João Ubaldo Ribeiro e a senegalesa Sundjata ou a Epopéia Mandinga, de Djibril Tamsir Niane - não só o impacto das ocupações no cotidiano desses povos, mas também discutir e contribuir para a destruição da visão estereotipada desses povos espalhada pelos colonizadores antes de projetar a re-construção das identidades nacional e cultural corrompidas pela dependência cultural, uma das conseqüências da colonização. Tal será levado a cabo através de uma atuação de primeiro e segundo planos do Herói-Mito que, ultrapassando o maravilhoso e o fantástico com que se identifica geralmente sua personagem, sublinha com insistência a evolução de uma entidade totalizadora como o povo-nação: o passado, o presente e o futuro. O Senegal e o Brasil, a partir de uma exploração detalhada de suas culturas, têm plena consciência dos laços mais do que estreitos que os definem como meio-irmãos, frutos de um pai...polígamo
Resumo:
The Petersen method was used to make growth assessments from experimental data collected during 1966-67 and 1969-70. The parameters K and L ∞ were calculated from the Von Bertalanffy growth curve. There was very little difference between the two years although growth in 1969 appeared slightly greater. A comparison of our results in Côte d'Ivoire with those from Senegal and Gulf of Mexico showed that the greatest growth occured on the west African coast and especially off the Côte d'Ivoire.
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This short note gives the results of the measurements of cephalothoracic length-total weight of Penaeus duorarum in Côte d'Ivoire and compares those data to the ones collected in Senegal (Bondy 1968) and in the Gulf of Mexico (Kutkuhn 1965).
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Hydroclimatic conditions in the Gulf of Guinea between Senegal and Nigeria are briefly described emphasizing the seasonal variations of transparency. Analysis of the Abidjan based shrimp fleet allowed to the description of the seasonal variations of activity rhythms for Côte d'Ivoire, Ghana, and Nigeria. These rhythms are different between seasons, between fishing grounds, and sometimes even between depths on a given ground. These variations follow the turbidity ones. Diurnal activity is observed in very turbid waters, nocturnal and transition activity in clearer ones. The authors assume that the basic behaviour is a nocturnal one, but that the shrimp-trawlers catches reflect some apparently different ones resulting from diel variations in the stock availability. To explain the apparently diurnal behaviour observed most of the year over the whole Gulf of Guinea it is suggested that these generally benthic shrimps become nectonic at night when turbidity is very high. The results obtained in Ivory Coast, Ghana and Nigeria are compared to those from Senegal where hydroclimatic conditions are different. The similarities are emphasized. The differences in observed behaviour are supposedly caused by the cold season water temps which are sufficiently low to disturb the nor mal activity rhythm.
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Different catches per unit of effort available for industrial and artisanal sardinella fisheries of Senegal have been analysed and compared in order to determine whether they are acceptable indices of abundance. Among the four units of fishing effort studied (total number of sets, number of trips, time spent on fishing ground, searching time), the first and the second seem inadequate in the studied fleets. The two other units, particularly the searching time, allow the calculation of catches per unit of effort which best reflect variations in abundance, although they are not completely free of usual deficiencies.
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A brief account of the evolution and structure of the marine fisheries of Senegal, West Africa, is presented, with emphasis on the small-scale subsector and on the major recommendations of an international symposium/workshop on this topic, held on February 1993 in Dakar.
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A pesquisa busca analisar a operacionalização das diretrizes pedagógicas não formais oferecidas por uma Organização do Terceiro Setor, de base internacional, com comitês locais em vários municípios do Brasil. A investigação pretende, também, abordar a contribuição das programações ofertadas para o desenvolvimento de uma nova relação com o saber segundo Bernard Charlot, de acordo com avaliação dos seus membros, no sentido de interculturalidade. A escolha da organização, objeto de estudo, se justifica por ter surgido após a Segunda Guerra Mundial, em 1948, fundada por estudantes de sete países europeus (Noruega, Dinamarca, França, Suécia, Finlândia, Bélgica e Países Baixos), com o propósito de contribuir para a integração entre diferentes culturas, promovendo o entendimento e a cooperação entre seus países membros, através do intercâmbio de técnicas administrativas e de recursos humanos (AIESEC, 2014). Trata-se de um estudo de caso no qual o referencial teórico destaca os autores Maria da Glória Gohn, Jaime Trilla, José Carlos Libâneo e Simone Park por caracterizarem a educação não formal. Os conceitos relacionados ao Terceiro Setor são trabalhados à luz das concepções dos autores Leilah Landin, Sérgio Haddad e Carlos Montaño. Para o conceito de competências são usadas, principalmente, as abordagens de Acácia Kuenzer e Neise Deluiz e, finalmente, Vera Candau e Maria Aneas, para a abordagem da interculturalidade. A metodologia da pesquisa com abordagem qualitativa se utiliza de métodos diferenciados como: observação não participante, entrevista semipadronizada com quatro intercambistas, pesquisa documental e análise de documentos na internet. Os dados revelam que as práticas pedagógicas de Educação Não Formal apresentam uma dicotomia entre seus valores de paz e os seus fazeres convergentes com a lógica do mercado globalizado. A pesquisa aponta que as ações educativas deveriam ultrapassar a concepção de multiculturalismo, para a de interculturalismo, instaurando o diálogo com as diferenças.
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This brochure summarizes a series of case studies done in nine countries—Brazil, India, Indonesia, Mexico, Senegal, South Africa, Spain,Tanzania and Thailand—on the role of communities in the planning and implementation of marine protected areas (MPAs). The studies demonstrate that communities can be powerful allies in efforts for conservation and management of coastal and marine resources. They also underline the need for systematic attention, capacity building, funding and other resources for effective implementation of Programme Element 2 on governance, participation, equity, and benefit sharing of the Programme of Work on Protected Areas (PoWPA) of the Convention on Biological Diversity (CBD).
Resumo:
紫茎泽兰(Eupatorium adenophorum Spreng.)入侵我国已有70余年的时间,目前已经对我国西南地区造成了严重危害,却缺少有效的防治方法加以控制。本研究着眼于紫茎泽兰治理效果,在两片大面积综合防治样地的基础上,针对综合防治后样地紫茎泽兰再生长情况展开调查研究,并在野外观测的基础上设计两项置于样地附近的盆栽实验,研究紫茎泽兰在不同环境条件下的存活情况,以及与不同物种混播的种间竞争情况。 对综合治理1年后的样地中4个紫茎泽兰种群调查、分析结果表明,在不同的生境,采取不同的方法治理紫茎泽兰会导致紫茎泽兰采取不同的生长和繁殖对策进行再生长。紫茎泽兰生长速度为:水分充足的环境大于水分不充足的环境,萌生植株大于实生植株。种植替代物种绞股蓝(Gynostmma pentaphyllum)能够抑制紫茎泽兰的高生长,但在绞股蓝的压迫下紫茎泽兰长成L型,反而增加了冠幅、分蘖数目和单位株高的分枝数。在繁殖方式方面:采用拔除方法治理的区域紫茎泽兰以克隆繁殖为主,而采用喷洒化学除草剂治理的区域则以有性繁殖为主。 固定样方调查显示,紫茎泽兰再生长的1年当中,群落随季节变化而变。群落的盖度、密度和物种丰富度均随着旱季的深入而达到最低,第二年雨季到来后上升,紫茎泽兰在群落中处于绝对优势,尤其是在旱季优势更为明显。一年生紫茎泽兰在旱季部分植株死亡(死亡率为53.38±1.55%),少部分(5.66±0.45%)开花,产生种子的密度约为50 000ind∙m-2。与本地优势灌木物种车桑子(Dodonaea viscosa)、台湾相思(Acacia confuse)和马桑(Coriaria nepalensis)相比,紫茎泽兰具有更快的生长速度,更大的高度、密度和盖度。 紫茎泽兰种子的萌发需要充足的水分和遮荫条件。在盆栽实验当中,浇水或遮荫条件下足量紫茎泽兰的种子能够萌发更多的幼苗,而且幼苗的死亡率也比无浇水或无遮荫的处理低。在遮荫或去除其它物种竞争的条件下,紫茎泽兰幼苗生长速度更快。只要水分充足紫茎泽兰幼苗不会因拥挤而死亡,但是个体平均生物量会因拥挤而减小。 紫茎泽兰幼苗与本地3种草本植物比较结果,在未遮荫条件下,紫茎泽兰幼苗数量极少,且个体也非常小,而相同条件下荩草(Arthraxon hispidus)和含羞草决明(Cassia mimosoides)生长良好;在遮荫条件下荩草、含羞草决明和戟叶酸模(Rumex haxtatus )与紫茎泽兰相比则几乎没有优势。 成株紫茎泽兰生命力强,难以控制,幼苗时期是采用替代控制方法治理紫茎泽兰的最佳时期。在替代控制物种选择方面,可以在根除后播种本地灌木和草本植物,因为草本植物在早期可以抑制紫茎泽兰幼苗的萌发和生长,而同时播种的灌木种类则可以在植被恢复的后期起到控制紫茎泽兰再生长的重要作用。
Resumo:
Nile perch, Lates niloticus Linnaeus, 1758, is a predatory fish of high commercial and recreational value. It can grow to a length of 2 m and a weight of 200 kg. In Uganda, Nile perch was originally found only in Lake Albert and the River Nile below Murchison Falls. The species is, however, widely distributed in Africa, occurring in the Nile system below Murchison Falls, the Congo, Niger, Volta, Senegal and in Lakes Chad and Turkana (Greenwood 1966).
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Vegetation cover plays an important role in the process of evaporation and infiltration. To explore the relationships between precipitation, soil water and groundwater in Taihang mountainous region, China, precipitation, soil water and water table were observed from 2004 to 2006, and precipitation, soil water and groundwater were sampled in 2004 and 2005 for oxygen-18 and deuterium analysis at Chongling catchment. The soil water was sampled at three sites covered by grass (Carex humilis and Carex lanceolata), acacia and arborvitae respectively. Precipitation is mainly concentrated in rainy seasons and has no significant spatial variance in study area. The stable isotopic compositions are enriched in precipitation and soil water due to the evaporation. The analysis of soil water potential and isotopic profiles shows that evaporation of soil water under arborvitae cover is weaker than under grass and acacia, while soil water evaporation under grass and acacia showed no significant difference. Both delta O-18 profiles and soil water potential dynamics reveal that the soil under acacia allows the most rapid infiltration rate, which may be related to preferential flow. In the process of infiltration after a rainstorm, antecedent water still takes up over 30% of water in the topsoil. The soil water between depths of 0-115 cm under grass has a residence time of about 20 days in the rainy season. Groundwater recharge from precipitation mainly occurs in the rainy season, especially when rainstorms or successive heavy rain events happen.
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To develop genetic and physical maps for shrimp, accurate information on the actual number of chromosomes and a large number of genetic markers is needed. Previous reports have shown two different chromosome numbers for the Pacific whiteleg shrimp, Penaeus vannamei, the most important penaeid shrimp species cultured in the Western hemisphere. Preliminary results obtained by direct sequencing of clones from a Sau3A-digested genomic library of P. vannamei ovary identified a large number of (TAACC/GGTTA)-containing SSRs. The objectives of this study were to (1) examine the frequency of (TAACC)(n) repeats in 662 P. vannamei genomic clones that were directly sequenced, and perform homology searches of these clones, (2) confirm the number of chromosomes in testis of P. vannamei, and (3) localize the TAACC repeats in P. vannamei chromosome spreads using fluorescence in situ hybridization (FISH). Results for objective I showed that 395 out of the 662 clones sequenced contained single or multiple SSRs with three or more repeat motifs, 199 of which contained variable tandem repeats of the pentanucleotide (TAACC/GGTTA),, with 3 to 14 copies per sequence. The frequency of (TAACC)n repeats in P. vannamei is 4.68 kb for SSRs with five or more repeat motifs. Sequence comparisons using the BLASTN nonredundant and expressed sequence tag (EST) databases indicated that most of the TAACC-containing clones were similar to either the core pentanucleotide repeat in PVPENTREP locus (GenBank accession no. X82619) or portions of 28S rRNA. Transposable elements (transposase for Tn1000 and reverse transcriptase family members), hypothetical or unnamed protein products, and genes of known function such as 18S and 28S rRNAs, heat shock protein 70, and thrombospondin were identified in non-TAACC-containing clones. For objective 2, the meiotic chromosome number of P. vannamei was confirmed as N = 44. For objective 3, four FISH probes (P1 to P4) containing different numbers of TAACC repeats produced positive signals on telomeres of P. vannamei chromosomes. A few chromosomes had positive signals interstitially. Probe signal strength and chromosome coverage differed in the general order of P1 > P2 > P3 > P4, which correlated with the length of TAACC repeats within the probes: 83, 66, 35, and 30 bp, respectively, suggesting that the TAACC repeats, and not the flanking sequences, produced the TAACC signals at chromosome ends and TAACC is likely the telomere sequence for P. vannamei.