5 resultados para Multidimensional scaling

em SAPIENTIA - Universidade do Algarve - Portugal


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Tese de dout., Ciências e Tecnologia das Pescas, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2005

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Discards from five of the most important fisheries (crustacean trawling, fish trawling, demersal purse seining, pelagic purse seining and trammel netting) in southern Portugal were studied and compared. A total of 236 species of all taxa were discarded, with fish and cephalopods accounting for more than 90% of the discarded biomass, except trammel nets (81%). Although there was some overlapping of species, multivariate analysis using cluster analysis for classification and multidimensional scaling (MDS) for ordination, showed that there were significant differences between the five gears in terms of species composition and biomasses discarded, with the least similarity between crustacean trawling and all other fishing operations. The differences between fisheries were probably as a result of a combination of gear selectivity and depth fished. The results suggest that discarding practices are likely to have different, yet significant impacts on the marine ecosystem, warranting further studies on the fate of discards, the factors influencing discarding and mitigation.

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We identified and quantified the effect of season, depth, and inner and outer panel mesh size on the trammel net catch species composition and catch rates in four southern European areas (Northeast Atlantic: Basque Country, Spain; Algarve, Portugal; Gulf of Cadiz, Spain; Mediterranean: Cyclades, Greece), all of which are characterised by important trammel net fisheries. In each area, we conducted, in 1999-2000, seasonal, experimental fishing trials at various depths with trammel nets of six different inner/outer panel mesh combinations (i.e., two large outer panel meshes and three small inner panel meshes). Overall, our study covered some of the most commonly used inner panel mesh sizes, ranging from 40 to 140 mm (stretched). We analysed the species composition and catch rates of the different inner/outer panel combinations with regression, multivariate analysis (cluster analysis and multidimensional scaling) and other 'community' techniques (number of species, dominance curves). All our analyses indicated that the outer panel mesh sizes used in the present study did not significantly affect the catch characteristics in terms of number of species, catch rates and species composition. Multivariate analyses and seasonal dominance plots indicated that in Basque, Algarve and Cyclades waters, where sampling covered wide depth ranges, both season and depth strongly affected catch species compositions. For the Gulf of Cadiz, where sampling was restricted to depths 10-30 m, season was the only factor affecting catch species composition and thus group formation. In contrast, the inner panel mesh size did not generally affect multidimensional group formation in all areas but affected the dominance of the species caught in the Algarve and the Gulf of Cadiz. Multivariate analyses also revealed 11 different metiers (i.e., season-depth-species-inner panel mesh size combinations) in the four areas. This clearly indicated the existence of trammel net 'hot spots', which represent essential habitats (e.g., spawning, nursery or wintering grounds) of the life history of the targeted and associated species. The number of specimens caught declined significantly with inner panel mesh size in all areas. We attributed this to the exponential decline in abundance with size, both within- and between-species. In contrast, the number of species caught in each area was not related to the inner mesh size. This was unexpected and might be a consequence of the wide size-selective range of trammel nets. (c) 2006 Elsevier B.V All rights reserved.

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O Grupo de Ajuda a Toxicodependentes (GATO) é uma instituição, sem fins lucrativos e de utilidade pública, que atua ao nível da prevenção, tratamento e (re)inserção de pessoas com problemas de consumo de drogas ilícitas, crianças e jovens em risco, população desfavorecida e inserida na medida de Rendimento Social de Inserção (RSI). No desenvolvimento da atividade do GATO são executadas campanhas de marketing de cariz social que, através da informação veiculada e meios utilizados, procuram sensibilizar a sua população-alvo, captar clientes, promover a sua aproximação à instituição e a apropriação de comportamentos preventivos, bem como difusão da imagem da instituição junto da restante comunidade. Neste pressuposto, o presente estudo permitirá, não só através de um inquérito por questionário aplicado à população-alvo constituída pelos clientes da Instituição GATO, como também de informação recolhida junto dos técnicos responsáveis, recolher dados que serão analisados mediante um esquema metodológico composto por duas etapas. Numa primeira fase aplicar-se-á uma Análise Não Linear de Correlações Canónicas (OVERALS) com o objetivo de detetar padrões entre os vários conjuntos de variáveis. Numa segunda etapa, com os resultados obtidos e com o recurso a uma Análise Não Hierárquica de Cluster, designadamente o procedimento Two-Step Clustering, será possível constituir grupos de indivíduos, os quais serão posteriormente validados mediante o Teste de Bonferroni de forma a constituírem-se Topologias e Tipologias de clientes que possibilitem orientações para o desenvolvimento de campanhas de marketing, consentâneas com o objeto social da organização.

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Dissertação de mestrado, Marketing, Faculdade de Economia, Universidade do Algarve, 2015