Rebuilding Strategies for Multispecies Fisheries: A Stylized Bioeconomic Model

In this paper, we investigate the bioeconomicimpacts of selected rebuilding strategies in amultispecies fishery. Using a stylizedbioeconomic model, we identify the conditionsunder which modifying the species selectivityproperties of the gear would contribute to therebuilding of over-exploited stocks. We examinethe cases where the stocks are biologicallyindependent and interdependent. Our analysissuggests that the success of the rebuildingprocess not only depends on the nature of thegear modifications but also on the biologicaland economic characteristics of the fishery. Copyright Kluwer Academic Publishers 2004bioeconomic modeling, catchability, multispecies, predator-prey, species selectivity,

Determinação da digestibilidade de nutrientes através da técnica do "saco de nylon" mais pepsina

Procurou-se verificar se a digestão de alimento em saco de "nylon", acrescida por tratamento com pepsina, seria equivalente à digestão obtida pelo método direto clássico, o de coleta total de fezes, já determinado anteriormente com ovinos. Seguiu-se um delineamento experimental em blocos ao acaso, com 6 repetições e 4 tratamentos, ou seja, tratamento A: ração contendo 100% de feno de capim de Rhodes; B: 85% de feno de Rhodes mais 15% de farelo de côco; C: 70% de feno de Rhodes mais 30% de farelo de côco; e D: 100% de farelo de côco. O animal fistulado utilizado para teste foi um bovino adulto, macho, de raça holandesa; o tempo de permanência do saco de "nylon" no rume foi de 72 horas; e a dieta consistiu em feno de Rhodes à vontade mais 2kg de farelo de coco por dia. Os resultados foram analisados através de análise da variância e curvas de regressão, e a comparação entre métodos de digestibilidade pelo teste de Tukey. Houve influência da associação de alimentos sobre a digestibilidade da fibra bruta (FB) e dos extrativos não nitrogenados (ENN), mas não sobre as demais frações - matéria seca (MS), extrato etéreo (EE) e proteína bruta (PB). A digestibilidade da fibra diminuiu com a inclusão e o acúmulo do nível de farelo na dieta. Não houve equivalência consistente entre os métodos testados de digestiblidade, variando ou não conforme o nutriente e o tratamento considerado. De modo geral, a inclusão de aproximadamente 15% de farelo de côco (tratamento B) favoreceu o melhor aproveitamento da dieta."Nylon bag" technique, followed by 48 hours of chloridric pepsin digestion, was tried for determination of the digestibility of proximate nutrients of Rhodes grass hay (Chloris gayana, Kunth, cv. callide) and coconut caque meal, and compared with results from "in vivo" method. In a randomized blocks design, 100% of Rhodes grass, and mixtures of 85% and 70% of the grass hay with 15%, and 30% of coconut cake, and 100% coconut cake, made up four treatments (A, B, C and D, respectively). The coefficients of digestibility for Dry Matter and for proximate nutrients in treatments A, B and C, determined through nylon bags in bovine rumen, were compared to the coefficients determined by total faces collection, in sheep. It was observed and concluded that: a) Position of samples along the supoort-bars inside rumen, as well as dfferent periods of animal usage, had no influence on the results; b) The calculated proportions of coconut in the mixture to obtain best digestibility were 17.48% for Dry Matter, 21.10% for Ether Extract, 29.01% for Crude Protein, and 16.49% for Non Nitrogenous Extrat. Crude Fiber digestibility decreased linearly as the coconut proportion in the mixture increased; c) "Nylon bag" and "in vivo" methods gave similar coefficients of digestibility for Crude Fiber for all treatments; for other nutrients, however, there were differences depending on treatments; d) TDN values for coconut cake meal, determined through "nylon bags" were 68.76% taking the average coefficients of digestibility from treatments B and C, and 68.08% from treatment D; "in vivo", the average from B and gave 71.06% of TDN; such a small difference in NDT suggests to have had no interference of foods on digestibility; e) NDT calculate for Rhodes grass hay was 58.38% "in nylon bags", and 44.81% "in vivo", when treatment A was the only one considered; thus, it could be concluded that nylon bag plus pepsin method did not work for Rhodes hay

Bacteriology of wild grey mullets, Mugil platanus Günther, from Cananéia, São Paulo State, Brazil

Bacterial strains isolated from the kidney and liver of grey mullets, Mugil platanus Giinther, 1880, captured in Cananéia, São Paulo State, Brazil, in October 1996, belong to the genera Micrococcus, Pseudomonas, Flavobacterium, Aeromonas and Vibrio. The resistance/susceptibility patterns of the isolated micro-organisms to nine antimicrobial substances were determined, the more resistant bacteria had been Pseudomonas, Flavobacterium and Micrococcus. To the best of the authors knowledge this is the first bacteriological study done on Mugil platanus in Brazil

Lotus international : rivista di architettura

It is a peculiar fact that while the natural environment is one of geography\u27s key research and teaching foci, it is difficult to specify what the discipline\u27s distinctive contributions to environmental understanding are. In part, this is because geographical research on the environment remains theoretically and empirically diverse, indeed fragmented. In turn, this is a function of the fact that the precision of this putative focus is deceptive since the term environment is enormously. On the one side, physical geographers study the environment in their own subdisciplinary languages. On the other side, human geographers apply the tools of everything from Marxism to post-structuralism to make sense of environmental discourses and transformations