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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

On the dynamic management of marine resources

Dunn, Daniel Carl January 2014 (has links)
<p>Mismatches in the spatiotemporal variability of resource, resource users and management actions breeds inefficiency in the management of marine resources. To date, the spatiotemporal resolution and extent of fisheries management has been largely dictated by logistical and political constraints, and secondarily by the geographic range of the species or meta-population dynamics. Management units are rarely smaller than 1000 km2 in developed coastal fisheries, and management measures generally occur at resolutions larger than 100 km2. From a temporal perspective, the finest resolution of management measures is at best a month but more generally a year. As such, attempts to manage processes and patterns at sub-10 km, sub-1 month resolution often involve some level of spatiotemporal mismatch. To address the obvious spatiotemporal mismatch between a dynamic ocean and static management, to allow for a comprehensive implementation of ecosystem-based fisheries management, and to minimize inefficiency in our management of marine resources, we must seek to develop more dynamic management measures that allow managers to address scales, processes and patterns occurring under ten kilometers.</p><p>In this dissertation I apply point pattern processes, cumulative distribution functions, receiver operator characteristic curves, simulated annealing tools, regression models and clustering techniques to develop examples of two dynamic management measures and to compare the efficiency of static versus dynamic management measures. I show that autocorrelation analysis can inform the distances and times used in real-time closures based on move-on rules. Further, I identify optimum bottom temperature threshold values to separate individual species within the Northeast Multispecies Fishery from Atlantic cod. Results demonstrate that dynamic spatiotemporal management measures are widely applicable, and more effective and more efficient than static time-area closures. Unexpected trends in some results due to a changing climate indicate possible increasing thermal overlap between Atlantic cod and many other species in the fishery. Implications of scale in fisheries management and the importance of coarse scale (1 - 10km) ecological patterns to fisheries are discussed.</p> / Dissertation
2

An Ecosystem-Based Approach to Reef Fish Management in the Gulf of Mexico

Masi, Michelle D. 10 November 2016 (has links)
Fisheries managers have the potential to significantly improve reef fish management in the Gulf of Mexico through the use of ecosystem-based approaches to fisheries management. Ecosystem-based approaches are needed to address the effects of fishing on trophodynamic interactions, to better account for ecosystem-scale processes in model projections, and to recognize the short and long-term biomass tradeoffs associated with making regulatory choices. My research was concentrated around three objectives: (1) characterizing the trophodynamic interactions between Gulf of Mexico fishes, in order to construct an invaluable tool (a Gulf of Mexico Atlantis model) to be used in ecological hypothesis testing and policy performance evaluation for years to come; (2) predicting ecological indicators for the Gulf of Mexico that both respond to fishing pressure and are robust to observational error, and; (3) evaluating the performance of an ecosystem-based policy options for managing reef fish species in the Gulf of Mexico. To accomplish these objectives, a spatial, trophodynamic ecosystem model- Atlantis, was employed to represent the Gulf of Mexico marine ecosystem. To characterize trophic interactions between modeled species, I applied a maximum likelihood estimation procedure to produce Dirichlet probability distributions representing the likely contribution of prey species to predators’ diets. This provided mode values (the peak of the distribution) and associated error ranges, which describe the likely contribution of a prey item in a predator’s diet. The mode values were used to parameterize the availabilities (diet) matrix of the Gulf of Mexico Atlantis model. Investigating trophic interactions was useful for determining which species within the Atlantis model were data rich, and justified the emphasis on reef fish species and their prey items in subsequent analyses. Once parameterized and calibrated, I used the Atlantis model to project ecological indicators over a 50 year time horizon (2010-2060) under varying levels of fishing mortality. Principal component analysis was used to evaluate ecological indicator trajectories in multivariate space, to rank indicators according to how well they describe variability in ecosystem structure (termed ‘importance’), to reveal redundancies in the information conveyed, to quantify interannual noise and to determine how robust indicators are to observational error. Reef fish catch, Red snapper biomass, King mackerel biomass and Species richness indicators ranked the highest in terms of importance and robustness to error and in having low levels of interannual noise (i.e., requiring less frequent monitoring). I then used a management strategy evaluation (MSE) framework in Atlantis to evaluate some of these same indicators under an ecosystem-based approach to fisheries management – using robust harvest control rules to manage reef fishes. I found that this ecosystem-based policy option was able to maintain higher reef fish biomass, catch and ecosystem-wide biodiversity under any given level of fishing mortality when compared to a status quo management approach. These results suggest that harvesting under the HCRs encourages an alternative ecosystem state with a more Pareto-efficient tradeoff frontier than the status-quo policy. A potentially reduced extinction risk for reef fish is plausible under this ecosystem-based policy option. This research provides a quantitative look at the fishery performance and ecological tradeoffs associated with various policy options. MSE methodology using ecosystem-based policy performance metrics is also demonstrated. Tool development and findings from this research should aid in the development of ecosystem-based policies for this region.
3

O conhecimento ecológico local dos pescadores de Ubatuba, litoral norte do estado de São Paulo, como subsídio ao manejo pesqueiro com enfoque ecossistêmico / The local ecological knowledge of fishers from Ubatuba, São Paulo State northern coast (Brazil), as a contribution to ecosystem-based fisheries management

Marta Collier Ferreira Leite 06 July 2011 (has links)
Em Ubatuba (SP), a pesca apresenta grande importância sócio-econômica e requer, como em outros locais, um manejo adequado. Estudos sobre o conhecimento ecológico local dos pescadores (FEK) vêm sendo considerados promissores para o manejo pesqueiro, porém poucos são delineados especificamente com esse fim. Este estudo objetivou investigar o conhecimento ecológico dos pescadores locais visando fornecer indicadores detalhados sobre a ocorrência espacial e sazonal dos recursos e da pesca, além de propor uma nova metodologia. Para tal, a partir de uma adaptação do método Delphi, caracterizado pela busca de consenso, foram efetuadas 3 rodadas de entrevistas a um total de 109 pescadores locais, em 12 comunidades pesqueiras e 3 pontos de desembarques. O FEK revelou-se sólido e detalhado, visto que permitiu identificar informações relevantes para o manejo pesqueiro com enfoque ecossistêmico. Foi possível encontrar consenso em questões-chave, tais como: (1) a localização dos principais \"pesqueiros\" por arte de pesca, (2) a distribuição espacial e sazonal dos principais recursos, (3) a identificação potencial de habitats essenciais e (4) sugestões para o ordenamento pesqueiro. A metodologia proposta se mostrou de grande valia para a investigação do conhecimento dos pescadores e sua aplicação prática em questões de manejo. Espera-se contribuir para planos de manejo pesqueiro que considerem a \"saúde\" do ecossistema e as necessidades dos pescadores locais. / In Ubatuba (SP), fishing shows a great socio-economic importance, and, just like elsewhere, requires an effective management. Studies on fisher\'s ecological knowledge (FEK) have been considered a promissory field for fisheries management but few efforts have been specifically delineated with such a goal. This study aimed to investigate local FEK in order to provide detailed indicators about the spatial and seasonal occurrence of fishing and its fishery resources. It also proposes a new methodology, adapted from Delphi\'s which is characterized by the search of consensus. Overall, a total of 109 local fishers were interviewed along 12 local communities and 3 landing sites in 3 sequential rounds. FEK proved to be consistent and detailed, allowing to identify important information for ecosystem-based fisheries management and find consensus on key-issues such as: (1) the locations of major fishing grounds per the different fishing gears, (2) the spatial distribution and seasonal occurrence of major fishery resources, (3) identification of potential essential fish habitats (EFH), and (4) fishers\' suggestions for local fishery management. The new methodology proved to be useful for FEK studies and its practical application for management. Thus, it is expected to contribute in local fisheries management plans that consider both the health of the ecosystem and the needs of local fishers.
4

O conhecimento ecológico local dos pescadores de Ubatuba, litoral norte do estado de São Paulo, como subsídio ao manejo pesqueiro com enfoque ecossistêmico / The local ecological knowledge of fishers from Ubatuba, São Paulo State northern coast (Brazil), as a contribution to ecosystem-based fisheries management

Leite, Marta Collier Ferreira 06 July 2011 (has links)
Em Ubatuba (SP), a pesca apresenta grande importância sócio-econômica e requer, como em outros locais, um manejo adequado. Estudos sobre o conhecimento ecológico local dos pescadores (FEK) vêm sendo considerados promissores para o manejo pesqueiro, porém poucos são delineados especificamente com esse fim. Este estudo objetivou investigar o conhecimento ecológico dos pescadores locais visando fornecer indicadores detalhados sobre a ocorrência espacial e sazonal dos recursos e da pesca, além de propor uma nova metodologia. Para tal, a partir de uma adaptação do método Delphi, caracterizado pela busca de consenso, foram efetuadas 3 rodadas de entrevistas a um total de 109 pescadores locais, em 12 comunidades pesqueiras e 3 pontos de desembarques. O FEK revelou-se sólido e detalhado, visto que permitiu identificar informações relevantes para o manejo pesqueiro com enfoque ecossistêmico. Foi possível encontrar consenso em questões-chave, tais como: (1) a localização dos principais \"pesqueiros\" por arte de pesca, (2) a distribuição espacial e sazonal dos principais recursos, (3) a identificação potencial de habitats essenciais e (4) sugestões para o ordenamento pesqueiro. A metodologia proposta se mostrou de grande valia para a investigação do conhecimento dos pescadores e sua aplicação prática em questões de manejo. Espera-se contribuir para planos de manejo pesqueiro que considerem a \"saúde\" do ecossistema e as necessidades dos pescadores locais. / In Ubatuba (SP), fishing shows a great socio-economic importance, and, just like elsewhere, requires an effective management. Studies on fisher\'s ecological knowledge (FEK) have been considered a promissory field for fisheries management but few efforts have been specifically delineated with such a goal. This study aimed to investigate local FEK in order to provide detailed indicators about the spatial and seasonal occurrence of fishing and its fishery resources. It also proposes a new methodology, adapted from Delphi\'s which is characterized by the search of consensus. Overall, a total of 109 local fishers were interviewed along 12 local communities and 3 landing sites in 3 sequential rounds. FEK proved to be consistent and detailed, allowing to identify important information for ecosystem-based fisheries management and find consensus on key-issues such as: (1) the locations of major fishing grounds per the different fishing gears, (2) the spatial distribution and seasonal occurrence of major fishery resources, (3) identification of potential essential fish habitats (EFH), and (4) fishers\' suggestions for local fishery management. The new methodology proved to be useful for FEK studies and its practical application for management. Thus, it is expected to contribute in local fisheries management plans that consider both the health of the ecosystem and the needs of local fishers.

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